Blood Flow Restriction Training
by Toni Lloret
© 2022 Toni Lloret Tercero
ISBN 9798411532005
No part of this work may be reproduced in any form or by any means whatsoever without the
express consent of the author
CONTENTS
.
INTRODUCTION
How I got started with BFR training
The history of elastic bands
My experience with BFR training
Disclaimer of liability
WHAT IS BFR TRAINING AND WHAT IS IT BASED ON?
What is BFR training based on?
The goal of restricting blood flow
Where was BFR first used and where has it been most scientifically proven?
Ischemia training
What material is used?
The vascular system
THE MECHANISMS OF HYPERTROPHY WITH BFR
How does blood flow restriction training work?
Increased lactic acid accumulation and metabolic stress
Myokines (Interleukin-6)
Hypoxia, Ischemia (Low Oxygen), and ROS
ROS (reactive oxygen species)
Increased activation of fast twitch fibers
Cellular Swelling
Hormonal Factors - Increases in Testosterone, GH and IGF-1
Growth Hormone Increases
IGF-1 Increases
Increases in IGF-1 after BFR training
Testosterone increases
Activation of mTORC1 and muscle protein synthesis
Myostatin reductions
Muscle damage with BFRT
SPECIFIC ADAPTATIONS OF BFR TRAINING
Local mechanisms (at the cellular level) of BFR Training
Muscular and cardiovascular adaptations
Hypertrophy of type I fibers
The crossover effect with BFR
Musculature effects without BFR
THE SECURITY OF BFR TRAINING
Data and studies on the security of BFRT
Research and studies on BFRT security
Cardiovascular safety, muscle damage and oxidative stress
Cardiovascular risk in population with risk factors
RISKS AND CONTRAINDICATIONS OF TRAINING WITH BFR
How do you know the risk of BFR training?
Variables that must be monitored to minimize the risks
How to assess the risks of BFR training
BFR training for people suffering from any type of pathology
The ankle-brachial index
DEVICES FOR BFR TRAINING
Compression bandages
Inflatable compression cuffs (Kaatsu)
Medical tourniquets
Occlusion bands with adjustable strap
PRESSURE LEVEL AND HOW TO CALCULATE IT
How to measure BFR band pressure subjectively
Capillary refill time
TYPES OF BFR TRAINING
Blood Flow Restriction in the absence of exercise
Blood Flow Restriction with aerobic exercise
Blood Flow Restriction in strength training
Maximum recommended time with BFR
Intermittent BFR Training
Recommended pressure with BFR
Sets and repetitions approach
Training with BFR and loads over 40% of 1RM
Systemic effect with BFR training
Strength training with BFR in elite athletes
BFR TRAINING GUIDE FOR HYPERTROPHY AND STRENGTH
How to place the occlusion bands
On the arms
On the legs
Forearms and calves
Place bands on the calves?
Pressure of occlusion bands
Different types of exercises
Multi-joint exercises
Isolation exercises
BFRT loads
Table of 1RM percentages and number of repetitions
Training volume
Training frequency
BFR Intermittent YES or NO
Sets and repetitions
Starting with training and adjusting pressure
Initial feelings with BFR training
Mind-muscle connection
Exercises, sets, and repetitions with BFR
Biceps
Triceps
Forearms
Quadriceps
Hamstrings
Calves
BFR training on muscles not receiving BFR
SUPPLEMENTATION AND TRAINING WITH BFR
Recommended or useful supplementation with BFR training
Creatine Monohydrate
Instructions for use and creatine dosage
Beta Alanine
Instructions for use and beta alanine dosage
Betaine
Instructions for use and betaine dosage
Electrolytes
Instructions for use of electrolytes
L-CARNITINE AND BFR TRAINING
Why does BFR training promote hypoxia?
Neuromuscular fatigue and hypoxia
Acetylcholine, neuromuscular fatigue, and L-carnitine
Benefits of L-carnitine on hypoxic stress
The role of serum L-carnitine in biological functions
Instructions for use and L-carnitine dosage
CONCLUSIONS
BFR training and advanced protocols
Final recommendations
About the author
SPORTING AWARDS
REFERENCES
INTRODUCTION
My goal with this book is to provide you with an in-depth understanding of blood flow restriction
training. We will look at the different mechanisms and adaptations that are generated with BFR
training, and in case you decide to incorporate BFR into your training, do it safely.
The first thing I would like to make clear is that blood flow restriction training is not a fad, nor is it
intended to be. Although some may label it as a fad without even the slightest idea of the various
physiological responses that occur when we apply blood flow restriction during strength training.
Fortunately for those of us who seek to learn and improve, there are a large number of
researchers conducting studies on training with blood flow restriction, and the scientific community is
increasingly interested in this type of training, as there are many benefits and discovering all the
mechanisms and processes by which the various adaptations occur is a challenge for researchers.
The fact is that, without pretending to be a fad, more and more athletes from all types of
disciplines are adding blood flow restriction training to their routines or training plans. This is not a fad,
but rather the result of a rational and intelligent decision. Especially when blood flow restriction training
(BFRT) is well understood and applied correctly.
There are many benefits that can be obtained with BFR training which we will see throughout the
book, as well as understanding some of the physiological processes by which these benefits occur
and reviewing the scientific evidence available to us.
Getting back to the topic of fads... I have always been quite skeptical of fads, they tend to be
cyclical and always repeat themselves, they come, they go, and then they come back again and
again. Fads in fitness usually come in the form of new supplements, new training systems, or new
diets.
Fitness is like that, it goes by fads that repeat cyclically, but rarely is there anything new. And of
course, one system is not going to be better than another just because it's new. Nor is there one way
of doing things that is consistently better than another for everyone. A training system works when it
meets the basic principles of training and when it is applied at the right time and in the right way.
It must be understood that if something works, it is simply because it complies with physiological
and training principles, and that is why it works, not because it is a training or a diet with special or
magical powers.
What usually works best, and rarely fails, is hard work done right. But hard work is something that
many people do not like, so it is very easy to fall into the hands of sell-outs who promise you that by
doing half as much you will get twice as much. The speech that with little effort you will get great
results is something that everyone likes and a pleasant lie is easy to believe, that is one of the
reasons why many people often fall into deception.
Very promising methods or systems are almost always a hoax, or they don't really work as well as
promised.
That's exactly what I thought every time I heard about the benefits of BFRT, too good to be true.
That's why, despite having long been aware of how it works and the theory behind it, I hadn't really
explored it and studied it in the depth it deserved. Partly because I don't like the salesmen, and partly
because I know that hard work is irreplaceable, and that to get a good result and excel in whatever
you propose you will always have to work really hard.
How I got started with BFR training
In March 2019 came the confinement in Spain, and having to train at home with just some elastic
bands to keep 120Kg quite lean was presented as a good challenge. As I like challenges, I took on
this one and started training with just some elastic bands, which was the only material I had and that I
bought the same day they announced the confinement. It was also at that time that along with the
elastic bands I also started to use occlusion bands. But this time I began to use them much more
regularly in all workouts, and not on an occasional or sporadic basis as I had done some time before.
To my surprise, not only did I manage to maintain all my muscle mass but in fact some groups
such as the arms were improving.
At that time in social networks began to generate a debate in which some bodybuilders argued
that with elastic bands you could not achieve gains in muscle mass and that at most, you could
maintain the muscle mass you already had. Evidently, and as happens all too often, the evidence
supporting the hypothesis that elastic bands could not increase muscle mass was backed up by
several "because I said so" university studies.
According to all the "because I said so" university studies, with elastic bands you could maintain
muscle mass, but not gain muscle mass. Already from the beginning, this does not make sense,
because as soon as we understand how hypertrophy works, we know that the most important thing to
maintain or gain muscle mass is the mechanical tension and this is not determined by the external
load, but by the tension generated by the fibers themselves when they contract slowly.
We know that a high degree of mechanical tension can be generated even when using low loads
as long as the sets is taken to muscle failure. Those last repetitions in which the speed decreases a
lot are the ones that produce more mechanical tension in the fibers and these do not know if there are
100Kg or 50Kg in the bar or if the resistance they have to overcome comes from a bar, dumbbells, a
machine or elastic bands, the fibers only understand the tension they have to produce to generate
force.
To say that with elastic bands you can at most maintain muscle mass is totally absurd. Since, if
with a workout of say X sets you manage to maintain muscle mass, if you add more work (say 2X),
you multiply by 2 the stimulus and also the mechanical tension and you could therefore increase
muscle mass. In fact, in conventional hypertrophy training the only difference between what might be
just maintaining muscle mass and gaining muscle mass can be determined by the training volume
variable. So, if with elastic bands you could only maintain, if you wanted to improve you would simply
have to add more volume.
In any case, we also have evidence that with simple elastic bands you can increase hypertrophy,
there are even some studies in which with bands there is more activation than with machines or
gravitational loads.
It is obvious that the more material you have the better you will work, and that using only elastic
bands I do not think it is optimal, since, among other things, it is more difficult to measure a
progression of loads. But that does not mean that with some bands you can generate a large amount
of mechanical tension in the fiber and thus generate adaptations of hypertrophy and strength, this has
been demonstrated on many occasions and there are several investigations in this regard.
I knew that with elastic bands it was possible to gain muscle mass because I was seeing it in
myself, as well as in many of the people I advise. Practically all those who were not discouraged by
the closing of the gyms and continued training at home with just a few bands continued to progress to
a greater or lesser extent and obviously according to their degree of involvement and commitment to
their diet and training program.
In any case, I must admit that I found the subject of elastic bands an interesting topic, so I
investigated more about it, and I was surprised by the amount of literature there was about it, so I
ended up reading a lot of publications and practically all of them came to the conclusion that with
elastic bands you could gain muscle mass perfectly, there were even studies in which the subjects
achieved better results with elastic bands than with gravitational loads.
In order not to bore us with studies on elastic bands, since talking about resistance bands or
elastic bands is not the objective of this book, I will simply cite two meta-analyses that compile all the
studies that directly compare elastic bands against gravitational loads or machines, and in both metaanalyses they reach the same conclusion.
The conclusion is that the same level of muscle activation and the same gains in strength and
hypertrophy can be obtained with both elastic bands and gravitational loads (Lopes et al. 2019)
(Aboodarda, Page, and Behm 2016) [1][2].
The argument of the detractors of elastic bands was that such studies are done in a normal
population and not in bodybuilders. That was true, the subjects of these studies were not
bodybuilders, but there were people who trained with loads and for much more objective questions
such as measuring the level of muscle activation is indifferent whether you are a trained person or not.
In any case, the fact that there was no evidence in the bodybuilder population should not
necessarily be a problem. Bodybuilders are not made of different material, they are governed by the
same physiological principles as any other person.
On the other hand, it is known that if the sets are taken to failure or very close to muscle failure, it
will generate enough mechanical tension to generate hypertrophy adaptations even with light loads.
So, if with elastic bands subjects who trained regularly could obtain gains in hypertrophy and strength
a bodybuilder could also.
But in my case with 120 kilos and a great amount of those kilos were of lean meat I thought that
perhaps I would need something more to obtain gains in strength and hypertrophy, so I thought that
using blood flow occlusion bands to train with blood flow restriction could help me to optimize the
resources I had at that moment, which I already said was only a set of elastic bands.
The history of elastic bands
You may be wondering why I have told you the story of the elastic bands and the debate that
arose around it. Well, I just thought it was relevant because with occlusion bands and blood flow
restriction training the exact same thing is going to happen (or is already happening). There are going
to be many opinions against BFRT but they are really based on "because I said so" university studies.
To give you an example, some of the reasoning that some people give against BFRT is along the
lines of "if it's so good how come so few people do it? if it's so good why don't the pro bodybuilders do
it?
As you can see, these are very logical and convincing reasonings, very typical of "because I said
so" university students and researchers. After reading this book when you hear them you will know
that really what is behind that kind of arguments is a lot of ignorance about the subject in question.
In part, this ignorance is completely normal since there was not yet a book that goes into the
depths of BFR training and unravels the processes by which adaptations of hypertrophy, strength, and
other positive adaptations are obtained.
In order to fill that gap I have written this book, here we will see absolutely everything about BFR
training and for this we will review the most current scientific evidence, nothing to say "it does not work
because if it were good the pros would use it", "yes it works because it works for me", or other
arguments based on university studies of "because I say so".
In the book we will review all the evidence we have today on BFR training, and we will also try to
understand the physiological processes and adaptations that occur with BFRT. Once you have all the
data and knowledge you will be able to draw your own conclusions.
In fact, I am sure that after reading the book you will understand why I use BFR in all my training,
and the people who have taken my BFR Training Expert course are also applying BFR in their
training.
If more and more people are using BFR to improve in all kinds of sports it is not because it is a
fad, it is because it helps them to get better results and this is documented in many of the studies that
we will see throughout the book.
My experience with BFR training
Using occlusion bands and training with blood flow restriction was something I had done in the
past and did from time to time in some mesocycles. It was something that always gave me a good
feeling, but I never considered the idea of applying BFR continuously. Basically, because the evidence
indicated that with only a few weeks you get improvements, and most of the recommendations given
in the literature are usually to use them for a few weeks.
Basically, it is recommended to use BFR for only a few weeks because there are no studies yet
where blood flow restriction training is used in the medium or long term. Most studies are used for 3 or
4 weeks and there are very few studies of 8 weeks or more.
About BFR training, I had read quite a lot of research clearly demonstrating that with BFR training
you can gain muscle mass even with light loads.
So, during quarantine and seeing that I only had some elastic bands at my disposal, it seemed
like a good time to apply BFR training in a more serious and, above all, constant way. So, I set out to
see for myself how BFR training could work for a 120kg bodybuilder.
I was confident of getting good results since on the one hand I had reviewed many studies where
they concluded that with elastic bands you could gain strength and hypertrophy, and on the other hand
I had seen a lot of evidence of how training with blood flow restriction improved adaptations in
hypertrophy and strength.
Among the studies I reviewed was an intervention by Tomohiro Yasuda and colleagues [3], where
they found that training with elastic bands and blood flow restriction improved hypertrophy and
strength without altering arterial stiffness. Yasuda's study was on a population between 61 and 85
years old, but that is precisely what made it even more interesting.
The usual thought of a bodybuilder when faced with that type of trial is the following: "that study is
useless because the fact that some grandparents gain hypertrophy and strength with elastic bands
and training with BFR cannot be extrapolated to a bodybuilder who can gain hypertrophy and strength
training with elastic bands and BFR".
However, my thinking was more like this; if older adults who probably don't know how to train as
well as they could and with all the drawbacks that advanced age presents for gaining strength and
muscle mass have managed to improve strength and hypertrophy with a simple training program
using only elastic bands and training with blood flow restriction, I will be able to achieve much more by
training like a bodybuilder and using elastic bands and BFRT.
So, I went for it and did all kinds of testing and all kinds of training with the elastic bands. I started
with the protocols that the evidence and the top researchers in the field suggest and then applied my
own protocols.
The protocols suggested by different researchers such as Cortobius and Westblad, 2016,
Patterson et al., 2019, or Hanke et al., 2020 [4][5][6] will be discussed below.
The most advisable to start training with BFR, will be to start with the protocols recommended by
the researchers. But keep in mind that this type of protocols is not designed for advanced
bodybuilders, so after an initial period of adaptation they can be quite short if we already have a
certain level and the goal is to obtain maximum gains in strength and hypertrophy.
So, in case you are an advanced bodybuilder these protocols can and should be improved by
progressively increasing the difficulty in case you want to keep improving session after session. That
is why, when you are perfectly adapted to BFR training you can extend the time of the sessions and
apply intensity techniques such as micropauses or drop sets with BFR. But keep in mind that there are
still no studies on BFR training and advanced intensity techniques, only empirical evidence from all of
us who are in the BFR training course and have been training with this type of training for some time,
and that once adapted to the BFRT we use it with advanced training techniques and get good results.
In the telegram group whose link I posted a few paragraphs back there are a lot of positive
testimonials using the BFRT with advanced techniques or loads of well over 50% of the 1RM. But as I
explain in the BFRT Expert course, it is necessary a previous adaptation and to be for quite a few
weeks using traditional BFRT protocols before moving on to more demanding workouts.
So that everything goes well and there is no problem and regardless of the level you have and the
years you have been training (in BFRT you are a beginner), you should always start with the simplest
protocols that we will see in the book and once they are perfectly controlled you can begin to increase
the difficulty of the workouts.
It is very important that in the case of increasing the difficulty and intensity of training with BFR is
done in a very progressive way to obtain adaptations without generating problems such as
rhabdomyolysis and other problems that could occur in the case of overdoing the training, all this will
talk in depth in the chapter focused on the risks and as always all based on the evidence available to
us. This chapter is a must read before starting to train with BFR.
In my case, I also started with the protocols proposed in the literature, but after a few weeks I
realized that for someone of my level and size perhaps they were insufficient, or at least I could add
more difficulty to them so that the training would challenge me more so that it would be necessary to
generate adaptations and improve to be able to face more and more intense stimuli.
So, although I had noticed improvements with the recommended protocols, I thought it was time
to start making my own protocols much more demanding, so I started using the occlusion bands in a
way that was far from the recommendations of the researchers in terms of time of use, weekly
sessions, load or percentage of 1RM used, duration of rests, or number of sets and repetitions.
Experimenting with different protocols I found a large number of combinations that I could make,
increase the pressure at certain times, decrease it in certain exercises and loads used, increase the
time of the sessions with BFR, or even directly use the BFR in the entire training session, change the
type of sets and use advanced techniques, reduce the ranges of repetitions, increase the percentages
of 1RM, etc. In short, I did things very different from those recommended in the literature to increase
the difficulty of the exercises and continue to force positive adaptations.
After experimenting for several months applying BFR training to all my workouts (not only when
training legs or arms), the results I got with just elastic bands and occlusion bands seemed so good,
that the occlusion bands and BFR training became part of all my workouts, and since then I have not
stopped using BFR in my workouts. In my case, I work with BFR any muscle group, not only the
extremities, but I also use BFR to improve groups to which BFR is not directly applied. In the book we
will see the evidence and the processes by which improvements in strength and hypertrophy are
obtained even in groups in which we do not restrict blood flow directly, such as the back, shoulders or
chest.
I have been using BFR training continuously for over two years and have tried and continue to try
several different ways of training with BFR, applying advanced training techniques and different
combinations of sets and repetitions.
In this book we will see all the scientific evidence behind training with blood flow restriction, thus
trying to understand the physiological mechanisms that make training with blood flow restriction
(BFRT), achieve increases in strength and hypertrophy with loads of 20-50% of 1RM similar or higher
than when using loads of 70% of 1 RM or more.
In the practical part we will see the best way to start with BFRT according to the researchers. We
will also look at some of the physiological principles by which adaptations occur with blood flow
restriction training and all the hypotheses that researchers are considering determining the processes
and pathways by which blood flow restriction training produces specific adaptations at various levels,
not only in increasing muscle mass and strength but also at the cardiovascular level.
My goal with this book is for you to learn in a simple way what I have learned in several years.
Once you have that knowledge it is up to you to use (or not) blood flow restriction training and get
better results with your work.
I sincerely hope and believe that after reading the book and starting to apply BFR, there is going
to be a before and after in the way you train and the results you are going to get.
Let's go there!!
Disclaimer of liability
In no case do the proposed exercises or the advice and conclusions that can be drawn from this
book imply advice on health issues.
In this book I simply relate my experience with BFR training and share some of the knowledge
acquired based mainly on the evidence available today on BFR training. In no case am I responsible
for the use or misuse of the information I share in this book.
In the event that you wish to implement any of the exercises or techniques described in this book,
you do so at your own risk, and before starting an BFR exercise program, you should check with your
physician to make sure that you are fit for exercise. A doctor will ultimately be the one to give the goahead and decide whether you can assume the risks associated with the execution of this type of
training.
WHAT IS BFR TRAINING AND WHAT IS IT BASED ON?
Blood flow restriction training (BFRT) is known by several names, such as occlusive training,
occlusion training, ischemic training, or local ischemia training [7]. However, although it has several
names, some of them that are often used are not correct.
It would not be correct, for example, to refer to BFR training as blood flow occlusion training or
occlusive training. In any case, we can speak of training with blood flow restriction since the aim is to
restrict part of the venous return and not to occlude the blood flow.
A restriction refers to a decrease in blood flow, while an occlusion refers to a complete closure,
and it is not an occlusion that we are looking for when we apply bands or any other device to restrict
blood flow. The bands can be called occlusion bands because they can serve perfectly well to occlude
the blood flow, that is, to completely cut off the flow, but we are going to use them to restrict the blood
flow, which as I mentioned before is not the same as occluding, so we could also refer to them as
blood flow restriction bands.
In any case, it is important to know that the original name of this system or training method is
Kaatsu. The method was born in Japan many years ago, specifically in 1983, although the date of
creation may vary depending on the sources consulted, but there is no doubt that its creator was
Yoshiaki Sato [8].
Dr. Yoshiaki called it the Kaatsu method, which means method with additional pressure and
comes from KA (additional) and ATSU (pressure).
The original Kaatsu method consists of training with light loads between 20 and 40% of 1RM, but
performing the exercises with blood flow restriction in the involved extremities. Initially this training
method was created to improve the mobility and autonomy of the Japanese elderly.
If we do a search in pubmed on BFR training, the first scientific research that appears is from
1976, but it has nothing to do with the BFRT, it is a study in trained and sick dogs to which the flow of
a coronary artery is restricted to one of the groups and that is why it appears in the searches. But in
reality, it was not until the 1990s that serious trials based on this training method began to be
published more regularly.
We could say that from 2010 researchers began to be much more interested in BFR training both
to improve hypertrophy and strength and to improve adaptations to improve aerobic performance, and
it was precisely from 2010 when there began to be many more publications on training with blood flow
restriction.
Since then, the interest in this type of training has not stopped growing exponentially, and
publications have increased dramatically as can be seen in the following graph where we can see that
in 2020 there are 172 publications related to blood flow restriction training. In the last 3 years alone
there are more publications than in the last 30 years, and there are more and more since the interest
of researchers in the adaptations that occur with BFR training is increasing.
Thanks to the amount of new research that emerges practically every week, a great deal of
progress is being made in this field, and the discoveries, results, and conclusions that researchers are
drawing about BFRT make it exciting to investigate its possible applications, which are many and
varied.
Research on the BFRT has not stopped advancing and every day new research appears, and
more details are known about the different ways in which the BFRT helps in such disparate things as
recovery from injuries, type II diabetes, increased adaptations in aerobic endurance sports, or
increased hypertrophy and strength.
What is BFR training based on?
In a very summarized way, we could say that the Kaatsu method or BFR training is about
restricting blood flow during exercise with submaximal loads, i.e., with loads ranging from 20% to 50%
of 1RM, with the aim of stimulating hypertrophy.
Although when the objective of BFR training is to achieve adaptations and improvements in
aerobic endurance sports the protocols are different, later we will see different types of protocols, but
in this book, we will focus on the optimal protocols to achieve hypertrophy and strength gains.
The methodology used to restrict blood flow is to apply a device to restrict blood flow. This device
can be an inflatable cuff, elastic bands, a medical tourniquet, or any other type of device that can be
used to restrict blood flow to an extremity during exercise.
As a general rule (although there are exceptions), the intensities used in the scientific literature
and in practice are between 20% and 50% of 1RM. These are always submaximal intensities.
It is important to note that at least initially and in order to pre-serve safety, BFR should only be
performed during exercise with submaximal loads that can range from 20% to 50% of 1RM.
Later, we will see some advanced protocols, where the loads to be used need not always be 50%
of 1RM or less. But for the moment, and until we get into the dangers, contraindications, and correct
practice in the use of blood flow restriction training, we will stick to the general recommendations.
In any case, and as a general rule, BFRT should never be performed at maximum intensities of
85% of 1RM or more. Since precisely the great advantage of BFRT is to achieve the benefits that
would be obtained by training with high loads but using much lighter loads. Furthermore, using loads
of more than 70% of 1RM incorrectly could lead to problems, although this can be qualified since
aspects such as the pressure of the bands, the time of use, or the adaptation of the athlete to training
with BFR with loads higher than 50% of 1RM are also factors that must be considered and that could
allow a given athlete to use loads of 70% or even more without problems.
That's why yes, you could increase the load a little more to about 70%, in fact, many of my
workouts I use loads of 70% of 1RM or more in depending on which exercises. But for most users it
would not be the most advisable to apply the BFR with loads of 70%, especially if there has not been
a previous adaptive period. And if for any reason, without being fully adapted or during the adaptation
period, you want to start using loads higher than 50% of 1RM, it would be highly recommended to
reduce the pressure that the occlusion bands exert so that the restriction is less as higher loads are
used.
This point will be discussed later as it is an advanced issue of the BFRT, but it offers many
interesting possibilities to achieve not only metabolic adaptations at a local level, but also strength
adaptations at a neural and structural level, such as improvements in tendon stiffness that occur when
high loads are used.
Although it is true that improvements in tendon stiffness do not occur with light loads, things
change when BFR is used, so that with BFR the adaptations in tendon stiffness that occur when we
use maximum loads without BFR do occur.
On this point we have the trial by Centner et al. 2019 [9], in which it was seen that the adaptations
that occurred in the Achilles tendon after training with light loads and BFR were comparable to those
that could be obtained with loads closer to the 1RM.
Almost certainly these positive adaptations in tendon stiffness are related to the much higher
growth hormone spikes that occur with BFR training. These peaks can be as much as 10 times higher
than when BFR is not used.
That growth hormone releases are higher with BFR has been seen in several trials such as
(Gordon et al. 1994) (Gotshalk et al. 1997) (Ahtiainen et al. 2004) (Pierce et al. 2006) (Takano et al.
2005) (Takarada, Nakamura, et al. 2000) [10][11][12][13][14][15] more on this later.
The goal of restricting blood flow
The objective of restricting blood flow is to create an imbalance in the homeostasis of the
contracting muscle.
This imbalance stimulates peripheral (local) and systemic anabolic mechanisms that affect the
entire body and subsequently some of these mechanisms lead to anabolism through various
pathways. Ultimately, the goal we seek and what we achieve with strength training and BFR are
hypertrophy and strength adaptations.
Since the exercises that are usually used for BFRT are exercises that generally use low loads and
do not require a too complex technique, the fatigue at the structural level (tendon and joint) that occurs
is quite low and recovery is usually fast as long as the BFRT system is used correctly.
Where was BFR first used and where has it been most
scientifically proven?
Blood flow restriction has been used primarily for injury rehabilitation, immobilization, and certain
types of injuries where excellent results have been seen.
BFR training is also applied in strength and aerobic endurance training, or even during activities
such as walking, as well as in people (whether elderly or not), who are not able to perform exercises
with loads above 50% of 1RM for whatever reason.
In its beginnings, BFRT was applied mainly for the rehabilitation of injuries and the maintenance
of muscle mass in bedridden or elderly people. This was probably one of the reasons why it did not
lose the interest of many athletes, since BFR training is associated with injury rehabilitation or the
exclusive use of very light loads.
The truth is that currently much of the research is focused more on its applications to both
strength and aerobic endurance training. BFRT research is being applied in both sedentary people
and advanced athletes, obtaining incredible results in both sedentary and elite athletes. Throughout
the book we will see several studies in this regard.
Ischemia training
One thing to keep in mind about BFR training is that BFR training shouldn't be confused with
ischemia training (Sundberg CJ. 1994)[16].
It should be clear that with blood flow restriction training we don't seek in any case to occlude the
arteries, so that it doesn't induce total ischemia within the skeletal muscle.
Ischemia is the arrest or reduction of blood flow through the arteries in each area, which implies
elevated risks. The objective of applying blood flow restriction should never be to occlude the arteries,
but rather to promote a state of accumulation of blood in the capillaries within the musculature of the
extremities. Therefore, the pressure of the occlusion bands should never be excessive, and we'll see
in detail later how to control the appropriate pressure.
What material is used?
In blood flow restriction training (hereafter BFRT or BFR training), in order to restrict blood flow,
an elastic band, an adjustable strap, an inflatable tourniquet, or any other device that can partially
restrict blood flow to the limb of interest can be used.
Later on, we'll see what kind of devices are used, the pros and cons of each of them, as well as
what kind of device I recommend and why. And also, obviously we'll see the correct way to apply the
blood flow restriction depending on the type of training or sets we're going to perform.
The vascular system
To understand in a very summarized way how the BFRT works, we've to see, even in a very
summarized way, how the vascular system works.
Very briefly, the vascular system or circulatory system is composed of veins and arteries. The
arteries are the ones that take the blood from the heart and distribute it to the rest of the body, and the
deoxygenated blood returns to the heart through the veins, this blood flow that goes through the veins
back to the heart is what's known as the venous return.
One thing to keep in mind is that the arteries are found and distributed in the deeper parts of the
extremities (arms and legs), while the veins are kept closer to the surface of the skin and are therefore
more visible.
This means that, if we apply the right amount of pressure in the right place with a tape or device
that acts as a tourniquet, we can restrict the blood flow of the veins in the limb where we apply the
device, thus preventing a large part of the blood from flowing out of the limb, but at the same time
allowing the entry of oxygenated blood that travels through the arteries, so that there will be more and
more blood in the muscle.
By restricting venous return, more blood and waste metabolites accumulate in the muscle we're
training, which will trigger a set of multiples signaling cascades and hormonal responses that provoke
an anabolic reaction in the slow, but also fast muscle fibers.
And it’s in response to all these anabolic processes that improvements in hypertrophy are
achieved even with relatively light loads.
This has many advantages, since apart from obtaining a better anabolic signaling due to various
biochemical processes that we will see later, training with lighter loads avoids much damage and
fatigue in structures and tissues such as joints or tendons. Muscle damage is also reduced, thus
reducing recovery time, and a sets of multiple advantages are also obtained, which we will see in
detail later on.
THE MECHANISMS OF HYPERTROPHY WITH BFR
How does blood flow restriction training work?
Training with blood flow restriction promotes muscle growth through different pathways.
In this chapter we will review some of the mechanisms that have been observed in scientific
research on the different pathways and mechanisms that cause a hypertrophic response to occur with
blood flow restriction training.
Normally when the training system with loads is the traditional one, to achieve hypertrophy what's
suggested is that hypertrophy gains are going to be generated in an optimal way when loads ranging
from 65% to 85% of a maximum repetition (of 1RM) are used.
This means that someone who can bench press 100Kg and perform a single repetition with
100Kg if he aims to gain muscle mass should train with loads ranging from 65Kg to 85Kg to generate
hypertrophy adaptations. In other words, you should use loads between 65% and 85% of your 1RM.
However, when using blood flow restriction training, studies show that by training with blood flow
restriction with loads of 20-40% of 1RM you can obtain the same muscle mass gains as when training
with the traditional system and with loads ranging from 65% to 85% of 1RM or more.
There are many, many interventions that show how training with blood flow restriction can achieve
similar or even greater increases in muscle mass even when using much lighter loads.
In a study by Takarada et al. in 2000 [17], the research focused on the muscles of the arms
(biceps, biceps brachii and triceps), and it was observed that the group training with blood flow
restriction showed greater increases in biceps cross-section.
At this time, there is already a large amount of evidence with similar results in favor of BFR,
studies that have been done in different population groups, and in different muscle groups. And in
these studies, it has been proven that thanks to BFR training, gains in both hypertrophy and strength
are obtained even with loads ranging from 20% to 40% of 1RM.
As a sample of some studies in which with the BFRT and low loads similar or superior results to
conventional hypertrophy training are achieved we've the interventions of Abe et al., 2004, Abe et al.,
2010, Possomato-Vieira, José S. and Khalil, 2016, Drummond et al., 2008, Evans, Vance and Brown,
2010, Patterson and Ferguson, 2010, Takarada, Takazawa, et al., 2000, Yasuda et al., 2010, Yasuda
et al., 2015, Wilson et al., 2013 or Madarame et al., 2008) [18][19][20][21][22][23][17][24][25][26][27].
Increased lactic acid accumulation and metabolic stress
Applying a band to restrict blood flow enhances the production of metabolic by-products within the
muscle, such as lactic acid, hydrogen ions, reactive oxygen species and other waste metabolites.
These metabolic by-products are chemical irritants to the muscle and represent a normal
physiological response that occurs during loaded training.
The metabolic by-products cause some stress to the muscle tissue and all surrounding tissues,
and by being trapped within the muscle and not allowing them to dissipate, further muscle growth is
stimulated.
Muscle tissue tries to respond to these stressors by adapting, and to this end, enhanced signaling
of muscle protein synthesis is generated, which favors the process for the formation of new muscle
proteins (myosin, actin, as well as tropomyosin, troponin, titin, haze, α-actin and myomesin). In
addition, increased muscle glycogen storage capacity is generated.
The accumulation of lactic acid and other waste metabolites is one of the mechanisms that
contribute to muscle growth when we perform BFR training. This has been proven in numerous
studies that confirm a substantial increase in lactate levels, some of which I'll mention later.
The formation and accumulation of lactic acid within the muscles is the result of "anaerobic"
metabolism and occurs primarily when the muscles have to apply force in an oxygen-deprived
environment.
Under conditions of abundant oxygenation, muscles work using the Krebs cycle, or citric acid
cycle, and thus produce the energy necessary to apply force during a workout.
However, once oxygen is depleted, muscles switch to an energy-producing mechanism called the
Cori cycle, also known as the lactic acid cycle.
The Cori cycle or lactic acid cycle basically consists of taking lactate to the liver where it’s
converted back into glucose through gluconeogenesis, returning to the circulation to be taken back to
the muscle and used as energy. Gluconeogenesis is a metabolic pathway that allows the biosynthesis
of glucose to be used as energy from non-glucose precursors, in this case from lactate.
Blood flow restricted training with light loads increases lactate considerably with respect to
training at intensities of 65% of 1 RM or higher [16][28][29][30][31][32][33].
During BFR training, an increased accumulation of metabolites has been observed [34],
therefore, it’s thought that part of the hypertrophy gains achieved with BFR training may be due in part
to this increased metabolic stress.
Very relevant evidence that could confirm that indeed metabolic stress must necessarily be
involved in fiber growth can already be seen in the 2009 study by Abe et al [35].
In the study by Abe et al. a group of men managed to increase the muscle mass of the lower
extremities after only three weeks of walking with occlusion bands on their legs.
Obviously, under normal circumstances without BFR, no young, healthy subject is going to gain
muscle mass simply by walking or performing low-intensity aerobic exercise, so this study by Abe et al
[35] provides strong evidence that factors other than mechanical stress was responsible for the
improvements in hypertrophy.
Mechanical stress may not have been involved since simply walking can't generate enough
mechanical stress on the fibers to generate hypertrophy adaptations, so everything points to the fact
that when BFR training is used, although mechanical stress is the main mechanism to generate
hypertrophy, it may not be the only factor, it’s very likely that there are other mechanisms involved
besides mechanical stress by which hypertrophy gains can be achieved with BFR training.
A year later Takashi Abe and colleagues [18] replicated the study again to see if similar results
were obtained with older men and indeed they did, they again experienced hypertrophy gains from
simply walking with BFR bands. That older people who've more difficulty in gaining muscle mass also
obtained improvements, seems to me to be a very interesting detail.
The results of these studies suggest that the metabolic stress generated during low-intensity
aerobic exercise may be a key mediator of muscle growth.
In fact, the researchers found that significant increases in muscle cross-sectional area correlated
significantly with changes in inorganic phosphate (r=.876) and intramuscular pH (r=.601) during
occlusion.
Kaatsu Walking, as walking with BFR bands on the thighs is called, was first investigated by
Takashi and colleagues in 2006 [36], and as early as 2006, increases in muscle size could be
demonstrated when walking with blood flow restriction bands.
What must be considered is that the subjects in Takashi Abe's studies were untrained people.
Someone with a certain level would expect to obtain hypertrophy gains in the lower extremities by
simply walking with occlusion bands, but perhaps muscle mass could be maintained in case of injury
or inability to train the lower body thanks to Kaatsu-Walk Training (walking with BFR).
Only two years after the study by Takashi Abe and colleagues in 2010, in a trial by Takada et al.,
2012 [37] they reach the clear conclusion that indeed, the metabolic stress generated by BFR training
is a key mechanism for the adaptations that occur both in hypertrophy and strength.
In addition to the studies related to Kaatsu Walking and how it can increase muscle mass, there is
also evidence of how BFR even in the absence of exercise is able to maintain muscle mass.
In a pilot study by Saori Kakehi and collaborators 2020 [38] carried out on people whose leg is
immobilized by means of a cast, it’s seen how the group to which BFR sessions are applied manages
to reduce the loss of muscle mass significantly, compared to the group that doesn't have BFR applied.
Precisely this study by Saori Kakehi is mentioned by Brad Schoenfeld in his latest book "The
MAX Muscle Plan" published on October 1, 2021. When Schoenfeld talks about the role of metabolic
stress and how intriguing and unknown its role in hypertrophy still is he mentions Saori Kakehi's study
as an example of how little we really know about how metabolic stress alone even in the absence of
exercise can mediate hypertrophy processes.
Actually, Saori Kakehi's 2020 study [38] is not the first to demonstrate that with the application of
BFR muscle atrophy can be decreased even in the absence of exercise. In fact, it’s already 20 years
since Takarada and colleagues [39] demonstrated that simply adding BFR sets in the absence of
exercise resulted in a decrease in disuse atrophy. In Takarada's 2020 trial, BFR without exercise was
applied to patients after anterior cruciate ligament surgery and resulted in a significant decrease in
disuse atrophy in the BFR group compared to the control group.
Since in the study by Saori Kakehi [38] and Takarada [39] BFR was applied in the absence of
exercise, the contributions of a localized metabolic response due to increased muscle activity is totally
unlikely since no exercise was performed. Thus, the processes by which atrophy is reduced are
completely unknown.
What we do know is that these processes aren't related to increases in myofibrillar protein
synthesis because Nyakayiru et al. in 2019 [40] demonstrated that BFR only increased MPS when
combined with exercise.
Myokines (Interleukin-6)
A myocine or myokine is one of several hundred cytokines or other small proteins and
proteoglycan peptides that are produced and released by muscle cells in response to muscle
contractions.
Another reason why metabolic stress might influence muscle growth would be by up-regulating
anabolic myokines, or down-regulating catabolic myokines, or both at the same time [41].
In any case, the evidence in this regard is still contradictory and the relationship of myokines with
the hypertrophic response is not entirely clear, so more research is needed in this regard.
Hypoxia, Ischemia (Low Oxygen), and ROS
During a set with blood flow restriction the lactic acid that forms in the muscle leads to a localized
decrease in the pH of the muscle tissue, and a much more acidic environment is therefore generated
in the tissue. This is what causes the burning sensation during the last repetitions of a set.
This burning sensation is due to the accumulation of metabolites and by-products such as lactic
acid, which reduces the muscle's ability to adequately use the available oxygen, ultimately leading to
muscle fatigue.
The muscle fibers that are rapidly depleted by BFR due to low oxygen levels are the red or slow
twitch fibers (type I fibers).
The red fibers are the most resistant to fatigue, precisely because they're highly dependent on
oxygen, so in a hypoxic environment they fatigue very quickly.
Since during BFR training the red fibers fatigue quickly and aren't able to produce the necessary
force, recruitment of the higher threshold motor units that innervate the fast type II fibers (the white
fibers) begins much earlier.
In terms of motor unit recruitment and fiber activation, it’s most likely the rapid activation of the
white fibers that makes the biggest difference between BFR training and conventional training.
Thus, we've that the condition of ischemia or decreased blood circulation leading to reduced
oxygen and nutrients reaching the cell, acts as a potent mediator of metabolic stress and increases
anabolic myokines during exercise. While it’s true that the duration of these elevations in anabolic
myokines is transient, and these increases return to normal values after approximately 30 minutes
after cessation of training, as could be seen in the study by Shill et al. 2017 [42].
IL-6 has been shown to be one of the first inflammatory cytokines, which are produced in the
early stages of exercise-induced muscle damage [43]. In the study by Shill et al. it’s observed to
remain elevated even 24 hours after training with loads.
Greater acute increases in growth hormone have also been seen following training under
ischemic conditions (Pierce et al. 2006) [13].
And in the study by Takarada et al [15] with BFR training, very high growth hormone increases
were observed. Even higher than those seen in the trial by Kreamer and colleagues [44], in which a
typical bodybuilder's pump and metabolic stress training was performed with a one-minute rest
between sets in search of the highest possible hormone peaks.
Many of the studies investigating training with loads under hypoxic conditions provide a fairly
clear relationship between metabolic stress and muscle hypertrophy.
In 2012 Kon et al [45], found how breathing 13% oxygen during a protocol with loads of 50% of
1RM with short rest intervals between sets (- 1 minute), significantly increased blood lactate levels
compared to the same routine performed under normoxic conditions. This demonstrates once again
that hypoxia increases and favors the accumulation of metabolites [45].
There are also several studies showing that hypoxia enhances the hypertrophic response to
weight training. Nishimura et al [46], saw significant increases in elbow flexor cross-sectional area
when 4 sets of 10 repetitions at 70% of 1RM were performed under acute hypoxia compared to a
normoxic condition [46].
ROS (reactive oxygen species)
Reactive oxygen species (ROS) released during hypoxic conditions are also involved in a variety
of signaling responses, thus providing another possible mechanism to explain the potential for
hypertrophy provided by hypoxia and elevated metabolic stress [47].
However, it should be kept in mind that the way in which hypoxia is generated may cause different
muscle adaptations, probably for that reason some studies such as that of Friedmann et al [48], have
failed to demonstrate increased hypertrophy under hypoxic versus normoxic conditions.
To try to understand why the study by Friedmann et al. found no difference between the group
that trained under hypoxic conditions versus the group that trained under normoxic conditions, we've
to look at the fact that the hypoxia in Friedmann's trial was produced by reducing the oxygen in the
room (normobaric hypoxia), and although occlusion bands were used, the restriction of blood flow
mediated by the bands was very low because, as the authors themselves indicate, the pressure
exerted by the bands was very low, that is, the hypoxia wasn't localized.
Increased activation of fast twitch fibers
Fast twitch fibers are responsible for fast and explosive contractions, and are activated by high
intensity training close to muscle failure.
When the goal is to build muscle mass, it’s crucial to use high loads that recruit the higher
threshold motor units quickly to achieve activation of the white fibers. Another option to achieve the
recruitment of high threshold motor units and thus stimulate the fast fibers would be to use a medium
or light load, but bring the sets very close to failure or to failure, and by the principle of Henneman will
be recruiting the motor units sequentially until recruiting the UM of higher threshold and thus the total
activation of the white fast twitch fibers (type II fibers).
In any case, when we want to increase muscle mass, it’s necessary to recruit the high threshold
motor units and activate and exhaust the white fibers, since it’s precisely the fast fibers that have a
much greater growth potential.
What the scientific evidence shows repeatedly to be the case with BFR training is that when
training with blood flow restriction the fast fibers are activated and properly stimulated even at low
loads.
This is mainly due to the accumulation of metabolites (metabolic stress), increased lactic acid
accumulation and low oxygen. In this scenario, what happens is that the slow twitch fibers can't get
enough oxygen, and this causes them to be exhausted more quickly and it’s necessary to activate all
the fast twitch fibers, as happens when much heavier loads are used.
The difference is that with BFR training this happens with much lighter loads. This means that
with blood flow restriction training, maximum fiber hypertrophy can be induced without the rest of the
passive structure such as tendons, ligaments, and joints having to endure as much stress and fatigue
or even some degree of damage that can be caused by excessively high loads.
When we strength train, but we do so use a light load, a relatively small number of muscle fibers
are recruited, since it’s not necessary to activate all the fibers to perform strength work such as pulling
or pushing when we're moving a light load.
Keep in mind that each muscle is innervated by hundreds of motor units, and each motor unit
innervates a specific type of muscle fibers. The motor units can work separately depending on the
muscle's need to apply force.
Thus, a light stimulus will produce a contraction that will recruit a smaller number of small or low
threshold motor units. Whereas a larger stimulus, such as that produced by applying a high force,
requires a more intense contraction that demands the recruitment of more motor units, especially the
larger or higher threshold motor units.
During training with light loads and BFR there is a greater accumulation of lactic acid, which
results in greater recruitment of motor units. Our muscles recruit both low threshold (small MU) and
high threshold (large MU) motor units.
Larger MUs innervate much denser muscle fibers that under normal conditions would only be
recruited at very high loads. However, numerous studies have shown that there is a direct link
between lactic acid accumulation and the recruitment of high-threshold motor units.
This is where BFR training comes into play, what happens BFR is that in response to excess
lactic acid generates more pronounced muscle fiber activation, especially by increasing the activation
of fast twitch muscle fibers (the white fibers).
Under normal conditions training with light loads doesn't recruit fast twitch muscle fibers. These
muscle fibers are activated only when the muscle has to perform explosive movements, manage high
loads, or when the slow fibers are already exhausted or don't have sufficient oxygen supply.
However, fast twitch muscle fibers, unlike slow twitch muscle fibers, don't depend on oxygen for
energy, which is why they can continue to produce force despite being in a state of hypoxia or oxygen
deprivation.
Precisely what triggers the early activation of fast fibers with BFR training and light loads is the
fact that the restriction of blood flow deprives the slow twitch fibers of oxygen, thus requiring the fast
twitch fibers to start up to continue performing the task.
It’s mainly for that reason that some researchers, such as Meyer or Loenneke [34] [49], suggest
that the main factor by which BFR training produces hypertrophy is by activation of the white fibers.
This is undoubtedly a very important factor, but as we will see later it’s not the only one, since with
BFR training there are also important hormonal alterations, which include increases in muscle protein
synthesis (MPS) and IGF-1, as well as increased proliferation of myonuclei among many other factors
that we will see in the book.
We also know, and it has been widely demonstrated that even with very light loads with BFR the
activation of fast twitch fibers (type IIA and IIX fibers) will be high as long as the sets is taken to
muscle failure.
Some studies have proven this using various techniques. Takazawa, et al., 2000 [17] did it using
electromyography (EMG), it has also been proven by Ingemann-Hansen glycogen depletion [50], and
also by organic phosphate (Suga et al., 209, 2010) [51][52].
In all cases it has been seen that an increased activation of fast twitch fibers (type II fibers)
occurred with BFR training.
This leads some researchers to think that despite everything, the increased activation of type II
white fibers, could be the main pathway or the main factor by which BFR training causes increased
anabolism (Loenneke et al., 2011) (Meyer, 2006) [34][49].
Thus, it appears that recruitment of white fibers is the major factor for hypertrophy and this
recruitment is in turn associated with metabolic stress. But everything seems to indicate that there are
other factors that most probably also play an important role.
In a study by Suga et al [51] showed that only 31% of the subjects who trained with BFR at 20%
of 1RM recruited all the fast twitch fibers during training, whereas 70% of the subjects who trained
without BFR with a load of 65% of 1RM recruited the fast twitch fibers.
If we take into account that on the one hand in the study by Suga et al [51] it was seen that with
an intensity of 20% of 1RM and with BFR only 31% of the subjects managed to recruit the white fibers,
but on the other hand training with BFR has been shown to generate hypertrophy at intensities of 20%
of 1RM in a manner equal or superior to training with loads at higher intensities as was seen in the
trial by T. Yasuda et al. 2005 [53] and Laurentino et al. 2012 [54] where extremely light loads were
also used. Everything seems to indicate that the anabolic effects of BFR training can't be explained
solely by the recruitment of white fibers.
In any case, that hypertrophy with BFR training is not only due to increased recruitment of white
fibers is supported by several investigations showing EMG activations in a larger area of muscle
tissue when exercise is performed at higher loads near 80% of 1RM, than at 20% of 1RM even when
using BFR, indicating that there is a smaller EMG activation when at lower intensities as found by
Manini and Clark [55].
Other more recent research also shows greater muscle activation with sets using higher
loads even though metabolite accumulation is much greater during sets with lighter loads [56][57][58].
In any case, it should be kept in mind that electromyography only provides information about
the neural impulse, which encompasses not only fiber recruitment, but also impulse velocity, timing,
muscle fiber propagation velocity and intracellular action potentials [59].
From all this, the conclusion we can draw is that, although it’s true that training with BFR with only
20% of 1RM can achieve gains in hypertrophy and strength.
Perhaps these gains in hypertrophy and strength could be improved if, instead of using loads of
20% of 1RM, loads of 40% of 1RM were used, better results would be obtained, since with greater
intensity there would also be a greater recruitment of fast fibers.
After all of the above and anticipating a little bit to the part in which we will go into detail with the
training. My recommendation regarding the loads to use with BFR training would be to use loads
closer to 40% of 1RM with which we can perform 20/25 repetitions in the first set and not loads of 20%
of 1RM in which we can perform more than 30 repetitions.
It must be considered that in the studies loads of 20% are used many times with good results. But
just because they're good results doesn't mean that they're optimal.
In addition to the percentage of 1RM to be used with BFR training, a very important point to take
into account is the occlusion pressure. Cerqueira and collaborators in a recent meta-analysis
published on July 26, 2021 [60], showed that in order to produce a greater activation of type II fibers
and to anticipate the total recruitment of type II fibers and thus muscle failure, a pressure of at least
50% is necessary if the pressure is less than 50%, this greater recruitment of type II fibers doesn't
occur.
In any case, achieving a pressure of 50% is not a problem, it’s normal to train with a pressure of
approximately 60% in the arms and can reach 70% for the legs. Calculating the pressure level
subjectively is not at all complicated and is something we will see a little later.
Cellular Swelling
Another reason why greater hypertrophy occurs when training with blood flow restriction is used
could be due to a greater accumulation of intracellular fluid, which we know as congestion or "pump".
As the muscle is exercised during contraction, the muscle pushes all this accumulated fluid to the
sides, and in the eccentric phase of the movement, when the muscle relaxes the contraction all the
fluid rushes into the cell.
Along with all this accumulation of liquid there is also an accumulation of metabolites and the cells
of the muscle tissue begin to swell.
As the cells increase in size, additional stress is generated in the cell which leads to the activation
of a protective mechanism which allows the cells to adapt and grow in order to be able to withstand
the new pressure to which they're being subjected.
In response to these threats and in order to be repaired or "reinforced" the cells perform a set of
anabolic processes including a further increase in protein synthesis, and in addition various catabolic
processes are down-regulated in an attempt to make the muscle cell larger, stronger and more
resistant [61].
The role of metabolic stress and cell swelling in hypertrophy has long been questioned [62], but
it’s becoming increasingly clear that it does play an important role and this role is even more evident
when BFR training is employed [63].
While there are still connections and mechanisms that aren't yet fully understood, the relationship
of metabolic stress and cell swelling with hypertrophy is taken for granted according to Freitas et al
2017 [63].
What's not entirely clear is whether increased angiogenesis (increased formation of new blood
vessels) and increased mitochondrial biogenesis also occur.
Hormonal Factors - Increases in Testosterone, GH and IGF-1
We also know that growth hormone (GH) plays an important role in muscle recovery.
However, everything points to the fact that the role of growth hormone is not focused on building
muscle mass as commonly believed, but rather plays an important role in the regeneration of muscle
collagen and tendons, as pointed out by the research of Kurtz et al., 1999, Doessing et al., 2010, and
Boesen et al., 2014 [64][65][66].
In fact, we know that even exogenously administered growth hormone hasn't been shown to
influence muscle mass and strength gains according to the results of the meta-analysis of Sergeeva,
Miroshnikov, and Smolensky [67].
In the 2019 Sergeeva, Miroshnikov, and Smolensky meta-analysis [67], all studies to date in
which growth hormone had been used for the purpose of gaining muscle mass and strength were
reviewed.
In some of these studies, the amounts of hormone used were quite high, higher even than those
used by some professional bodybuilders. However, in none of the studies were strength or
hypertrophy gains observed.
What was observed was increased water retention (which some bodybuilders mistake for gains),
as well as positive adaptations in tendon stiffness, but none of the studies reported strength or
hypertrophy gains from growth hormone.
Although bodybuilders continue to spend a lot of money on growth hormone in order to increase
the size of their muscles, the truth is that it hasn't been shown to be useful for gaining muscle mass or
strength, rather everything points to the contrary.
We do know that growth hormone has positive effects on fat loss and recovery, so that indirectly it
could help muscle mass gains to be more optimized due to less fat accumulation and greater recovery
that could be used to increase training volume and intensity, thus causing better adaptations of
hypertrophy and strength, but that in no case would be directly attributable to the administration of
growth hormone.
Regarding hypertrophy or strength gains directly due to the use of growth hormone, to date there
are absolutely no studies in which hypertrophy and strength gains have been obtained with it [68].
As for possible increases in strength thanks to growth hormone, these have not been seen either,
but better adaptations in tendon stiffness have been seen and a stiffer tendon is able to transmit force
better, so indirectly some strength could be attributed to growth hormone, but as with gains in muscle
mass, these gains would occur indirectly due to improvements in tendon stiffness.
Although we've no evidence to support the use of growth hormone for the purpose of increasing
muscle mass, some bodybuilders report hypertrophy gains with its use.
Almost certainly what actually happens is increased fluid retention, which is a very common
occurrence with growth hormone administration. So, in any case we would be talking about
sarcoplasmic hypertrophy (temporary) due to a greater intramuscular water retention that will
disappear when discontinuing the use of the hormone.
In the following chapters we will see how training with blood flow restriction affects the hormonal
level in terms of growth hormone peaks, IGF-1, testosterone and other equally or more interesting
hormonal factors and how these could lead to positive adaptations.
Growth Hormone Increases
There has been much speculation as to whether the acute elevations of anabolic hormones such
as growth hormone or IGF-1 that occur after loaded exercise when a large accumulation of
metabolites is generated could augment the hypertrophic response.
There is much controversy as to whether the peaks in testosterone, growth hormone, and IGF-1
that occur after strength training can have any influence on hypertrophy and strength adaptations, and
so far, the answer seems to be negative.
Although it has not been possible to clearly relate these peaks to hypertrophy adaptations, the
fact that it has not been possible to demonstrate a clear relationship doesn’t necessarily mean that it
should be ruled out; it may be that there is a relationship and now it’s simply not known. Or maybe
there is no relationship after conventional strength training, but what happens when those peaks are
up to 10 times higher?
We know from multiple studies that metabolic stress is the factor that is most strongly associated
with an increase in growth hormone levels after training (Gordon et al., 1994)(Gotshalk et al., 1997)
(Ahtiainen et al., 2004) (Pierce et al., 2006) (Takano et al., 2005) (Takarada, Nakamura, et al., 2000)
[10][11][12][13][14][15].
It has been believed for many years (Gordon et al. 1994 and Ahtiainen 2004) [10][12], that postexercise growth hormone elevations are mediated by increased accumulation of lactate, hydrogen
ions, or both.
In fact, it has been shown that individuals lacking myophosphorylase, which is a glycolytic
enzyme responsible for breaking down glycogen and thus inducing lactate production, demonstrate a
greatly attenuated growth hormone response after exercise (Godfrey et al., 2009) [69]. This fact
provides us with strong evidence that there is a link between lactate production and GH release.
During BFR training a metabolite-induced decrease in pH occurs, it may also increase growth
hormone release through stimulation of intramuscular metaboreceptor-regulated chemoreceptors and
afferent fibers of groups III and IV (Loenneke, Wilson and Wilson, 2010) (Viru et al., 1998) [70][71].
On the other hand, the accumulation of lactic acid is something that happens with both high and
light loads. What we do know and what has been amply demonstrated is that if training with light loads
is with BFR it triggers a greater release of growth hormone (Gordon et al., 1994) (Takarada,
Nakamura, et al., 2000) (Godfrey, Whyte and Head, 2005) [10][15][72].
These greater increases in growth hormone with BFR training can be summarized in this way.
While the muscle is being used, the nerve endings within the muscle are stimulated along with the
muscle fibers, logically the fibers aren’t stimulated if they don’t receive a command from the nerve
endings.
During intensive use and together with an increased accumulation of lactic acid, these nerves
stimulate the pituitary gland to release growth hormone. This results in training with restricted blood
flow even at light loads to generate a response that significantly increases growth hormone levels.
This has been known for a long time. As early as 2000 Takarada and colleagues [15],
demonstrated that training with low loads and BFR generated growth hormone peaks up to 290%
higher than when measurements were performed at rest, and 1.7 times higher than the peaks
observed in training with metabolic-type loads but without BFR [44].
And if that were not enough, in 2007 Fujita and colleagues [73], reported up to 10-fold increases
in growth hormone levels when training with BFR compared to training of similar intensity but without
BFR.
We’re talking about up to 10-fold increases with BFR training compared to training with non BFR
loads.
The spikes may not have any relevance to muscle mass gains, but they may have another
restorative function. It could be that these increases in growth hormone are related to the
improvement in soreness and injury experienced with BFR training.
IGF-1 Increases
BFR training not only produces higher spikes in GH, but also in IGF-1 (insulin-like growth factor),
and these increases in IGF-1 may indeed significantly affect muscle growth.
In fact, some research points to IGF-1 as a major regulator of muscle growth. In this regard, we
have research such as that of Hameed et al (2004), Kostek et al (2005), or Stewart and Pell (2010)
[74][75][76]. And several studies have demonstrated a significant increase in IGF-1 levels when BFR
is incorporated as part of a training program (Abe et al., 2005) (Fujita et al., 2007) [77][73].
Regarding increases in GH and IGF-1 levels with BFR training, very significant differences in
acute increases in GH and IGF-1 levels have been seen in different trials such as Abe et al., 2005,
Fujita et al., 2007, Takano et al., 2005 or Takarada, Nakamura, et al., 2000 [77][73][14][15].
Increases in IGF-1 after BFR training
Since growth hormone is known to potentiate IGF-1 secretion, it seems logical that the
accumulation of metabolites that cause increases in growth hormone would also be associated with
increased IGF-1 levels after exercise.
This has been confirmed to some extent by studies showing significantly increased IGF-1
elevations after metabolically fatiguing routines (Kraemer et al., 1990) (Kraemer et al., 1991) (Rubin et
al., 2005) [44][78][79].
Several studies reporting acute increases in IGF-1 levels have been performed under BFR
training conditions (Abe et al., 2005) (Fujita et al., 2007) (Takano et al., 2005) [77][73][14]. This
suggests that the results in increases in IGF-1 levels are largely mediated by metabolic stress.
It should be noted that the research is specific to the circulating IGF-1 isoform. Therefore, it
doesn’t necessarily mean that these increases are also extrapolable to intramuscular IGF-1 levels.
90% of circulating IGF-I is of hepatic origin and can have autocrine, paracrine, and endocrine effects,
the latter being the only ones that could have effects on skeletal muscle tissue.
In other words, these increases in IGF-1 may have no effect on skeletal muscle tissue. Although
it’s also likely that they do, it has not been proven or completely ruled out so far.
It’s for this reason that many researchers are still not entirely clear whether transient postexercise hormonal spikes have any effect on hypertrophic adaptations.
According to some researchers, if hormonal spikes do exert any effect on hypertrophy, it would be
of small caliber, and would not contribute significantly to metabolite induced anabolism.
However, it remains unexplained how it’s possible for a group of men to gain muscle mass in the
quadriceps simply by walking with BFR [35] or how the simple use of BFR even in the absence of
exercise can reverse muscle mass loss in an immobilized limb [38].
The first research on Kaatsu-Walk Training that demonstrated increases in muscle size by
walking with blood flow restriction was that of Abe, Kearns and Sato in 2006 [36] and to this day the
processes by which such hypertrophy is generated are still unclear.
The most curious thing is how some researchers who think along the lines that metabolic stress
doesn’t play a role in hypertrophy, completely ignore studies where hypertrophy is obtained without
mechanical stress and don’t cite them in their books. Or when they do it’s very much in passing in an
anecdotal way.
It’s also true that some of the trials showing improvements in muscle mass simply by using BFR
bands are very recent [38].
In fact, researchers like Brad Schoenfeld who barely devotes space in his books to BFR training,
already in May 2021 recommends in a post the use of BFRT to achieve red fiber hypertrophy when
the training goal is muscle mass gains. And in his latest book called The M.A.X. Muscle Plan 2.0
published in October 2021 when he talks about metabolic stress he points it out as the most intriguing
factor of all, since the relationship with hypertrophy is still not fully understood, but he cites a study
with BFR from 2021 in which it manages to reduce the loss of muscle mass in the absence of exercise
and implies that perhaps we should rethink the role of metabolic stress in hypertrophy, since it doesn’t
seem to be as useless after all as we have been thinking lately.
Undoubtedly, in time, many more researchers will have to rethink some things regarding the role
of metabolic stress.
From my point of view, and based on all the research that is emerging, it’s quite clear that
metabolic stress when BFR is used plays a relevant role in hypertrophy processes, as there aren’t few
studies in that sense. But elucidating the exact mechanisms by which metabolic stress mediates
hypertrophy is a complicated task and now only some of them are known.
It should be borne in mind that the three factors involved in hypertrophy (mechanical tension,
muscle damage and metabolic stress) almost always occur at the same time, so it’s very difficult to
investigate them separately.
The problems that exist and those researchers encounter when investigating metabolic stress,
mechanical strain, or muscle damage in isolation, I mention in the chapter dedicated to metabolic
stress in the free hypertrophy course on YouTube.
If you want to see the free hypertrophy course I have posted on YouTube, you can put
"hypertrophy course" in the YouTube search engine and you will get the playlist with all the chapters.
What we do have a pretty clear idea of is how thanks to metabolic stress the high threshold motor
units are recruited earlier and also several processes by which metabolic stress aids and mediates
hypertrophy are documented.
But when it comes to BFR training there are still some things that escape us and are difficult to
explain, such as the increased hypertrophy that occurs in slow type I fibers (Bjørnsen et al., 2018)
(BjØrnsen et al., 2019) (Jakobsgaard et al., 2018) [80][81][82].
This hypertrophy of type I fibers occurs significantly only when working with light loads and BFR,
it doesn’t occur with light loads without BFR.
Testosterone increases
In terms of acute increases in testosterone, BFR training has generally failed to show significantly
higher elevations in testosterone than can be obtained with training without BFR.
It thus appears that in terms of acute increases in testosterone levels BFR training doesn’t offer
significant differences as seen in the trials of Fujita et al., 2007, Reeves et al., 2006, Viru et al., 1998
[73][83][71].
In any case, and even if anecdotally, we should also mention the Cook, Kilduff and Beaven trial of
2014 [84], in which significant increases in testosterone levels were seen.
Although higher testosterone peaks were not recorded in several previous trials, significant
increases in testosterone were seen in this trial by Cook, Kilduff and Beaven. The trial authors raise
the possibility that such high testosterone peaks may have occurred because the loads used with BFR
were higher than in previous trials.
In the Cook, Kilduff and Beaven study, the loads used were 70% of 1RM, whereas in the previous
BFR trials where such high peaks were not seen and the loads used with BFR were typical of those
used in BFRT studies, which are usually at most 40% of 1RM, making them much lower loads [83][27]
[85][71].
Another option considered by the researchers is that the difference in the results with respect to
previous trials could be due to the fact that the sampling methodology (saliva or plasma) was different.
Since, in the Cook, Kilduff and Beaven trial the samples were taken from saliva and in the previous
studies the samples were taken from blood plasma.
Activation of mTORC1 and muscle protein synthesis
Simplifying the process, we could say that bringing a muscle-to-muscle failure or very close to
failure results in the activation of several anabolic processes, among which we could highlight the
mTORC1 activation pathway.
The mTORc1 pathway could be understood as a switch that activates the whole process of
muscle protein synthesis necessary to repair damaged tissue or to generate new muscle tissue (new
contractile protein).
When a fiber is overused and a certain degree of damage occurs, the mTORC1 pathway comes
into play and is responsible for repairing or strengthening that fiber by adding new sarcomeres.
Taking the muscle-to-muscle failure or very close to failure can have some drawbacks. When the
muscle is brought to muscle failure, very high fatigue is generated in both the connective tissue and
the CNS, and in addition, excessive muscle damage can occur that could result in the entire process
of creating new tissue remaining simply a repair process.
Fortunately, BFR training doesn’t require lifting excessively high loads to bring the muscle to
failure, so that much of the fatigue in the connective tissue that we’re not interested in, we’re spared.
Furthermore, some studies such as that of Abe et al., 2005 or Takarada, Nakamura, et al., 2000 [77]
[15], show that with BFR training with loads between 20 and 50% of 1RM muscle damage is minimal.
Regarding mTORC1 levels, we have that with training with light loads and BFR, there are
numerous studies that have shown that training with light loads, but with BFR, results in an increase in
mTORC1 levels. Increases of up to 46% more muscle protein synthesis have been seen three hours
after training with loads when BFR was used. This has been seen in studies such as Mitchell et al.,
2012, Fujita et al., 2007, Fry et al., 2010, or Gundermann et al., 2014[86][73][87][88].
Thus, we can see that the scientific literature currently available to us has shown that BFR
training improves anabolic signaling and muscle protein synthesis (Fry et al. 2010) [87], and thus
markedly increases muscle growth as seen in the meta-analysis of Loenneke et al [31], and all this
despite the fact that loads were used that in non BFR circumstances would be considered too low to
generate a significant hypertrophic response of the fibers [89][90].
For many researchers, increases in protein synthesis could be one of the main mechanisms to
explain the adaptations associated with BFRT.
It appears that BFRT produces increases in protein synthesis by altering biomolecular pathways,
including the mammalian target of rapamycin complex 1 (mTORC1), and inhibition of atrogens such
as Muscle RING Finger1 (MuRF1), atrogyn-1 and myostatin (MSTN).
In this regard, very high SPM increases have been seen even with a single session of BFRT.
Specifically, it was the team of Fry et al [87] who found that a single session of BFRT with loads of
20% of 1RM increased muscle protein synthesis by 56% compared to pre-exercise levels, as well as
increased phosphorylation of the mTORC1 target ribosomal S6 ribosomal kinase 1 (S6K1)
downstream.
Exercise with BFR has also been shown to influence the MSTN pathway, which is a downregulator of muscle growth. In this context, Laurentino et al. (2012) [54] demonstrated that 8 weeks of
BFR resistance training resulted in similar muscle size and strength gains similar to traditional highload resistance training with a concomitant decrease in MSTN gene expression.
The vast amount of research that already exists on light-load training and BFR has led to some
groundbreaking discoveries regarding muscle growth.
In response to the overwhelming evidence from these studies, Dr. Ronald Meyer, a physiologist
at Michigan State University stated that hypertrophy is a reaction to metabolic signals associated with
anaerobic conditions, meaning restricted or absent oxygen. [49].
Myostatin reductions
A small part of BFR research focused on testing for effects on the downregulation of myostatin.
Myostatin is a protein found naturally in our bodies whose function is to slow down muscle
development and growth, thus delaying the development of muscle stem cells. Muscle stem cells are
the muscle satellite cells, and are necessary for the regeneration, growth, and maintenance of muscle
mass.
In other words, an increase in myostatin would favor a decrease in muscle. While a decrease in
myostatin would favor an increase in muscle.
You may have seen pictures of a breed of hyper muscled cows and bulls. This is a breed of cattle
called Belgian Blue. This breed of cattle has a natural mutation that inhibits the protein myostatin,
which is responsible for limiting muscle development and interferes with fat accumulation, resulting in
huge cows and bulls with a large amount of muscle mass and very lean meat with hardly any fat.
This type of mutation that inhibits myostatin sometimes also occurs in other animals such as cats,
dogs, sheep, pigs, kangaroos, etc.
Some of these gene modifications have been made in the laboratory, such as the modification or
deletion of myostatin by a team of Chinese scientists modifying the Beagle dog breed, to create
specimens that have twice the muscle mass. The objective creation of this new breed of dog was to
create improved dogs that could perform police and military tasks. The group of researchers hopes to
be able to modify the genetics of other breeds and to continue advancing in the analysis and
treatment of diseases such as Parkinson's or muscular dystrophy.
As far as we’re concerned, which is its role in the gains (or not) of muscle mass, it’s now known
that myostatin levels decrease in response to exercise. The body creates an environment conducive
to muscle growth. This usually only occurs under high load training conditions (Roth et al., 2003)
(Forbes et al., 2006) (Hill et al., 2003) (Willoughby, 2004) [91][92][93][94].
However, researchers have shown that when BFR training and very light loads are used, very
similar decreases in myostatin occur to those seen with training at much higher loads. In this line of
research we have for example the Laurentino trial [54].
In fact, in the study by Laurentino et al [54], the decrease in myostatin was slightly greater in the
BFR group. This group obtained a decrease of 45% compared to 41% in the group without BFR.
It should be noted that strength improved by 40.1% in the group without BFR while in the group
with BFR it was 36.2%. This is a fact to be taken into account, although it’s obvious that when training
with heavier loads, better adaptations will be obtained in maximum strength closer to 1RM, while using
lighter loads the adaptations in strength will occur at high repetitions.
In any case, it should not be forgotten that one of most determining factors for strength is the
muscle cross-section size, so that in the medium and long term, a larger muscle will always be
capable of applying more force.
Several studies have been conducted to determine how BFR training affects the decrease in
myostatin, as well as its effects associated with gains in muscle mass and strength, such as that of
Gualano et al. in 2010 [95], or Santos et al. in 2014 [96], and in both studies the conclusions are along
the same lines as what was seen in the Laurentino trial. When BFR is applied in training, myostatin
reductions occur even when light loads are used, and these reductions don’t occur when training is
without BFR and light loads.
Muscle damage with BFRT
There is research that suggests that BFRT with loads ranging from 20% to 50% of 1RM, produce
minimal muscle damage, in this line we have the studies of Abe et al., 2005 or Takarada, Nakamura,
et al., 2000 [77][15]. There are also interventions such as that of Wilson and collaborators [26], where
they conclude that BFR training significantly increases muscle activation and hypertrophy without
increasing the rates and markers of muscle damage.
Wilson's November 2013 study is quite relevant because they finally stopped using the inflatable
cuffs that had been used in all studies and employed more economical BFR bands. Also, we have that
the exercise they tested on in the Wilson study was the leg press exercise and it was not an analytical
exercise. The leg press is an exercise that tends to generate quite a bit of muscle damage.
It should be taken into account that the intensity used in Wilson's trial was 30% of 1RM, but the
sets led practically to muscle failure, so that it was observed that there was attenuated muscle
damage is quite interesting, since by leading the sets very close to failure the recruitment of motor
units and the stimulation of the fast twitch fibers is complete, and yet muscle damage was greatly
reduced.
Other research such as that of Takarada, Nakamura et al [15] found that, although the markers of
muscle damage were largely attenuated, some degree of microdamage within the myofibrils could be
observed at the end of BFR training.
Some degree of muscle damage is normal and not necessarily bad, as a certain amount of
muscle damage can indirectly benefit muscle development [97]. In any case, muscle damage and
subsequent delayed muscle soreness (DOMS or stiffness) is by no means a prerequisite for muscle
development. Muscles, connective tissue and immune system become increasingly efficient in dealing
with the muscle damage produced in intense training and a phenomenon called "repeated attack
effect" is generated, which is basically an adaptive response to muscle damage [98].
After repeated muscle damage and with the aim of increasingly reducing muscle damage and the
DOMS associated with such damage, several physiological and structural adaptations occur whose
function is to gradually reduce the sensation of pain. In general terms and in summary, what happens
is that the more you train and at higher levels of intensity, the greater your tolerance to muscle
soreness, even if you inevitably inflict a small amount of damage to the fibers.
This is why some of the best bodybuilders in the world never feel DOMS after an intense workout
but show impressive musculature. Therefore, you should not judge the quality of a workout based on
the level of DOMS you feel afterwards.
Also, keep in mind that too much delayed muscle soreness can be detrimental to muscle growth.
If you are so sore to the point that it causes you pain to sit up or raise your arms above your head, you
may have outgrown your body's ability to repair damaged muscle tissue, and that would mean that
resources aren’t being allocated to generating new contractile protein.
There is speculation that there may be a sweet spot where a moderate amount of muscle
damage may help in the process of generating muscle hypertrophy, while substantial damage would
negatively affect the growth response.
In fact, it’s known that excessive muscle damage will be counterproductive in terms of muscle
mass gains since muscle protein synthesis will go towards repairing the damaged tissue, something
that has been seen in numerous studies of untrained people in which excessive initial muscle damage
didn’t produce hypertrophy gains, and it was not until the fourth or fifth week when muscle damage
began to be reduced and adaptations and hypertrophy gains began to be generated. This may lead us
to think that a certain degree of muscle damage is interesting and perhaps necessary, but excessive
muscle damage is counterproductive to hypertrophy gains.
On the other hand, there are also investigations in which it has been seen that even with light
loads, BFR training caused considerable muscle damage and especially muscle soreness of late
onset (stiffness), as well as prolonged decreases in maximum voluntary contraction, and elevated
sarcolemma permeability. In this line we have the studies of Wernbom et al., 2009 Wernbom et al.,
2012 and Farup et al., 2015 [99][100][101].
Nevertheless, with these data we can think that muscle damage with BFR and light loads and
taking the sets to failure or very close to it, is somewhat less (or at most equal) to the muscle damage
that occurs when training without BFR and also taking the sets to muscle failure or very close to it
[102][103][104][105].
Most likely, that the muscle damage with BFR is less is since the training loads are typically low
(i.e., 20 to 50% of 1RM), those loads aren’t high enough to induce substantial mechanical stress.
However, the possibility of muscle damage and even episodes of rhabdomyolysis in response to BFR
has not been completely ruled out and is still debated in the scientific community (Loenneke et al.,
2014b; Burr et al., 2020; Wernbom et al., 2020) [106][107][108].
It should be borne in mind that these favorable results with the BFRT have been obtained in
studies with totally controlled conditions (band pressure, loads and times of use); in daily use, some of
these conditions aren’t easily controlled, so above all, caution should be exercised in the event that
one wishes to begin with the BFRT.
What seems clear is that both with and without BFR exactly the same thing will happen, i.e., the
level of muscular damage that the muscles receive will depend on the level of athlete adaptation. A
person who’s not used to a certain type of training is going to have more muscle damage and more
delayed muscle soreness than a person who’s adapted to a certain type of training and has at least
partially developed the repeated attack effect [98].
For this reason, to avoid excessive muscle damage and stiffness, which would not be convenient
with the objective of obtaining hypertrophy gains, the most advisable thing to do is to start training with
BFR in a progressive manner, both in the level of pressure and in the duration in time that BFR is
used, as well as in the volume of sets and the intensity of these.
It must be understood that the objective of our workouts should not be to generate muscle
damage, nor a large amount of delayed muscle soreness (stiffness). Although the evidence indicates
that BFR is very likely to produce less muscle damage, if you start training with BFR in the same way
and with the same intensity as you train without BFR, it’s more than likely that you will not be adapted
to the new work demands and you will surely generate a large amount of muscle damage and delayed
muscle soreness (stiffness), so to avoid excessive muscle damage follow the indications given in the
chapters explaining how to start using BFR training and start using BFR in a prudent and progressive
manner.
We could go on and on reviewing scientific studies and the evidence will continue to support BFR
training for muscle mass gains, in fact, we will review some later but for now let's wrap up this chapter
on the mechanisms of hypertrophy with BFR and move on to more practical things.
So far we have reviewed some the most important research that provides a good amount of
information and explains why blood flow restriction training is so effective.
Now, what we need is a practical guide on how to use occlusion bands and how to train with them
for maximum muscle mass gains and we'll get to that shortly, but first we need to understand the
adaptations that occur with BFR training and the risks and contraindications to be aware of before we
start training with BFR.
SPECIFIC ADAPTATIONS OF BFR TRAINING
Local mechanisms (at the cellular level) of BFR Training
With restricted blood flow training (BFRT), we partially restrict the inflow of blood from the arteries
to the muscle, but we further restrict the outflow of blood from the veins, which would be the venous
return that carries the deoxygenated blood back to the heart.
This will cause several things.
In the first place, the amount of oxygen inside the muscle cell decreases, therefore, we are
producing what we would call muscular hypoxia. On the other hand, we are causing an accumulation
of metabolic products such as adenosine monophosphate (or AMP), hydrogen ions, lactate, reactive
oxygen species (ROS), and nitric oxide.
Due to this accumulation of metabolites and cellular signals, several specific responses will occur
such as stimulation of satellite cells, a stimulation of muscle protein synthesis through the mTOR
pathway, along with an increase in cellular inflammation and mitochondrial biogenesis.
In the 2021 trial by Saatmann et al [109] the mechanisms at the local (cellular) level by which
BFRT generates hypertrophy and other positive adaptations are already described quite precisely.
As verified by Saatmann et al, 2021 [109], these are the different processes that are set in motion
by BFR training.
Image abbreviations:
Ca2+: Calcium signaling is the use of calcium ions (Ca
intracellular processes.
2+)
to co-communicate and drive
CAMKII: Ca2+/Calmodulin Protein kinase II, Ca+2/calmodulin-dependent protein kinase or
CaMKII is a Serine/threonine protein kinase that is regulated by the calcium-calmodulin complex
GH: Growth hormone.
GLUT4: Glucose transporter 4.
C-Met: hepatocyte growth factor receptor, a protein that in humans is encoded by the MET gene.
HGF: Hepatocyte growth factor.
IGF-1: Insulin-like growth factor 1.
mTOR: The target of rapamycin in mammalian cells, better known as mTOR (its acronym in
English). It’s a protein present in mammalian cells that has important functions.
AMPK: An enzyme complex that is activated by an increase in the AMP-ATP ratio, it’s considered
a cellular energy detector that helps the cell's energy balance and calorie consumption.
nNOS: Nitric oxide synthase, or nitric oxide synthase, is an enzyme that catalyzes the conversion
of L-arginine to L-citrulline by producing nitric oxide from the terminal nitrogen atom of the guanidine
group of arginine.
ROS: Reactive oxygen species.
As we can see in the image, BFRT initiates several cellular processes and signaling that among
other things result in an increase in muscle mass.
In summary, what happens is that muscle contraction with BFR leads to increased Ca2+ influx
and increased activation of calcium calmodulin kinase II (CAMKII) phosphorylation in skeletal muscle,
which, together with AMPK activation, results in increased GLUT4 translocation. GLUT4 translocation
is nothing more than an increased activation of glucose transporter proteins at the cell membrane.
This process increases and enhances the uptake and utilization of glucose as an energy substrate.
The increased transport of glucose to the cell membrane together with the elevated production of
ROS are the pathways that result in increased glucose uptake independent of insulin. This is one
reasons why BFRT is so interesting in people with type II diabetes. Although improvements in insulin
sensitivity are likely to occur in all populations.
On the other hand, we have that the accumulation of metabolites results in increased growth
hormone production.
Growth hormone increases mainly due to the accumulation of lactate and hydrogen ions. It has
always been thought of lactate and hydrogen ions in a negative way, but it has been seen that
especially lactate is directly related to increases in growth hormone secreted by the pituitary (the
anterior hypophysis). Thus, this accumulation of metabolites generates above all increases in growth
hormone peaks.
These growth hormone elevations when BFR training is employed can be up to 10 times greater
than those produced with non-BFR training [73].
These increased growth hormone peaks induce increased collagen synthesis, which has a
protective and reparative effect on skeletal muscle.
On the other hand, a greater increase in GH also induces a greater release of IGF-1 as proven by
Kraemer et al. in 1990 and 1991, and later also by Rubin et al. in 2005 [44][78][79]. This increased
release of IGF-1 promotes the increase of satellite cells and allows them to fuse with existing
myofibrils.
To these amplified growth hormone peaks, we must add the signaling coming through the nitric
oxide pathway that activates satellite cells which fuse with the existing cells, thus, we are favoring a
potential increase in muscle mass.
In addition, we have that the accumulation of metabolites and lack of oxygen generates fatigue in
type I fibers, this impossibility on the part of red fibers to exert force, causes afferent neurons of group
III / IV to be stimulated, resulting in a greater recruitment of high threshold motor units and a faster
activation of fast twitch white fibers, even though the loads used in BFR training are less than 50% of
1RM.
Finally, we also have that BFR training induces cell swelling, through the entry of fluids into the
cell, which can induce several anabolic pathways by activating mTOR and AMPK at the same time.
Thus, it appears that the anabolic pathway is activated with simultaneous inhibition of catabolism.
The inhibition of catabolism occurs because with cell swelling the cell understands that it’s being
broken down and to defend itself against this aggression it deactivates the catabolic pathways.
We know that the AMPK pathway inhibits mTOR, and both processes don’t usually occur at the
same time. This has been seen especially in studies with concurrent training (aerobic and strength) as
the activation of AMPK partially inhibited the activation of mTOR.
However, what happens with blood flow restriction training is especially interesting, since both
pathways are activated at the same time, and we are favoring adaptations in both directions.
It’s not known if the simultaneous activation of both pathways could be due to a different temporal
pattern of activation, or if perhaps in an acute way aMPK is activated and then the mTOR pathway
and muscle protein synthesis are activated. At present the mechanisms aren’t entirely clear, but what
is known is that with BFR training both pathways seem to coexist without interfering too much
between the different processes of each one.
In the image we can see that the activation of mTOR and aMPK are shown with dashed lines, this
is because it’s known that both occur, but the exact mechanisms by which the two processes occur at
the same time aren’t understood, since normally they should not occur simultaneously since they are
opposites.
The trial by Saatmann et al [109] mainly investigates the mechanisms by which BFR training is
useful in improving metabolic control in patients with type II diabetes. But they also suggest that BFR
training promotes muscle hypertrophy primarily through cellular inflammation and metabolite
accumulation, these two processes resulting in increased protein synthesis.
In addition, low oxygen availability during BFR may further induce intracellular ROS production,
which may promote mitochondrial biogenesis and GLUT4 expression and thus increase insulin
sensitivity.
Thus, the evidence available to date indicates that BFR training can decrease insulin and
glycosylated hemoglobin (HbA1c) levels, while increasing GLUT4 translocation.
GLUT4 translocation is the mechanism by which glucose transport to skeletal muscle is
increased, so this could improve metabolic control in people with type II diabetes, and it’s likely that
people without any pathology would also benefit from improved insulin sensitivity with BFR training.
What has become clear from the study by Saatmann et al [109] is that the various adaptations
that occur during BFR training make it a useful and effective training method for improving muscle
function and glucose metabolism in people with type II diabetes.
Clearly, further studies will be needed to investigate the specific risks to patients with diabetes,
but so far the evidence available to us indicates that as a general rule the risks of BFR training are no
greater than those of strength training without BFR [110].
Muscular and cardiovascular adaptations
In addition to the adaptations at the local and peripheral level that we have seen in the previous
lesson, training with blood flow restriction also produces adaptations at the muscular and
cardiovascular level.
The latter (cardiovascular adaptations) are still being studied. But it’s already known that certain
types of cardiovascular adaptations are produced that are positive in terms of improving aerobic
performance.
It must be taken into account that, if on the one hand, the entry of blood flow into a certain part of
the body is being restricted, and also venous return is being reduced, what happens is that the
amount of blood returning to the heart will be less, blood since part is accumulating in the muscles
limbs to which BFR is applied, and this will cause the entire blood flow to be different.
When we use BFR training, there is not enough blood flow to the muscle with the consequent
supply of oxygen needed, so the heart understands that the muscles being exercised need to receive
more oxygen and that is why it tries to generate adaptations to try to supply more oxygen.
The way the heart tries to make up for this lack of oxygen in the areas we’re exercising is by
increasing cardiac output and increasing the arterial oxygen content. To do this, what it does is to
increase the mass transport of hemoglobin that we have in the blood.
Since hemoglobin is responsible for transporting oxygen to the organs and tissues of body, what
happens is that hemoglobin is increased in an attempt to increase the arrival of oxygen to the muscle.
The adaptations at the cardiovascular level, and the adaptations at the hematological level
haven’t yet been 100% demonstrated, but all the preliminary studies that we have so far, such as the
study by Pignanelli et al in 2021 [111], point to the fact that BFR training also produces cardiovascular
adaptations at the hematological level and the vascular system level and improves the blood vessels
capacity.
Hypertrophy of type I fibers
Another specific adaptation that occurs with hypertrophy training with light loads and applying
BFR is the greater increase in the slow fibers size (type I red fibers).
Hypertrophy of slow twitch red fibers is something that doesn’t usually occur with strength training
or if it does occur it’s to a lesser extent.
However, training with light loads and BFRS has been shown to generate greater increases in
type I fiber size.
This has been demonstrated in many studies such as those by Bjørnsen et al. in 2018, 2019 and
the latest and final one in May 2021, as well as in the trial by Jakobsgaard et al. in 2018 [80][81][82]
[112].
Training with light loads but taken to muscle failure and training with BFR also very close to
muscle failure have been found to produce increases in muscle fiber size [99]. This suggests that both
forms of light-load training (both with BFR and without BFR) promote hypertrophy by similar
mechanisms.
However, only BFR training with light loads has been shown to be as effective in terms of
hypertrophy and strength gains as conventional training with much higher loads.
This provides a possible specific answer on the type of fiber that is worked depending on the
load, although the increase of type I fibers has only been seen in BFR training with low loads.
It could be a very good idea to include BFR training sessions in our training routine in order to
promote hypertrophy of type I fibers and thus achieve greater size gains in the medium and long term,
as suggested by Hanke et al., 2020 and Bjørnsen et al., 2021 [6][112].
Undoubtedly, the fact that BFR can generate greater hypertrophy in type I fibers is interesting and
much more research is needed. One of the most striking early studies in this field was by BjØrnsen et
al., 2019 [80].
In this study, the sample was seventeen national level powerlifters and with just the application of
BFR during a few sets of front squats for only two weeks significant gains in type I fibers were
observed.
It’s quite surprising because with only two weeks of BFR training and in subjects of an advanced
level, it was not expected to obtain such evident changes in terms of hypertrophy of type I fibers.
The researcher Chris Beardsley who’s a reference in the field of hypertrophy echoed on
Instagram the first study of BjØrnsen and collaborators, and when asked about the amazing results of
that study in his blog, he said he could not find any explanation for that result.
Until relatively recently, researchers like Chris Beardsley and Brad Schoenfeld in their books and
papers, barely made references to BFR training and only mentioned it in passing for rehabilitation and
therapeutic purposes, but never as a tool to optimize hypertrophy. The truth is that it was already
known (or at least suspected) that BFR training plays a very important role in the hypertrophy of type I
fibers.
In May 2021, BjØrnsen's team published a new study in which it was once again demonstrated,
and this time very clearly, that training with BFR and light loads not only achieves the same
hypertrophy adaptations as training with high loads, but also produces more hypertrophy of type I
fibers [112].
In light of this new study
from Bjørnsen's team, Brad Schoenfeld made a post on his Instagram inviting athletes training with
hypertrophy goals to add a portion of BFR to their workouts, as evidence shows that it contributes
significantly to hypertrophy of type I fibers, and increasing the size of these fibers will contribute to an
increase in overall muscle size.
It seems that with this we have yet another reason why we should use BFR training when the
goal is muscle mass gains. And this is the recommendation of Brad Schoenfeld who’s undoubtedly
one of the greatest researchers and experts in the field of hypertrophy.
The crossover effect with BFR
The crossover effect consists of provoking bilateral adaptive responses by training strength in a
single hemi body. This basically means that you can unilaterally train a limb or muscle such as the
right pectoral and thereby obtain strength adaptations in the limb or muscle that you don’t train, in this
case the left pectoral.
What this effect produces is that part of increase in strength that you gain in the unilaterally
trained limb or muscle will also manifest itself in its untrained contralateral counterpart.
This effect has been known since 1894 and according to the meta-analysis of Munn, Herbert and
Gandevia in 2004 [113], in which 16 studies were collected where this effect was studied in a range of
training sessions between 15 and 48 sessions. It was concluded that the part that was not trained
gained approximately half the strength was trained part or limb that.
The reason for this phenomenon is not yet understood, but there are two main hypotheses:
1.
The first hypothesis suggests that unilateral strength training activates neural circuits that
also modify the efficiency of motor pathways projecting to the untrained and opposite limb.
These modifications would lead to an increased ability to exert force in the untrained
muscles, thus resulting in increased strength in the untrained limb.
2.
The second hypothesis suggests that unilateral strength training produces adaptations in
motor areas that are primarily involved in controlling the movements of the trained limb, but
somehow the opposite, untrained limb can access these modified neural circuits and benefit
from some adaptations that have been generated in them.
With blood flow restriction training this crossover effect also occurs, but, for some unknown
reason, it only occurs when the training is eccentric or contains both phases or both types of
contraction. The concentric phase and the eccentric phase.
When BFR training is only concentric and the eccentric phase is eliminated, the crossover effect
in which the untrained part or limb gains strength doesn’t occur. This was verified by Hill and
collaborators in a recent study [114].
In principle, it doesn’t make much sense for someone to train strength only with the concentric
phase, the normal thing would be to complete both phases, but in the search to understand the
mechanisms by which the cross-transfer occurs, it does make sense to investigate the two types of
contraction separately and that is why these types of trials are performed, since the mechanisms
involved in the crossover effect are still unknown and need to be investigated further.
Previously, Maradane et al. in 2008 [27], had already found that the crossover effect phenomenon
was also manifested with BFR training. But Hill's team in 2020 wanted to go a step further and test
whether the type of contraction also affected the crossover effect and indeed it did. In their trial it could
be seen that when only concentric contractions are involved in BFR training, the crossover effect
doesn’t occur.
In 2019 Ampomah et al [115], wanted to test if somehow cross-transfer could occur in the trunk
extensor muscles by applying BFR in the lower and upper extremities (in legs and arms).
The exercises performed in the intervention were leg extensions, calf raises and elbow flexion.
The idea was to see if some type of cross-transfer could be given to strengthen mainly the square
lumbar, since the study subjects suffered from low back pain (unspecified) and the idea was to
strengthen the area.
Results of study were that there was no transfer to the trunk extensor muscles when BFR was
applied to the legs and arms.
As expected, it appears that this cross-transfer phenomenon occurs only in the contralateral
untrained homologous muscle.
Even so, the trial by Ampomah and colleagues [115] made a lot of sense, since, as we will see in
the following chapter, improvements in hypertrophy and strength were seen in muscles where BFR
was not directly applied.
That is, improvements were seen in groups such as the shoulders, pectorals or back, when these
groups were trained, but BFR was applied to the legs or arms. This has been seen in trials such as
Yasuda et al., 2010 and Dankel et al., 2016 [24][116].
So it might make sense to suspect that perhaps these improvements might be due to there being
some degree of cross-transfer, even if it was not the contralateral homolog, hence the investigation by
Ampomah et al. to see if it was somehow possible to strengthen the spinal erectors using BFR on
arms and legs.
Musculature effects without BFR
BFR training has proven to be effective not only in the extremities muscles where blood flow
restriction is applied, but also in other muscle groups such as the shoulders, pectorals or dorsal.
Hence, the application of BFR bands when performing multi-joint exercises with the aim of
developing strength and hypertrophy in the chest, shoulders or back is not only possible, but
interesting and can be beneficial.
The most usual when we think of BFRT, would be to apply BFR on the extremities whose
musculature we want to work, but this is not the only way in which we can use BFR training.
Regarding the use of BFR bands in multi-joint exercises, the first thing that comes to mind is the
use on the lower extremities to work the legs, but we probably wouldn't think of using the bands to
work, for example, the back or chest.
However, it turns out that occlusion bands can be used on the upper extremities for the purpose
of working the back or chest muscles.
It has been found that when back or chest exercises are performed with BFR applied to the
extremities (legs or arms), there is greater muscles activation involved compared to when BFR is not
used.
The first to demonstrate that using occlusion bands on the extremities resulted in greater
increases in EMG activity and improvements in muscles that didn’t have occlusion bands applied was
Yasuda et al. in 2010 [24].
In Yasuda's study, BFR was applied to the arms to work the bench press and it was observed that
the group that applied BFR improved strength and muscle mass significantly over the group that didn’t
apply BFR.
Specifically, the results in the Yasuda trial were bench press strength gains of 6% in the BFR
group versus gains of 2% in the non-BFR group.
In order to be able to record possible increases in hypertrophy, the Yasuda study measured the
thickness of the triceps brachii and also the pectoralis major. The result was an 8% increase in the
pectoralis major in the BFR group compared to only 1% in the non-BFR group, while in the triceps
brachii there was a 16% increase in the BFR group compared to a 2% increase in the non- BFR
group.
The results of trial by Yasuda et al [24] suggest that BFR training significantly increases the upper
arm (triceps) and chest muscles, as well as producing greater strength gains.
These findings of Yasuda et al. were corroborated six years later by Dankel et al. [116], in a study
in which they found that muscle size and strength could be increased in several upper body muscle
groups, thus proving that the positive effects of BFR training were not limited to the limbs alone.
In the 2016 Dankel et al. trial [116], they found that groups close to the restrictive stimulus, such
as the chest, shoulders, or back, also benefited from blood flow restriction in the upper extremities.
An interesting finding from the Dankel et al. study is that they found that hypertrophy and strength
increased in a very similar manner at both higher and lower than usual pressure levels. So, we know
that the range in pressure levels that we can use to obtain optimal BFR is very wide and doesn’t need
to be exact or overly precise by any stretch imagination. We will discuss this in depth in a separate
chapter.
Although it’s not yet understood exactly by what mechanisms hypertrophy and strength
adaptations are generated in muscles that don’t have BFR directly applied, one of the hypothetical
ways that is discussed would be because the system detects a greater accumulation of metabolites in
the auxiliary muscles (in this case the arms), and to compensate for this it activates much more the
main group that we are stimulating in the multi-joint exercise.
Therefore, in addition to the advantages in terms of testosterone, growth hormone and IGF-1
production and many others that are obtained with BFR training. With respect to training without BFR
and all the specific adaptations that are produced and of which we have spoken in this chapter, we
must also add that with BFRT a greater target muscle activation is achieved regardless of whether it’s
an extremity or not, and that this can benefit from greater activation that finally leads to greater
adaptations of hypertrophy and strength.
THE SECURITY OF BFR TRAINING
Data and studies on the security of BFRT
To understand the risks and safety of BFRT, the best we can do is to review all the available
evidence assessing the safety and risks of BFR training.
The first large-scale study on safety with BFRT that we can look at is the 2006 study by Nakajima
et al [110]. In this study, 12,642 participants were surveyed to obtain reliable data on the actual safety
of BFR training.
The 12,642 respondents in Nakajima's study came from 105 facilities in Japan where the
KAATSU method was regularly applied.
The sample was 45.4% male and 54.6% female. There were people of all ages, ranging from
young people under 20 years old to those over 80 years old. The population sample of Nakajima's
study is very varied because the use of KAATSU in Japan is very broad, both to strengthen the
muscles of athletes and to promote health in the elderly.
One point to keep in mind is that among the sample there were also people with different types of
physical conditions, such as obesity, heart disease, neuromuscular diseases, diabetes, hypertension,
respiratory diseases, among others.
Kaatsu method use in most of the facilities were sessions ranging from 5 to 30 minutes, and
these sessions were held between one to three times a week
Among the 12,600 people, there was one case of rhabdomyolysis. Rhabdomyolysis is a disease
caused by muscle necrosis that results in the release into the bloodstream of various substances that
are normally found inside the cells that make up muscle tissue, such as creatine phosphokinase
(CPK) and myoglobin.
In addition to the case of rhabdomyolysis, there was also a case of pulmonary embolism.
Pulmonary embolism is a blockage in one artery in the lungs. In most cases, pulmonary embolism is
caused by blood clots traveling to the lungs from deep veins in the legs.
There were two cases of cardiac ischemic. cardiac ischemic occurs when the arteries that
supply blood to the heart muscle become partially or completely blocked, so that blood flow doesn’t
reach it.
And seven cases of venous thrombosis were found. Deep vein thrombosis (DVT) is a condition
that occurs when a blood clot forms in a deep vein. These clots usually form in the lower legs, thighs
or pelvis, but can also appear in the arms.
In view of the data available to us, the incidences collected in the intervention of Nakajima et al.,
2006 [110], aren’t higher than the incidences occurring with training without blood flow restriction.
The conclusions of Nakajima's study are that KAATSU or BFRT training can be used to train both
athletes and healthy people, as well as people with various physical conditions or even pathologies
(obesity, diabetes, hypertension, among others).
In this table we can see complete survey results by Nakajima et al., 2006 [110].
Side effects
and type of
installation in
Total
Hospitals
which they
Chiropractors
and osteopaths
Acupuncturists
and
moxacauterizers
Rehabilitation
centers
Gyms
Others
2
occurred
Subcutaneous
1651
156
300
86
2
1105
Numbness
164
6
67
42
1
48
Cerebral anemia
35
10
3
21
-
-
1
Cold sensation
16
2
10
1
-
3
-
7
1
3
3
-
-
-
Pain
5
1
4
-
-
-
-
Itching
3
-
-
-
-
3
-
-
-
-
-
-
-
Disease
2
-
2
-
-
-
-
Feeling sick
2
-
1
-
-
1
-
2
-
1
-
-
-
1
2
-
1
1
-
-
-
2
2
-
-
-
-
-
1
-
1
-
-
-
-
Rhabdomyolysis
1
-
1
-
-
-
-
Palpitations
1
-
1
-
-
-
-
Nosebleeds
1
-
1
-
-
-
-
-
-
-
-
-
-
-
Retinopathy
1
-
1
-
-
-
-
Fainting
1
-
1
-
-
-
-
1
-
1
-
-
-
-
Hypoglycemia
1
1
-
-
-
-
-
Edema
1
1
-
-
-
-
-
hemorrhages
Venous
thrombus
Myocardial
ischemia
Increased blood
pressure
Physical
tiredness
Dizziness
Pulmonary
embolism
Deterioration in
diabetics
Cerebral
infarction
Brushes
1
1
-
-
-
-
-
As can be seen in the table, no negative effects on vascular function or blood coagulation are
usually reported.
No alterations in the peripheral nerves function are seen either. It was feared that the peripheral
nerves could be damaged due to the pressure of the occlusion bands, especially when they are too
narrow, but as seen in this multitudinous study, this is not something that is usually reported, since
when occlusion bands are used correctly, in no case is pressure applied high enough to produce
damage at the nerve level.
We’re talking about pressures between 6 over 10 and 7 over 10 subjectively, where 10 would be
total arteries occlusion. And always remember that at any sign of pain or discomfort it’s advisable to
loosen the bands pressure, so that considering the basic recommendations for use would be very
complicated that the bands pressure can cause damage to the superficial nerves.
Research and studies on BFRT security
To continue to assess the safety of BFR training, we can also look at the 2011 intervention by
Clark et al [117]. In Clark's study, both inflammation markers and coagulation markers were measured,
and it was found that there were no alterations in these markers, nor were there alterations in vascular
function or alterations in any peripheral nerve.
It’s important to emphasize that unlike the Nakajima study where the sample included people with
all types of diseases and pathologies, the intervention by Clark and collaborators was carried out in
healthy people, and it was seen that at least in the short term (the study lasted 4 weeks) no significant
alterations could be observed.
Cardiovascular safety, muscle damage and oxidative stress
With the aim of investigating the safety of BFRT but focusing on the cardiovascular system
(central and peripheral), muscle damage, oxidative stress and nerve conduction responses that
occurred with BFR training we have the research of Loenneke et al. 2011 [118].
In the study by Loenneke et al. 2011 [118] it was concluded that the two groups of subjects
responded equally, and the markers didn’t differ between the BFR group and the non-BFR group.
In any case, we still don’t know exactly the effects that BFRT can have when applied chronically,
at least in the scientific literature, empirically there are many people and athletes applying BFRT
without reporting more problems or incidences than those that can also be reported with training
without BFR.
Cardiovascular risk in population with risk factors
Despite all the benefits that can be obtained with BFR training, it has been seen that there is
some risk in populations with some type of cardiovascular risk such as the elderly or people who have
some pathology or problem at the cardiovascular level.
In this sense, the 2016 study by Barbosa et al [119], seriously questions the safety of BFR training
when it comes to subjects with some type of cardiovascular risk, since in Barbosa's study [119] it was
concluded that BFRT could provoke abnormal cardiovascular responses as a result of increased
metaboreflex activation.
Metaboreflex is an effect of respiratory muscle fatigue that limits performance due to the
accumulation of metabolites such as lactate which, faced with the impossibility of sufficient clearance
due to intense muscle demand, promotes peripheral vasoconstriction via the sympathetic nervous
system. More research is really needed in this regard, but hypothetically this is what would happen
according to Barbosa et al., 2016 [119]. So, in people with some sort of cardiovascular or blood
pressure problem BFRT may not be entirely safe.
It’s entirely plausible that with BFRT there is a slight increase in blood pressure, since the heart
understands that there is a lack of oxygen in the muscle that is being trained, in addition, there is a
need to release certain toxic metabolites that are being generated in the musculature, to all this must
be added the need to send nutrients to generate energy. Therefore, to carry out these functions, the
heart rate increases, the systolic pressure increases and the cardiac output increases, which in turn
increases the blood pressure.
In people with no cardiovascular risk, these small alterations in blood pressure and heart rate
would not be a problem, but in the at-risk population they could be dangerous.
For this reason, there is still some controversy as to whether the BFRT can be applied in the
clinical population with cardiovascular pathologies. For the moment, the most sensible thing to do is to
advise against its use in subjects with any cardiovascular pathology, since in people with some type of
cardiovascular pathology, BFRT would not be risk-free.
As a general rule, it has been seen that when using low loads with BFR, the increases in heart
rate, systolic blood pressure (SBP) and diastolic blood pressure are similar or even lower to the
increases that occur when training with high loads and without BFR (Brand-ner et al., 2014 ; Mouser
et al., 2018) [120][121].
In fact, the team of Pinto et al. in 2018 [122] investigated the cardiovascular and metabolic
response to BFR training of hypertensive women. The trial employed BFRT with low load versus
traditional strength exercise with high loads and demonstrated that BFRT and low loads didn’t induce
an exaggerated or greater cardiovascular or metabolic response compared to resistance exercise
without BFR and higher loads.
In addition, studies by Kambič et al. (2019, 2021) [123][124] reported that BFR training in patients
with coronary artery disease (CAD) is safe and was associated with significant improvements in
muscle strength and muscle function. It was also observed that after 8 weeks of BFR strength training
significantly reduced systolic and diastolic blood pressure in patients with coronary artery disease
(CAD) without producing changes in natriuretic hormone, fibrinogen, or D-dimer values.
However, when BFR training is performed with loads of more than 50% of 1RM, these increases
in heart rate and blood pressure may be more noticeable. I have been able to verify how the cardiac
output and heart rate rise much more with BFR training than with conventional training. Of course, I
am talking about advanced training in which BFR was applied with loads of 60% of 1RM or more.
If you have a device that measures heart rate you can check to what extent the BFRT influences
(or not) your heart rate.
RISKS AND CONTRAINDICATIONS OF TRAINING WITH BFR
How do you know the risk of BFR training?
According to the British Olympic Medical Institute [125] the risk that may be involved in training
with blood flow restriction would be divided into 3 categories, low risk, moderate risk, and high risk.
In this table you can see the pathologies or circumstances that entail risks and the degree of risk
of each one.
*** High Risk
Intrinsic risk
factors
***Blood disordered
coagulation
*** Deep vein thrombosis
***Pulmonary embolism
** Medium Risk
Extrinsic risk
factors
* Low risk
Variables to
monitor
**Electric shock training
Volume and load training
**No history of strength training
Delayed muscle soreness (stiffness)
**After traveling for more than 4 hours by
airplane
Cudden increase of pain
***Vascular trauma
*Use of sleeves longer than 10cm
Vasovagal symptoms
***Traumatic nerve injury
* Use of pressures of more 150mmHg
Blood pressure
***Hemorrhagic stroke
Urine color other than dark
(rhabdomyolysis)
**Diabetes
**Hypertension
**Smokers
**Spinal cord injury
**Any amputation
**Taking oral contraceptives
In the table we can see that within what would be high risk we would have all the alterations and
pathologies that have to do with the cardiovascular level.
Cardiovascular pathologies refer to any type of cardiovascular problem that the person may have
had, such as, for example, a venous thrombus, some type of blood clotting disorder, varicose veins,
pulmonary embolism, cerebral infarction, vascular trauma, among others.
A person who has suffered from any of these ailments would be at high risk if he/she wanted to
perform BFR training, therefore, under no circumstances should he/she use the BFRT.
Within the category of people who would be at moderate risk with BFR training, would be
smokers, people with diabetes, pregnant women, hypertension, people with some type of spinal cord
injury, people with one or more amputated limbs, women taking oral contraceptive medication, in
circumstances of high ambient heat.
Also in the moderate risk category would be people who train with BFR after a long plane ride, as
well as people who have no previous experience with weight training.
That is, someone who has no prior experience with strength training should not begin strength
training directly with BFR, unless under the supervision of a professional or under the guidance of a
strength training professional.
These are some examples of people who would fall into the moderate risk category with BFR
training.
And finally, would fall into the low-risk category all persons who don’t present any problems or
pathologies mentioned above, and who use BFR training intermittently and for a limited time, and with
a maximum pressure of 150mmHg and occlusion bands of a maximum thickness of 10cm.
The evidence currently available to us cannot assure that using blood flow restriction training is
completely risk-free. From the experience of many athletes and the conclusions of some studies it
doesn’t appear that there are more risks with BFR than without BFR [110]. However, it must be
considered that we don’t have medium or long-term studies, hence the general recommendations are
to use BFR training in certain micro cycles, mesocycles, or intermittently.
Empirically the BFRT is used for long periods of time or continuously without observing harmful or
negative effects, I have 2 years of continuous use, but based on current recommendations, the most
sensible is to use it for relatively short periods of no more than 8 weeks, which is usually the duration
of the interventions that are performed, and always adding the BFR to our training in a very
progressive way.
Variables that must be monitored to minimize the risks
Some of the variables that we must consider to minimize the risks would be the training load per
session, the intensity, and the total volume.
As well as the sensations we have during the training, such as, for example, sensations of pain,
numbness, itching, among others. Any symptoms of this type should loosen the device we use for
BFR or directly remove it.
We should also be alert to any vasovagal symptoms such as dizziness, palpitations, pallor,
nausea or vomiting. At the slightest symptom of this type, training should be stopped, and the
occlusion bands should be removed.
Excessive delayed muscle soreness (stiffness) can also be a clear symptom that we’re
overdoing it with the BFRT and we should reduce the volume or intensity of this.
Blood pressure is another variable that could be monitored. To observe alterations in this aspect
it would be necessary to control blood pressure before, during and after training.
Monitoring and controlling blood pressure and observing to what extent it could affect the BFRT in
relation to training without BFR on an individual basis would be interesting to assess the risks,
especially in people at high or moderate risk. But it may also be interesting to know this data in people
at low risk, precisely to be able to verify that the risk is still low and that there is not too great a
variation.
Another important point would be to observe the urine color and check that it doesn’t darken to
detect possible rhabdomyolysis caused by BFRT.
It would be strange and unusual for the urine color to change due to rhabdomyolysis, but it’s still a
possibility that could happen with BFRT and very demanding workouts with excessive muscle
damage.
Rhabdomyolysis is a disease caused by muscle necrosis that results in the release into the
bloodstream of various substances that under normal conditions are found inside the cells that make
up muscle tissue. Among these substances that are released into the bloodstream are the enzyme
creatine phosphokinase (CPK) and the protein myoglobin. Both substances can be detected in a
blood test by asking for markers such as creatine phosphokinase (CPK) and myoglobin. The amount
found in the blood will give us information about the amount of muscle damage we’re generating in
training.
In the case of athletes who train at a high intensity, it would be a good idea to monitor CPK and
myoglobin levels to check that these markers aren’t too high, and if they are too high to consider
reducing the intensity of training.
In any case, it must be taken into account that the level of CPK alterations has a very individual
response in each subject, as seen in the study by Wernbom et al. 2020 [126] [127], where applying
the same training and the same pressure the individual response to muscle damage was very different
between individuals.
In this image from the
Wernbom et al. 2020 trial [126] we can see how at the same workload two intervention subjects reach
excessively elevated CPK levels, with the maximum peak at 4 days. However, the other subjects
maintain low CPK levels.
It should be considered that all the subjects in the study performed the same exercises and with
the same pressure, so we can conclude that the individual response to muscle damage with BFR
training is highly variable.
Undoubtedly, trying to progress as progressively as possible and allowing correct adaptation to
BFR training will be the best strategy to avoid such drastic alterations.
Rhabdomyolysis is a possible negative effect of BFR training. However, following the guidelines
and recommendations seen in the studies, as we will see in the chapter on how to apply BFRT, it
should not occur, although it’s true that in the literature we can find quite a few cases.
In this regard, we have a trial by Patterson and Brandner from 2018 [128]. In that study they
surveyed 250 subjects from 20 different countries who used BFR training for different purposes, such
as gaining muscle mass or reducing atrophy, and found that 3% of the subjects reported
rhabdomyolysis as one side effects.
Survey results of Patterson et al [128].
As can be seen in the graph, 3% of the respondents reported rhabdomyolysis, 8% cold sensation,
13% bruising, 15% fainting or dizziness, 18% numbness and 39% delayed muscle pain (stiffness).
Delayed muscle pain is undoubtedly the most common side effect. This occurs especially when
we’re still adapting to BFR training, and we exceed the intensity or volume of training. It should be
considered that slight stiffness is normal, but persistent and excessively painful stiffness should be
avoided, and measures should be taken so that it doesn’t happen again, since it’s undoubtedly a clear
symptom that we’re overdoing it and it will not make us improve, but rather the opposite.
In the end, delayed muscle soreness is quite common and tends to happen especially in the first
BFR training session. However, we should pay special attention to the rest unwanted effects, and if we
notice any symptoms of discomfort or discomfort, we should loosen the bands. It’s a matter of using
common sense and handling the BFRT correctly, as well as being attentive to sensations and avoiding
discomfort or pain with the use of BFR. The BFRT should in no case cause discomfort or pain, and a
higher pressure than recommended is not going to bring greater benefits.
In any case, more studies will be necessary, especially in the longer term, to be able to correctly
delimit the risks of training with BFR.
Despite the possible contraindications, the fact is that serious problems such as pulmonary
embolism aren’t at all common.
In fact, in 2007 Nakajima et al [129] conducted a trial to observe how BFR training affected
hemostasis, and concluded that with Kaatsu training in healthy subjects, potentially favorable changes
in fibrinolytic factors occur, which precisely helps in the disintegration of clots.
In addition, Nakajima et al.,2007 also pointed out as early as 2007 that there were more than
200,000 people worldwide training with BFR and no case of pulmonary embolism had yet been
recorded.
Interestingly, in Nakajima's study there was one subject who was feared to suffer a possible
pulmonary embolism, but in the end, it turned out to be an acute bronchitis, which didn’t require
hospital admission.
In any case, prudence and common sense should be paramount when using blood flow restriction
training.
And one thing I never tire of stressing is that one must keep in mind that the long-term effects of
this type of training are still unknown, so some caution must be maintained after all.
How to assess the risks of BFR training
A simple way to determine who can and who under no circumstances should train with BFR
would be based on the indications given by Thomas Bandholm [130].
In this risk scale made by Thomas Bandholm based on Nakajima's recommendations [131], when
4 points are exceeded or equal, blood flow restriction training should not be used.
History of deep vein thrombosis
Acute disease or fever
Very high blood pressure, more than 180/100 mmHg
Early postoperative period
Arrhythmias or myocardial ischemia
Pregnancy
Varicose veins
Very long period of inactivity
Atrial fibrillation or heart failure
High blood pressure between 160-179/95-99 mmHg
Over 60 years old
body mass index over 30Kg/m²
Hyperlipidemia
Between 40-58 years old
Woman
Body mass index between 25-30Kg/m²
5 points
4 points
3 points
2 points
1 point
Thus, we see that those who have 4 or more points on the Thomas Bandholm table should not
train with BFR. Therefore, pregnant women, people with a history of deep vein thrombosis, acute
illness or fever, blood pressure above 180/100 millimeters of mercury (mmHg), people in postoperative periods, and people suffering from arrhythmias or coronary ischemia would not be able to
train with BFR.
At a somewhat lower risk level and with a score of 3, would be people with blood pressure
between 160-179 systolic pressure and between 95-99 millimeters of mercury diastolic pressure,
people with atrial fibrillation or some type of heart failure, people with varicose veins or who have been
too long without any type of physical activity.
With a score of 2 would be people over 60 years of age, people with a Body Mass Index above 30
kg/m2, hyperlipidemia (excess cholesterol or triglycerides in the blood), and women who are being
treated with estrogen therapy.
A score of 1 would be received by subjects between 40 and 58 years of age, women, and people
with a Body Mass Index between 25-30kg/m2.
It should be remembered that each condition has a score, and this is summed, being that when
the total score is 4 or higher the BFRT would be totally contraindicated.
Thomas Bandholm [130] also proposes that this survey should be carried out where some
questions are asked to the patient or client. Questions such as, if in the family there is a history of
coagulation disorders, if you have hypertension or systolic pressure above 140 millimeters of mercury,
if you have had any type of venous thrombus or pulmonary embolism or if you have had any type of
stroke.
If the answer to any questions is YES, under no circumstances should you train with blood flow
restriction.
RISK
MAGNITUDE
MEDICAL HISTORY
AND LIFESTYLE
Do you have a family history of clotting disorders?
(hemophilia, high platelets)
Do you have systolic blood pressure above 140
ABSOLUTE mmHg?
RISK
Do you have a history of deep vein thrombosis or
pulmonary embolism?
Have you ever suffered a hemorrhagic or
thrombotic stroke?
ANSWER
YES
NO
YES
NO
YES
NO
YES
NO
DECISION
Consult
doctor
Continue
Stop
Continue
Stop
Continue
Stop
Continue
Among the tips provided by Thomas to increase safety in BFRT include the following
recommendations.
Use correct technique and standardized risk assessment (cuff, pressure, exercise dose/intensity,
DVT history, among others).
Indirect harms results indicate that BFR influences cardiovascular, nerve and muscle function in a
manner comparable to high intensity strength training (level of evidence 5).
Common clinical harms include DOMS, subcutaneous hemorrhage, and numbness (level of
evidence 4 and 5).
Rare (serious) clinical harms include rhabdomyolysis and venous thrombosis (level of evidence 4
and 5).
It should be noted that, although there is increasing research regarding BFRT, it’s likely that some
of the potential harms it may cause aren’t yet reported in the scientific literature.
These recommendations by Thomas Bandholm [130] are only the most serious issues to be
considered. But really Bandholm's recommendations are only a small part of all the recommendations
given by Kacin et al. (2015) [132]. The full list of recommendations given by Kacin's team can be seen
in the following table.
BFR training for people suffering from any type of pathology
Recommendations by Kacin et al. (2015) [132] to assess possible risks in people with some type
of pathology and the risk magnitude.
RISK
MAGNITUDE
ABSOLUTE RISK
MEDICAL HISTORY
AND LIFESTYLE
Do you Have a family history of clotting disorders? (hemophilia,
high platelets)
ANSWER
DECISION
YES
Consult doctor
NO
Continue
Do you have systolic blood pressure above 140mmHg?
Do you have a history of deep vein thrombosis or pulmonary
embolism?
Have you ever suffered a hemorrhagic or thrombotic stroke?
Are you a smoker?
Are you taking any type of medication or the contraceptive pill?
Do you have a history of vein or artery injury?
Do you have a history of nerve injuries? (inc. back or cervical)
Are you diabetic?
RELATIVE RISK
Any of your parents or siblings diabetic?
Do you have systolic blood pressure between 120-140mmHg?
¿Tiene algún dolor en la ingle o pantorrilla no diagnosticado?
Do you have any undiagnosed groin or calf pain?
Have you had any surgery in the last 4 weeks?
Do you have any other medical conditions or synovitis?
YES
Stop
NO
Continue
YES
Parar
NO
Continue
YES
Stop
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
YES
Consult doctor
NO
Continue
When elucidating whether BFR training is safe in people with any type of pathology, in addition to
reviewing the recommendations of Kacin et al [132], we can follow the approach proposed by Scott
and colleagues [133] in their article.
The recommendations of Scott and his team basically summarize that if you have any type of
pathology that may pose a contraindication for BFRT, you should consult with a medical specialist to
assess your case and decide whether you can train with BFR.
That is also my recommendation, in case you have any type of pathology that may be
incompatible with BFR training you should consult with a specialist who will evaluate your case and
decide whether you can use BFR in your workouts.
Scott and Loenneke's proposal [133] on the steps to follow to implement the BFRT (or not) in
people with some type of pathology.
Basically, what the team of Scott and Loenneke [133] propose in order to ensure the safety of
BFRT for the purpose of gaining muscle mass, is that in case you have any kind of contraindication to
use BFRT, what you should do is to consult with a physician so that he/she can make a more accurate
assessment of your particular case.
In the case that the person has no contraindications, or the doctor has approved the BFR training,
the next question to ask is whether the person can move. If the person is not mobile, BFR can be
applied lightly to the extremities in order to reduce muscle atrophy, even in the absence of physical
exercise [38].
In the case of mobility, we ask ourselves the following question: can it tolerate loads between 2040% of 1RM?
In case the answer is negative, and the patient cannot tolerate loads of 20-40% of 1RM, BFR can
be used very moderately either during a short cycling or jogging session.
In the case that the person can tolerate loads between 20-40% of 1RM, he/she can use the BFR
with submaximal loads and we could ask the following question: can he/she tolerate high or maximal
loads?
If the answer is no, then you can use the BFRT with submaximal loads, and if the answer is yes,
you can combine training with high loads without BFR with training with submaximal loads with BFR.
Which would probably be optimal for optimizing strength and hypertrophy gains.
The ankle-brachial index
In case you have doubts about whether you have any type of peripheral arterial disease (PAD) it
would be best to perform the ankle-brachial index test. In fact, this test is usually performed on all
participants in trials using BFR training and is grounds for exclusion if the subject shows signs of PAD.
The ankle-brachial index (ABI) is a parameter that shows the ratio between the systolic blood
pressure of the upper extremity and the lower extremity.
It’s a (non-invasive) test in which a device is used to measure blood pressure and take blood
pressure measurements at the upper arm and ankle. The equipment used can be manual or digital
with automatic electronic calculation of blood pressure.
Normally, it’s performed manually because digital devices usually cost several thousand euros
while to perform the test manually all that is needed is a portable continuous doppler with a 5-10MHz
probe, a sphygmomanometer (cuff), and an ultrasound-conducting gel.
Although it’s a simple parameter to calculate, one of the existing limitations for its use is the need
for specific material and trained and experienced personnel to obtain reliable measurements.
Therefore, in case you want to perform this test, you should go to an experienced professional.
The good thing about this test is that it detects a possible PAD in early stages, which would be
useful to be aware of whether we run any kind of risk when using BFR in our training.
Possible results of the ankle-brachial index test
ITB
result
Interpretation
Arterial calcifications (stiff arteries, not compressed so the test isn't applicable),
especially in diabetic arteriopathy.
1-1.30
Normal
0.90-1
Minimal or mild disease (indicates arteriosclerosis)
0.50Mild-moderate (range of claudication)
>1.30
0.90
0.300.50
<0.30
Severe disease (pain at rest)
Critical disease (pain at rest, gangrene)
This test is highly recommended to rule out some type of peripheral arterial disease (PAD) in case
we want to use BFR in our strength training.
DEVICES FOR BFR TRAINING
In this chapter we are going to see the different devices that are normally used for BFR training,
and which of these devices would be the most recommendable for their safety, comfort, value for
money, etc.
We can divide blood flow restriction devices into two main groups:
traditional devices (mainly used in laboratories),
and practical devices (used in gyms).
Within the traditional BFR devices, which are those commonly used in studies and laboratories,
we would have the original KAATSU-Master and Kaatsu Mini, the Delfi customized tourniquet system
(Delfi Medical Innovations System), and the Hokanson rapid cuff inflation system. (Hokanson, Inc.,
Bellevue).
The KAATSU, Delfi, and Hokanson systems are electronically controlled units and are the ones
typically used in controlled clinical studies and settings. Although these devices are very accurate and
are relatively easy to use, they are quite expensive. They are very useful devices in clinical or
laboratory settings.
It must be understood that, although the device may indicate the exact pressure in millimeters of
mercury, a given pressure level will not always produce the same restriction level. The restriction level
depends not only on the pressure but also on other factors such as, for example, the width of the cuff,
the age of the subject, the place where it is placed, the size of the limb and its composition
(fat/muscle), or the systolic blood pressure subject.
That is, a pressure level such as 250 mmHg may produce a very high restriction level for one
person and very little for another, it may be too much pressure and therefore too much flow restriction
with one device with the wide cuff and yet be too little pressure with another.
To suggest a similar pressure approach for all individuals would be something like suggesting that
all people should exercise with the same weight, or run at the same pace, regardless of the specific
characteristics of each individual. It would be something totally absurd.
In fact, the use of fixed pressures that had been done in the past is currently contraindicated
(McEwen et al., 2019) [135]. Since indicating predefined pressures could be pressures higher than the
total occlusive pressure person, which would increase the risks of nerve and ischemic injury.
Another point to keep in mind about traditional electronic and manometer devices is that in a gym
doing strength exercises they are not practical at all, and their use in most cases would make it difficult
to perform exercises that are commonly done in a real training environment.
Inability to use advanced BFR devices in gyms has led to the development of more practical
devices that can be used in a real training environment in a commercial gym.
The most practical way to train with BFR is to use elastic bands or bandages placed around the
limbs. These types of devices are much more affordable and are readily available from online stores
such as amazon.
The use of these elastic bands with adjustable straps is very simple, but they have the problem
that they can be used incorrectly by those who don’t understand how it works and how BFR training
should be performed.
Since these types of devices such as adjustable bands or straps don’t allow precise pressure
control being applied during exercise, extreme care must be taken to ensure that under no
circumstances does total occlusion of blood flow occur.
To provide some useful guidelines, Wilson et al. [26] proposed using a subjective scale of
perceived pressure. This scale ranges from 0 to 10 where 0 is no pressure and 10 is total occlusion of
veins and arteries (something never to be done).
It is about achieving a subjective pressure level of approximately 6 for the arms and up to 7 for
the legs.
Next, let's look at some of the most common devices.
Compression bandages
Compression bandages are often used to compress knees or elbows in sports such as
powerlifting.
They are usually elastic and made of textile materials such as cotton.
They are usually inexpensive, but the precision with which the pressure is controlled leaves a lot
to be desired due to the turns that must be made to place the bandage on the limb, which makes the
control of the final pressure once the bandage is adjusted difficult. In the case of using this type of
bandage, the final pressure that will be obtained is something really complicated to control.
In addition, in case you need to loosen the bandage due to excess pressure or discomfort, you
must remove the bandage completely and then put it back on again, as there is no other way to
regulate the occlusion level.
From my point of view, this type of bandage has many disadvantages and for BFR training I don’t
recommend it at all.
One of the biggest problems that we can find when using this type of bandages is that the
pressure can be excessive, because being normally quite long bandages, they cover a wider area of
the limb and it is difficult to adjust the pressure, since it's necessary to give more than one turn to the
limb and it's easy to overdo the pressure in some of these turns or that the sum turns results in an
excessive pressure. It can also happen that because we are very careful not to exceed the desired
pressure, they are too loose and don’t have a pressure level of at least 50%, which would be the
minimum we should try to achieve.
Finding the ideal pressure, which should be an intensity of 6 out of 10 on the arms (where 10
would be 100% occlusion), and 7 out of 10 on the legs, is usually quite complicated with this type of
bandage. To this must be added the complexity of adjusting the pressure to the two extremities
equally or at least very similarly.
Using an elastic band specifically designed for BFR training to perform the occlusion and having a
strap that you can tighten or loosen will be much simpler and more efficient than using this type of
compression bandage that was not designed for BFR training.
In any case, keep in mind that when we use a device with which we are not able to properly
control the pressure, it will always be better that the device doesn’t over-tighten, and in the case that
it's necessary because the pressure is too low, you could compensate for the lack of pressure with a
slight increase in load, and instead of using a load of, for example, 40% of 1RM, use a load of
approximately 50% or 60% of 1RM.
Using a somewhat higher load when the blood flow restriction is lower than it may be a way to
compensate for the lack of pressure to continue to get improvements from BFR training when the
restriction level is very low.
It appears that BFR training will not only be influenced by the degree of blood flow restriction in
the adaptations achieved, but also by the load to be used.
In the 2016 study by Loenneke et al [136], it was seen that the load was as important as the
occlusion pressure when the objective was to obtain adaptations in terms of hypertrophy and to
generate higher lactate levels and metabolic stress.
Some conclusions we can draw from the Loenneke et al. study is that improvements can be
obtained even with very low levels of occlusion, but for this we must compensate for the low occlusion
level with somewhat higher loads such as 50-60% of 1RM.
In any case, before starting to use higher loads than those recommended (20-40% of 1RM), it's
highly recommended to have enough experience and a high degree of adaptation to BFR training in
order to avoid problems and a high rate of muscle damage.
In any case, not exceeding the occlusion pressure is important to avoid vascular or superficial
nerve damage. So, it's probably best to increase the load slightly before increasing the occlusion
pressure to the point where it becomes uncomfortable or excessive. One thing to be very clear about
is that at no time should the pressure be painful or excessively uncomfortable.
If you are in doubt as to whether the pressure is sufficient, it is always better to go a little too low
with the pressure level exerted by the device than to go too high and have an excessive pressure
level.
In addition, it has been seen that similar results can be obtained with such a wide range of
pressure levels from 40% to 80%. That is, a pressure that on a subjective scale of 1 to 10 is between
4 and 8 will achieve a very similar blood flow restriction level.
That is the conclusion drawn by Crossley et al. in a recent study [137]. So, since safety comes
first, it is always going to be preferable to fall a little short with the pressure level, rather than overdo it
with the pressure and completely occlude blood flow.
Another drawback to keep in mind if we choose to use elastic compression bandages such as
those used for knees or elbows in lifting, is that the surface area they usually cover is quite large.
The larger the surface area, the easier it's to occlude the arteries, and this is not in our interest at
all, since what we are trying to restrict (not completely occlude) is venous return, not the inflow of
oxygenated blood coming through the arteries.
In addition, occluding the arteries would have a greater risk of thrombus and vascular damage, so
we must be careful when using this type of elastic bandage and always avoid excessive pressure,
regardless type of device used.
I really don’t recommend the use of this type of compression bandage at all. I have seen athletes
who use them at certain times, and they can be useful for occasional use, but they are not at all
optimal if the objective is to train with BFR on a regular basis.
I think that, if the idea is to train with BFR in an optimal way, you must use another type of
material more specific for the purpose we are looking for, which is none other than to generate a
restriction of blood flow that we can control and adjust well depending on our goals at all times.
Inflatable compression cuffs (Kaatsu)
Inflatable cuffs have the advantage of allowing you to monitor the actual pressure always exerted.
it's easy, accurate, and simple to measure the pressure at which training is being performed when
using this type of inflatable cuff. For this reason, these devices are the most used in most studies.
The main problem with compression cuffs, or at least one of their drawbacks, is their high price. In
fact, some systems have totally exorbitant prices, the KAATSU Master II equipment has a price that
exceeds 5,000 euros. It is also true that the lower models of the range are at more affordable prices,
although they are still quite high.
I understand that for researchers and elite athletes of the highest level it may make sense to
invest in such equipment, which can always display the pressure being generated in millimeters of
mercury on a monitor or screen.
But for the average or advanced gym user I don't see much sense in this type of device. Not only
because of the price, which is around 400 euros, but also because for the user who trains with the
objective of strength and hypertrophy gains it's not very practical to be aware of the exact pressure or
to have to be adjusting the pressure very often, especially when it is known that there is a pressure
margin of 40% in which the restriction level obtained is very similar.
In any case, if for whatever reason someone prefers a device that can measure the pressure with
a manometer, today there are already many options on the market for equipment that can measure
the pressure exerted by the inflatable cuffs, and some of them are much cheaper.
With a much more affordable price than the official Kaatsu cuffs. We can find on amazon
inflatable cuffs that bring their manometer with which we can see the pressure we are exerting.
In fact, the market for BFR training devices is becoming more and more advanced. Currently
there are devices on the market that are controlled from a mobile application, you select in the
application the pressure you want to use, and the device is responsible for maintaining that pressure
in a stable manner. In addition, the prices that are handled in the current market for these latest
generation devices are already quite affordable.
In any case, before you go ahead and buy one of these devices, read on because we will talk
more in detail about the pressure that the device we use has to exert and whether it's really important
to have total or absolute control over the pressure we are using in our BFR training.
As for the compression cuffs that offer us the possibility of controlling the pressure, we find that
the width they usually have is quite variable. We can find that the width of the legs can range between
6-15cm while the width in the arms is usually between 3-6cm. Keep in mind that the wider the cuff, the
easier it's to occlude the arteries and it's not our goal to occlude but the venous return. In my opinion,
inflatable cuffs with an excessive width of more than 10cm should be automatically discarded.
Example of inflatable cuffs with manometer
Medical tourniquets
The use of a medical tourniquet can be a good option to get started with BFR training.
The main advantage is its price, since for a few euros you can get a pair of medical tourniquets in
any pharmacy, and in case they don’t have them at that moment, you can order or directly buy them
online at amazon.
Medical tourniquet
This type of tourniquet has the particularity that by pressing a button it loosens quickly, which can
be interesting in the case that we want, for example, to remove or loosen the BFR in the breaks
between sets.
From my point of view, removing the BFR between sets may not be optimal, especially when
using loads of 30% of 1RM or less, because removing the device will dissipate some metabolic stress
during the rest period. Although it is true that if the rests are short (30 seconds or less), it doesn’t
seem to affect the adaptations since not much metabolic stress is dissipated.
One of the drawbacks of medical tourniquets is that, due to their size, they can only be applied to
the arms.
But to start experimenting with BFR training by applying it only on the upper extremities to obtain
improvements in the arms, or on other torso groups such as the latissimus dorsi, pectoralis major or
shoulders, medical tourniquets could be a good option to start with, especially because of their low
cost.
Occlusion bands with adjustable strap
This type of bands with a slightly elastic fabric and adjustable strap are without a doubt my
favorite for several reasons.
They are very economically priced, they are easy to put on and take off, once they are on you can
adjust the pressure by tightening or loosening the band, they have been shown in studies to be
perfectly valid and a very accurate pressure can be obtained with them in a totally subjective way
[138][139].
Elastic BFR bands with adjustable strap
In addition, this type of occlusion bands with adjustable strap have been manufactured
exclusively for BFR training and in the pack usually come in two pairs, a pair of bands for the upper
extremities and another pair of bands of a larger size and thickness for the lower extremities.
It is necessary to pay attention to the thickness and that this is different depending on whether the
bands are for the lower or upper extremities, because there are some bands of this type on the market
with an identical thickness in both pairs of bands. And when the upper extremity band has the same
thickness as the lower extremity band, it is too much for the arms and they are not so comfortable.
Another important point, at least for me, is that the length of the upper limb bands is long enough
to fit arms over 50cm, whereas there are no inflatable sleeves in that size, or at least I haven't seen
them anywhere.
Then we have the bonus that these types of bands are a good price. Right now, there is a great
variety of this type of bands on amazon and you can find them in good quality at a low price.
However, I recommend buying the pack that brings the pair for the arms and legs, since the legs
pack is not sold separately, and generally the bands that come only for the arms are made with
materials of a lower quality and with an excessive thickness that makes them uncomfortable when
used on the arms. To be able to train with BFR correctly there is nothing better than to do it with bands
that are manufactured correctly and fulfill their function well.
Considering that inflatable bands have not been found to be superior and yet are much more
expensive, the ones I use and recommend are occlusion bands with an adjustable strap and a certain
degree of elasticity.
The fact that occlusion bands with adjustable straps don’t have a device that indicates the exact
pressure is not a problem at all, since it has been seen in different studies that a person with no
previous experience is able to self-regulate the pressure level subjectively on a scale of 1 to 10 with a
more than acceptable accuracy, as was seen in the Bell et al. trial in 2018 [138][139].
It seems that subjectively without the need for a manometer we are quite accurate with the
pressure level [138], and also keep in mind that there is a pressure range from 40% to 80% with which
a similar blood flow restriction level is obtained, so it's not even necessary to be that precise in getting
the pressure level right.
For that reason, I consider elastic and strap-on blood flow restriction bands to be an inexpensive
and effective option for use in our BFR training sessions. In addition to the fact that it has been shown
that a person is able to self-regulate pressure subjectively using a scale sufficiently accurately of 1 to
10 where the ideal pressure would be 6 [138].
Another point in favor of elastic BFR bands with adjustable strap is that Oliveira et al. in 2020 [32]
demonstrated that there is no difference in adaptations and metabolic responses between the use of
inflatable cuffs with manometer and occlusion bands with adjustable strap. So, for comfort, utility and
price I will stick with good adjustable straps as my favorite device for BFR training.
PRESSURE LEVEL AND HOW TO CALCULATE IT
We know that we have some leeway in the pressure we use to get good results with BFR training.
In the trial by Crossley et al., 2020 [137] it was seen that there was no difference in adaptations
between using an occlusion level ranging from 40% to 80%.
For this reason and others that we will see below, I at least don’t see the need to purchase an
advanced device that comes with a manometer.
If later on they make one that is at a good price and is comfortable, maybe I will try it simply out of
curiosity, but to date I have to say that I don’t know if it will really offer any kind of advantage at least in
comfort or sensations compared to an occlusion band with an adjustable strap, in terms of results we
know that it doesn’t [32][140].
I would have liked to try one to be able to give my opinion from experience, but in the market, I
didn’t find any inflatable device that would fit my arms so the experience I have is with compression
bandages that I don’t recommend at all, and with occlusion bands with adjustable strap, which is the
device I always use.
About different types of devices, we know that there is no difference between using an inflatable
cuff versus a band with an adjustable strap.
So, for comfort, ease of use and price, my choice and recommendation is to use an elastic
occlusion band with an adjustable strap.
In the U.S. some experts recommend inflatable devices with manometer and warn of the dangers
of not having control over the pressure, curiously they have contracts with the companies that
manufacture these devices, or they manufacture them themselves.
It has been seen that these manometer cuffs are not necessary. Firstly, because the pressure can
be checked subjectively with hardly any margin of error and if you overdo it with the pressure, you will
notice it immediately because you will feel discomfort. And secondly, because inflatable cuffs with a
manometer have not been shown to offer any advantage over blood flow restriction bands with an
adjustable strap.
Already in 2013 Loenneke et al [140] measured the efficacy and possible differences in restricting
blood flow with inflatable cuffs versus occlusion bands.
In the Loenneke et al. trial, the thickness of both devices was 5cm and they could find no
difference in the levels of blood flow restriction between the inflatable cuffs and the more conventional
occlusion bands. Authors conclusion in that study [140] is that at equal band thickness and regardless
of the material, there will be no difference in blood flow restriction.
And obviously, since there will be no difference in blood flow restriction, there will be no difference
in hypertrophic response (increases in growth hormone, lactate, IGF-1, etc.).
This is something that was proven 4 years later (in 2020) by Oliveira team et al [32], where they
observed that there were no differences in metabolic and hormonal responses between the use of
inflatable occlusion bands and adjustable occlusion bands.
Therefore, Oliveira's recommendation [32] was that we should opt directly for the use of
adjustable strap-type bands because they are much more economical and just as effective.
A very important fact to bear in mind when applying inflatable blood flow restriction bands with
which the exact pressure can be controlled is that the pressure required by each person is not always
the same and will depend on the size of the limb.
So it's not useful to give guidelines of a fixed pressure level for each limb since the optimal
pressure level will depend on the thickness of the limb and this will be different for each person.
It's quite funny that those who try to sell you that you need to control the pressure and therefore
you need at least a manometer cuffs, give you indications on the pressure you should get in the lower
and upper extremities. However, the pressure needed to achieve a certain occlusion level will be
different depending on the thickness of the limb and can be very different from person to person.
This has been known for some time and was seen in the 2012 study by Loenneke et al [141],
where they found that the larger the circumference of the leg the more pressure was needed to obtain
the same occlusion level.
The relationship of circumference to pressure with which 60% occlusion level was obtained would
be as follows:
Pressure that should be used depending on the perimeter of the thigh.
<45-50 cm
120 mmHg (milimeters of mercury)
51-55 cm
150 mmHg
56-59 cm
180 mmHg
>60cm
210 mmHg
A year later and in another of their research articles, Loenneke's team [142] already give clear
indications and propose to adjust the pressure depending on the circumference of the limb.
As we can see, it must be considered that the larger the size of the limb (in this case the legs),
the more pressure will be necessary to obtain the same restriction level.
This fact that the larger the circumference of the limb the more pressure we must use gives us an
interesting fact that we can take into account when applying pressure, and gives us an idea that in the
lower limbs we have more margin with the pressure since having a larger circumference can tolerate
more pressure, while in the upper extremities we must be more careful with the pressure and not
overdo it, since being normally smaller the arteries circulation can be restricted more easily and we
could damage nerves if we use excessive pressure.
In any case, overdoing it with the pressure level is complicated, since excessive pressure would
be annoying and painful, and the discomfort would be indicating that we are exceeding the pressure,
so at any sign of pain or discomfort we must reduce the pressure.
Another reason for not having to use excessive pressure is that pressure is not linear, i.e., the
more pressure there is not always more restriction of blood flow, there is a margin of 40% of pressure
in which the same restriction level is obtained. So, we can get all the benefits of BFR training without
having to apply excessive and uncomfortable pressure.
This 40% margin in pressure level was verified in the 2020 study by Crossley et al [137]. In that
study, they found that the blood flow restriction level was practically the same at pressures ranging
from 40% to 80%.
Thanks to the 2020 study by Crossley et al [137], we know that it's not necessary to apply too
high pressures to restrict blood flow. So, a lower pressure at which we are more comfortable will be
more appropriate.
Since we don’t need to be so precise with the pressure level to be used, we can also rule out the
use of inflatable cuffs with a manometer unless for whatever reason we want to have that data.
But as we have seen in this chapter and as researchers have demonstrated, it's not necessary to
be so precise with the pressure we use to restrict blood flow to the point of needing a device with a
manometer.
Many years ago, it was thought that it was necessary to control the pressure level more precisely,
but today we know perfectly well that it's not necessary to have an exact control, we simply have to
use a pressure that is sufficient, but without causing discomfort.
It should also be considered that during exercise the pressure increases by about 20%, so if at
rest and without exercising we already feel too much pressure, it's
advisable to loosen the bands since during exercise the pressure will increase a little more,
according to Crossley [137] during exercise the pressure increases by about 20%.
Devices with inflatable cuffs and monometer are still a big business for some and are the main
reason why many people are reluctant to try BFR training because they think they are necessary to do
it properly and these types of devices are usually expensive.
But as we have seen, they are not indispensable at all, since it's not necessary to control the
pressure as precisely as originally thought. Although today many continue to spread that an exact
pressure control level is necessary and therefore a device with a manometer is necessary. When you
come across someone claiming this, it can only be because of one of two possibilities, the first one is
ignorance and the second one is out of interest.
As if all these data were not enough, a meta-analysis has just been published [143] in which the
researchers conclude that when the loads used in BFR training are 30% of 1RM or higher, there will
be no difference in adaptations using higher pressure levels. Therefore, the application of high
pressures is unnecessary when the exercise is performed with loads of more than 30% of 1RM.
According to the conclusions of the meta-analysis by Queiros et al. of November 2021 [143]
where they observed that there is no difference between using a pressure level of 40-50% versus
levels of 80-90% of the arterial occlusion pressure. The only difference between using higher pressure
levels is a greater sense of discomfort and greater neuromuscular fatigue [144][143].
In any case, BFR training is very broad and the possibilities that open up when it comes to
controlling new parameters are many. If you are a geek, you may be interested in monitoring or
measuring a progression not only of loads but also of pressure (this in hypertrophy and with loads of
more than 30-40% of the 1RM would be meaningless).
But even so, in the case that you wanted to have a pressure control it would be necessary to
have an inflatable device with a monometer with which to adjust the pressure to keep track of it and
assess if you are interested in a progression or adaptation in that sense.
In any case, when the use BFR is with the purpose of obtaining gains of hypertrophy and strength
I don’t see necessary to have a registry and pressure control, since it has been seen that with the
simple fact that it is of 50% of the AOP (arterial occlusion pressure) it's already sufficient to have all
the adaptations and improvements that are given with the BFRT. It would be much more interesting
and useful to keep a record of other variables such as the intensity of the sets, the volume of training,
or the density BFR sessions.
Keeping a progression of pressure level would make sense in bedridden or non-mobile patients,
where there is no contraction of any kind, and therefore the only variables in which there can be
progress are the time of use and the pressure level used, which in addition, when there is no
movement, a somewhat higher pressure is usually used.
It may also be of interest to monitor and progress the pressure level when BFR is used for other
purposes, such as improving aerobic performance. If the intensity of the sessions is always going to
be the same, it might be interesting to know more accurately the pressure level of the different training
sessions and to progress in that sense to some extent as well.
However, in a training with the objective of obtaining hypertrophy, when variables that are a priori
much more important come into play, for example, the percentage of 1RM used in the exercises, I find
it more interesting to control this variable instead of the pressure level.
How to measure BFR band pressure subjectively
The pressure to be used with the BFRT can be measured subjectively.
To measure the pressure subjectively we can think of a scale from 0 to 10, where 0 is no pressure
and 10 is a total occlusion veins and arteries (which we don’t want under any circumstances).
From there, the pressure we should use would be approximately 7 out of 10 for the legs, and for
the arms, whose perimeter is smaller, we should lower the occlusion pressure a little, so 6 out of 10
would be fine.
There is no need to be exact, since we have seen that we have a wide margin in the pressure
level without altering the blood flow restriction level.
In any case, it appears that a person can be quite accurate in measuring pressure subjectively. In
fact, there is a 2018 study by Bell et al [138] investigating what accuracy level a person can have in
self-regulating pressure according to their perception on a scale of 1 to 10.
The results of Bell's study in which the sample was 120 people, suggest that subjectively, a
reasonable accuracy can be achieved when measuring band pressure [138].
Capillary refill time
Another system by which we can determine whether we are using a correct pressure or whether
we have excessive pressure that produces too much arteries occlusion would be by means of the socalled "capillary refill time (CRT).
The CRT is the measure of time it takes for the capillary bed to recover its color after pressure is
applied. CRT is used in clinical settings to evaluate different populations such as children [145] and
the elderly [146] with various health problems such as circulatory failure, hemorrhagic fever, or
peripheral perfusion.
Capillary refill time is performed by applying pressure with a finger to certain areas such as
hands, feet, fingers, etc. When an area is pressed, it will be deprived of blood supply, therefore when
the finger that performs the pressure is removed, the area will be momentarily white and immediately
after it will return to its natural color.
The time it takes for the area to recover its color will result in the capillary refill time (CRT). From
there the time it takes for the pressed area to recover color, that is. if the CRT takes more than a few
seconds depending on the population and where it was measured (finger, hand, foot, leg, etc.), it will
be considered that there is a health problem or a sign of poor perfusion (poor blood circulation
supply).
During BFR training we can determine the pressure level or blood flow restriction using CRT.
To determine the CRT in legs and to be able to deduce if the flow restriction is correct or if on the
contrary it is too high, it would be necessary to press with the thumb on the quadriceps muscle above
the knee (for the pressure cuff of the leg) and after a few seconds release to check for how many
seconds the blanched area was and then return to its normal color. If the blanched area returns to its
normal color in 2 or 3 seconds, the pressure and restraint level would be correct, if it takes more than
3 seconds it could indicate that the restraint level is too high.
In the case that we would like to do the CRT test to determine if the pressure and restriction of
blood flow is correct in the arms, we should press with the thumb on the palm of the hand for a few
seconds and then remove the thumb and observe how quickly the blanched area returns to its normal
color. If it takes more than 3 seconds it would indicate that the pressure and therefore the blood flow
restriction level may be too high.
Basically, in the case that we use capillary refill time to determine if the pressure is correct, we
should keep in mind that the normal color should be recovered in 2-3 seconds, if it exceeds 3
seconds, it's quite likely that the pressure is excessive and the restriction level occludes the arteries
too much, which is not what we are looking for with BFR.
An important point to keep in mind is that capillary refill time is not an infallible method either, it's
very useful to check if we have doubts about whether we are overdoing it with pressure, but as
reported by Anderson et al [147], although CRT is a method used in clinical settings, its reliability is
not 100% because environmental and individual factors can influence the patient's outcome.
Use of CRT in BFR training is a novelty and will need further research to provide more details on
this technique and its reliability.
TYPES OF BFR TRAINING
Blood Flow Restriction in the absence of exercise
Applying BFR in the absence of exercise has been found to be useful in immobilizations and in
circumstances of total inactivity and muscle disuse, as simply applying BFR attenuates the loss of
muscle mass and strength [39][38].
When used for this purpose, much higher pressures of 70% to 100% occlusion should be used
[5].
It should be kept in mind that the limb on which BFR is applied is immobilized, therefore, to obtain
any kind of positive effect, the restraint required will be higher. For this reason, when BFR is used in
the absence of any physical activity, the pressures usually used are higher and can be 70% to 100%
of the maximum occlusion in some cases.
The frequency in which BFR is used in circumstances of immobilization is usually once or twice a
day and the way in which it's used is in sets or intervals of about 5 minutes. Generally, between 3 and
5 sets of 5 minutes are performed in each session.
The width of the device that is usually used for this type of restriction can be of any size, that is, it
could be about 5cm (small), about 10cm which would be a medium size, or a larger size. It should be
taken into account that what is sought is an increased restriction, the use of a device with a larger
width will be more efficient, since a greater occlusion is achieved without having to exert so much
pressure on the limb.
In our case, as strength athletes, this way of applying the BFR could only be useful if due to injury
we could not train a certain limb, or we were simply bedridden due to an illness.
The general recommendations commonly employed in the use of occlusion bands with the aim of
attenuating muscle wasting in circumstances where there is no mobility are those given by Patterson
et al [5] in their review on methodology, application, and safety considerations for the use of blood flow
restriction bands.
These recommendations basically consist of applying BFR once or twice a day, at 5-minute
intervals, between 3 and 5 sets with 3-5 minutes of rest and at 70-100% occlusion pressure.
BFR prescription model at rest or in the absence of activity (Patterson et al. 2019)
Frequency
1-2 per day (while at rest, in bed, or immobilized)
Restriction time
At 5-minute intervals (or sets)
Sets number
3 to 5 sets
Rest between
3-5 minutes
sets
More pressure needed, between 70-100 arterial occlusion pressure
Pressure
(AOP)
Restriction Type
Continuous restriction
Bracelet type
5cm (small), 10-12cm (medium), or 17-18cm (large)
Blood Flow Restriction with aerobic exercise
Another situation in which it would be possible to apply BFR would be during aerobic exercise,
either walking or pedaling.
With this type of protocol, we can expect to maintain the total muscle mass of the extremities and
probably also positive effects at the vascular level.
In untrained people, the simple fact of walking with occlusion bands already brings moderate
increases in muscle mass [35][36][18].
In fact, Abe et al [35], demonstrated that a walking protocol combined with BFR at a pressure of
160-230 mmHg twice daily for 3 weeks was effective in increasing muscle cross-sectional area and
volume by approximately 6% in each leg in young adults.
The increases in muscle size were also accompanied by increases in maximal dynamic strength
(i.e., 1-RM), and isometric strength also increased.
A year later, the same team of Takashi Abe et al. replicated the trial but this time the sample was
older men to see if increases in muscle mass also occurred and indeed the results were replicated
[18].
In another 2011 study, this one by the team of Ozaki et al [148] which was conducted on older
adults, the sample also included women aged 53-73 years. The intervention consisted of 10 weeks of
walking combined with BFR. The walking sessions were 20 minutes in duration and were performed 4
times per week. A 140 mmHg at 200 mmHg BFR pressure was used.
At the end of the study, the authors reported significant increases in muscle cross-sectional area
(3%) and volume (2.7-3.7%) in the thigh region, as well as in isokinetic strength (8-22%) and
functional performance.
The adaptations observed with BFR aerobic exercise are not limited to BFR walking. The team of
Abe et al. observed significant increases in lower body skeletal muscle size and volume and improved
oxygen uptake after 8 weeks of BFR cycling [149]. Although the improvements in this intervention
didn’t reach statistical significance.
The most common recommendations when using blood flow restriction during aerobic exercise
according to Patterson et al. in 2019 [5] would be these:
Aerobic exercise prescription model with BFR by Patterson et al in 2019
Frequency
2-3 times per week (>3 weeks) or 1-2 times per day (1-3 weeks)
Intensity
Less than 50% of VO2 max or maximum heart rate
Restriction time
5-20 minutes per exercise
Place to apply BFR
Small or large muscles (arms and legs), bilateral or unilateral
Pressure and sets
Interval sets or single set, 40-80% of arterial occlusion pressure
types
(AOP)
Bracelet type
5cm (small), 10-12cm (medium), or 17-18cm (large)
Exercise type
Cycling or walking
According to Patterson, if the exercise is to be performed for more than 3 weeks, aerobic exercise
with BFR is recommended only 2 to 3 times per week. If the exercise is to be performed for less than
3 weeks, it can be performed daily or even twice a day.
The time of the sessions should be between 5 and 20 minutes, not exceeding 20 minutes in any
case since longer sessions could involve risks.
It's very important that the exercise intensity be kept below 50% of the maximum oxygen
consumption or the reserve heart rate.
The thickness of the occlusion band that we can use for aerobic BFRT is indifferent, both small,
medium or large thicknesses are valid.
An important point to bear in mind when reviewing the recommended protocols is that they are
based on the available evidence, taking safety first and foremost into account, but they are not
necessarily the most suitable protocols for everyone. This can be extrapolated to any other protocol
based on the current evidence, which is scarce and always in people not adapted to BFR training. It
should be kept in mind that many more studies are probably needed, if possible, combining the
experience of coaches and researchers to find the best protocols for each athlete depending on his or
her adaptation to BFR training level.
Delving a little deeper into how curious it's that muscle mass can be gained just by walking with
occlusion bands, we will see in a little more detail the protocol used by Abe et al. in the first study of
this type in which increases in muscle mass were achieved in just 3 weeks [36].
In this intervention, which lasted 3 weeks, 6 sessions were performed per week and were divided
into several sets in which BFR was applied. There were 5 sets and in each one of them they walked
with BFR for 2 minutes and then rested for 1 minute, so the total time they were walking was 10
minutes 6 times a week. The pressure they used was from 160 to 220 millimeters of mercury (mmHg).
In this image [36] we can see the differences in hypertrophy between the group that performed
the exercise with BFR and the group that performed the exercise without BFR.
The researchers observed an increase in quadriceps cross-sectional area.
And as I always say, more muscle equals more strength, and that's what the researchers saw.
The group that performed the exercise with BFR also had improvements in strength over the group
that didn’t use BFR.
It should be noted that the Abe et al. study sample was sedentary [36], healthy but sedentary.
Almost certainly a trained person is not going to obtain muscle mass gains with only 3 weeks of
walking with BFR, at least not with the protocol that was used in this study.... But this intervention
gives us an idea of how well it could be used to maintain muscle mass if for some reason we were
unable to train lower body strength.
It's important to note that the recommended protocols are the ones we have seen in this section,
but they are not the only ones. As I mentioned earlier, much more research is needed on the
application of BFR during aerobic exercise and it's necessary to clarify the mechanisms by which
adaptations in hypertrophy, strength, and other types of adaptations at the cardiovascular level are
produced.
In our case, we are mainly interested in hypertrophy and strength adaptations, but these are not
the only adaptations that can be improved with the use of occlusion bands and aerobic training.
Seeking to improve adaptations at the mitochondrial level and improvements in maximal oxygen
consumption, the researcher Emma A. Mitchell et al [150], conducted a study with professional
cyclists in which BFR was applied for 4 weeks in SIT (Sprint Interval Training) sessions. But contrary
to what one would think, the blood flow restriction was done during rest intervals and not during sprint
intervals.
What they observed was that oxygen consumption increased by up to 5% despite the fact that
these were professional cyclists with very high oxygen consumption. In addition to this, positive
adaptations at the mitochondrial level were also observed.
With these recent investigations such as that of Mitchell et al.,2019 [150] or his teammate
Ferguson el al.,2021 [151], what is sought is to use blood flow restriction as a strategy to increase
exercise-induced stressors, and thereby also increase subsequent molecular signaling responses,
with the aim that the resulting adaptations improve the endurance physiological characteristics of
athletes.
There is more and more research in this regard as the results being seen with these interventions
are truly astounding and interesting in equal measure.
However, much remains to be clarified regarding the underlying mechanisms leading to muscle
hypertrophy with BFR aerobic training.
Acute release of anabolic hormones has been proposed as one of the possible mechanisms. It
has also been speculated that a possible exercise induced metabolic response during aerobic
exercise with BFR could facilitate recruitment of the more hypertrophy-prone type II muscle fibers.
Another mechanism suggested to explain the hypertrophy that occurs with aerobic exercise and
BFR is that elicits a set of positive neuromuscular adaptations due to exercise-induced muscle
swelling.
Although the truth is that very little is known about the effects of aerobic exercise with BFR and
more specifically about the muscle swelling it produces, especially when walking. It does appear that
some acute muscle swelling does occur after BFR aerobic exercise. In fact, the team of Ogawa et al.
observed significant increases in muscle thickness after just one session of BFR walking [152].
It has also been speculated that modulation of biomolecular pathways governing muscle protein
turnover, such as Akt / mTOR and myostatin, could contribute to the response to aerobic exercise with
BFR. But today, however, none of the hypotheses under discussion has yet been fully demonstrated.
Much more research will be needed to elucidate the mechanisms by which hypertrophy
adaptations occur with BFR aerobic training.
Blood Flow Restriction in strength training
In this chapter we are going to see how blood flow restriction training should always be applied
according to the recommendations proposed by researchers.
The most used guidelines and recommendations based on all the scientific evidence available so
far with blood flow restriction training with the aim of obtaining gains in muscle mass and strength are
those of Patterson et al. in 2019 [5].
We can say that these are the recommendations proposed by the scientific evidence according to
the current literature, but they are still very generalist indications and guidelines that, although they are
a good starting point, are by no means the only way there is to train with BFR, nor are they an
immovable law on which we cannot make variations.
Like most things in life, the most fun things happen when certain rules are broken. In this book we
will not depart from the protocols proposed by the researchers, and which have been found to be safe
in the literature available to us, since the aim is that it can be a useful guide on how to apply BFR
training effectively and safely, and to do so we must adhere to the official recommendations.
But I do want to make it clear that these recommendations proposed by the researchers don’t
necessarily have to be the most effective, although they are undoubtedly the most advisable to start
using the BFRT and then, as one adapts, one can increase the difficulty and level of demand training.
The frequency of BFR training proposed in Patterson's review is 2 to 3 times per week when we
are going to be training with BFR for more than 3 weeks. But in the case that we are going to be or
less than that time we can use the BFR up to two sessions a day.
The load to use should be between 20-40% 1RM. The percentage of load to use could depend on
the subject level. An untrained or inexperienced subject should move with loads of 20-30% of their
1RM since higher loads will produce greater metabolic stress and will require a period of adaptation.
On the contrary, trained subjects could move quietly with loads of 30-40% of their 1RM, and even
a little more depending on the experience they have with the BFRT and the occlusion level they use
and tolerate. But as these recommendations are generalist and based on current scientific evidence,
we are going to keep for the moment in loads of 20-40% of 1RM.
The 1RM calculation for each exercise can be very complex and inaccurate, even more if we
consider that in most of the exercises that we use the occlusion bands will be isolation exercises and
in them it's very complicated and inefficient to calculate the 1RM. So instead of basing ourselves on
percentages of 1RM we can perfectly make some equivalences and instead of thinking of a 20% of
1RM think of doing 32/40 repetitions, a 30% of 1RM would be equivalent to approximately 28/32
repetitions and a load of 40% of 1RM is the one with which we could do approximately 24/28
repetitions.
Obviously, the estimated number of repetitions is individual and very variable. We must think that
if we use, for example, a load of 30% of 1RM in which we can perform 30 repetitions in the first set, in
the second set, even using the same load, the number of repetitions will drop considerably.
Perhaps 3 sets with a load of 30% of 1RM could look like this: 1 set 30 repetitions, 2 set 25
repetitions, 3 set 20 repetitions. Even using the same load, which in the beginning was 30% of 1RM,
as the sets progress the number of repetitions will inevitably decrease due to fatigue.
Therefore, if we want to maintain the same range of repetitions, we will have to lower the load. As
to whether it's convenient to lower the load or not, it will depend on the objective we have with the
training and the limitations of each one. If, for example, someone uses the BFRT because it's
impossible for him to handle loads higher than 20% of his 1RM, in that case it's probably a good idea
to lower the load in each set to stay in that range of his 1RM, but if there is no impediment to apply a
greater effort it may make more sense to leave the same load for the next set.
One point to keep in mind is that BFR training has been shown to be ineffective with loads of 15%
of 1RM and with that percentage of 1RM it has been seen to produce no improvement over training
without BFR as could be seen in the study by Samuel L. Buckner et al [153]. So, to ensure a good
stimulus, I would personally try to reach failure always before 35 repetitions to be absolutely sure that
the load being used is greater than 20% of 1RM.
Thinking about the percentage of 1RM when planning training can be tricky, so to make things
easier you can think in reps and from the reps know the percentage of 1RM.
I leave this table here so that you can roughly make the conversion from percentage of 1RM to
repetitions more easily.
% of 1RM (Maximum repetition)
100
95
Approximate number of repetitions
1
2
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
3-4
5-6
7-8
9-10
11-12
13-15
16
17-18
19-21
22-23
24-27
28-29
30-31
32-34
35-38
In the photo, a set with BFR in squat on machine with 300Kg at 12 repetitions (70% of 1RM).
Maximum recommended time with BFR
As for the maximum time of blood flow restriction, what the researchers propose according to the
available literature is that in the total of a session the threshold of 20 minutes with BFR should never
be exceeded. So, each exercise could have a duration of between 5 and 10 minutes without
exceeding 10 minutes per exercise or 20 minutes in the total session.
Knowing that we have a maximum of 20 minutes per session and 5/10 minutes per exercise we
can choose to release the blood flow at breaks or keep the flow restricted for the entire BFRT session.
Intermittent BFR Training
In principle, maintaining the restriction whenever possible might seem to be the best way to
achieve the maximum effects and adaptations that we are looking for with BFR training. But the truth
is that there is evidence indicating that there seems to be no significant difference between performing
a continuous BFR throughout the session or an intermittent BFR in which we loosen the bands in the
breaks between sets or when changing exercises.
In a study published in March 2021 Schwiete et al [154] wanted to test the differences in maximal
strength, hypertrophy, fatigue endurance, and perceived discomfort when training with constant BFR
or removing the BFR at rests between sets.
The results and conclusions of Schwiete trial were similar in terms of strength, hypertrophy, and
fatigue endurance, but they did find that the group that maintained BFR at rest reported a higher
degree of exertion (RPE) and somewhat more soreness or discomfort as compared to the group that
performed intermittent BFR and loosened the bands at rest.
It should be noted that the subjects in this study, although they were trained subjects were not
advanced, and only applied BFR in two weekly sessions of four sets (30-15-15-15-15) of leg press at
20% of 1RM for 6 weeks.
Other limitations of the study are that each subject did their normal training routine and simply
added to the routine that they were doing those 4 sets of leg presses with BFR, so the rest of the
training volume was not considered, and perhaps the most important limitation is that there was no
control group that trained without BFR to be able to assess whether the group without BFR obtained
the same results.
The trial by Schwiete in 2021 et al [154] to test whether there was a difference between having
the bands on throughout the workout or loosening them between sets is not the only study on
intermittent BFR.
We also have the 2013 study by Yasuda et al [155], in which they saw that reducing the pressure
between sets didn’t appear to diminish the effects of BFRT and was as effective as when continuous
BFR protocols are employed.
Perhaps in the long term or in more advanced subjects if there could be differences, but for now it
gives us an idea that to start adapting to BFR training, we can perfectly well loosen the occlusion
bands without losing part of the adaptations in terms of strength and hypertrophy. At least in an initial
phase of BFR training, since this type of intervention has not been done with athletes who already
train with BFR on a regular basis.
Recommended pressure with BFR
The pressure at which we should place the bands is between 40% and 80% where 100% would
be a total occlusion. This will depend on the load we use, the session time, and the extremity to which
we apply the bands. If, for example, the session is going to be a long one of about 20 minutes,
maintaining a pressure of 80% or, in other words, a feeling of occlusion of 8 out of 10 may not be a
good idea, and even less so if the loads we are going to use are closer to 40% of 1RM than to 20% of
1RM.
If, on the other hand, we are going to use very light loads and for a short period of time, it would
be possible and even advisable to increase the pressure slightly in order to maximize the benefits of
the BFRT.
Regarding the pressure level, it should be considered that the legs can tolerate slightly more
pressure than the arms. Above all, it's very important that the bands are never over-tightened to the
point of being painful or excessively uncomfortable, and if we notice discomfort or any other bad
sensation, the bands should be loosened immediately.
Sets and repetitions approach
The exercise approach proposed in the literature [5] is about 75 repetitions per exercise where a
distribution of 4 sets per exercise could contain approximately these repetitions 30 x 15 x 15 x 15 x 15.
In such a case, total of the 4 sets would result in 75 repetitions.
The rests between sets should not exceed 60 seconds and can be much shorter and the
restriction should be around 40-80% of the arterial occlusion pressure.
The researchers recommend a high number of repetitions in each set and the rests are proposed
to be short because in principle, what we are looking for with the BFRT is to generate a high metabolic
stress.
In the following table we can see the guidelines proposed by Patterson et al [5] to perform training
with loads and BFR with the aim of improving hypertrophy and strength.
BFR Prescription Template for STRENGTH TRAINING
Frequency
2-3 times a week (>3 weeks), or 1-2 times a day (1-3 weeks)
Restriction time
5-10 minutes per exercise (revascularization between exercises)
Load
20-40% of 1RM
Sets number
2-4 sets
Rest between sets
30-60 seconds
Repetitions
About 75 repetitions total, e.g. 30 x 15 x 15 x 15 x 15
Execution of the
Until concentric failure or until completing the planned repetitions
sets
1-2 seconds for concentric phase and 1-2 seconds for eccentric
Cadence
phase
Continuous or intermittent restriction (rest between sets and
Restriction Type
exercises)
Restriction Type
Continuous restriction
Restriction time
5-20 minutes per exercise
Place to apply BFR
Small or large muscles (arms and legs), bilateral or unilateral
Bracelet type
5cm (small), 10-12cm (medium), or 17-18cm (large)
This would be the protocol proposed by Patterson and other researchers based on the literature
currently available and with the objective of obtaining maximum benefits while minimizing risks. But
the protocols that can be used with BFRT can be much broader and can be modified and adapted
individually depending on the experience of users and trainers.
As with conventional training, BFR training also seems to respond better at higher training
volumes. In the 2005 study by Yasuda et al [53], they were able to demonstrate how improvements in
strength and hypertrophy were obtained in only 2 weeks with loads of 20% of 1RM. In the protocol of
this trial, they trained 3 days a week, but two training sessions each day and in only two weeks
training 3 sets of two exercises (double session) with 20% of 1RM they obtained gains in strength in
the squat exercise and an increase in muscle cross-section.
We should also keep in mind that it is not always necessary to use loads as low as 20-40% of
1RM. While my recommendation is to start with those types of loads and work at repetition ranges
commensurate with those 1RM percentages (between 22 and 35 repetitions). There is also evidence
that loads of 50% of 1RM (or more) can be used with good results.
Training with BFR and loads over 40% of 1RM
An example of an BFRT in which 50% loads were used can be found in the trial by Takarada et al
[156]. In this trial, the sample was professional rugby players (that is, highly trained athletes) with
more than 5 years of experience with loads.
In this study, in order not to interfere too much with their training schedule, the athletes simply had
8 sets at failure added to their usual training (divided into 2 sessions per week for 8 weeks). The load
used for the trial was 50% of 1RM.
The sample was divided into three groups. On the one hand, a group of 6 athletes who used
BFR, another 6 athletes who didn’t use BFR, and a third control group of 5 athletes who didn’t perform
the additional sets.
What happened in this trial was that the group that experienced the most gains in strength and
hypertrophy was the group that used BFR. This group that added BFR went on to increase quadriceps
cross-sectional area hypertrophy by 12%. A 12% increase in elite athletes is quite a significant
difference, especially considering that the group that didn’t use BFR didn’t increase hypertrophy at all.
There are many studies with similar results, but the study by Takarada et al [156] has the
particularity that they used loads of 50% of 1RM, which is not usual in these interventions, hence its
mention.
As we can see, there are many ways to include blood flow restriction in our training routine and
there are many and varied protocols for its use.
Later we will see a more practical section with exercises and protocols, but to start with BFR
training in a safe way. Basically, these are the protocols proposed in this chapter, but applied to the
different exercises.
It should be noted that with just a few sets with BFR improvements can already be obtained, so
although the initial protocols recommended by the researchers may seem simple and easy, in terms of
results they can be very effective.
In case we don’t want to change too much our way of training, we can obtain benefits by simply
applying the occlusion bands in a few sets of our usual training, and with that simple gesture we will
begin to obtain the benefits of training with BFR.
In addition, the improvements that are obtained with the simple fact of training with BFR in a few
sets of some of our training sessions, is not conditioned to if we are beginners or advanced athletes,
since it has been seen that they obtain improvements by the simple fact of adding a few sets with BFR
to their usual training without the need to make major changes.
Systemic effect with BFR training
Most of the interventions in which the effects of BFR training are studied are performed by
applying BFR to the lower body and, therefore, benefits in strength and hypertrophy are observed,
since this is the object of the research.
However, the benefits of applying BFR to the legs are not only limited to the lower body; in fact,
but improvements in the upper body have also been observed by applying BFR only to the lower
extremities.
To show with a practical example how this systemic effect occurs, we can review the 2014 Cook,
Kilduff and Beaven trial [84].
In this study, the sample was a group of semi-professional rugby players which was divided into
two groups (BFR and control group). Both groups followed a training plan for 3 weeks which consisted
of 9 training sessions (3 sessions per week), which included 5 sets of 5 repetitions of bench press,
squat, and weighted pull-ups.
What was observed in this trial was that the group using BFR improved strength in both the squat
and bench press (even though the BFR was in the legs) and saw increases in hypertrophy.
A curious fact is that in addition to the increases in performance for the exercises performed with
BFR, they also improved their performance in running and vertical jumping quite significantly
compared to the group that didn’t apply BFR.
Image from Cook et al. [84] the solid
line represents the BFR group.
Study authors concluded that the improvements in bench press or sprinting suggests that there
was some sort of systemic effect with blood flow restriction training that led to improvements in
performance in the other activities.
Another thing to note from this trial is that greater exercise-induced salivary testosterone was
observed in the subjects employing BFR.
We know that BFR training generates higher growth hormone peaks (up to 10 times higher than
without BFR), and also higher IGF-1 peaks [10][11][12][13][14][15]. However, with BFR in previous
studies no higher testosterone peaks have been detected than without BFR. In this trial, however,
higher testosterone peaks did occur in the BFR group.
The authors of this trial suggest that these higher testosterone increases may have occurred
because the loads used with BFR, which were 70% of 1RM, were higher than those used in previous
trials with BFR in which there were no significant differences in testosterone peaks [83][27][85][71].
Another possibility is that the sampling methodology (saliva or plasma) may also play a role. In
the Cook et al. trial, samples for testosterone measurement were taken from saliva, whereas in
previous studies the samples were taken from blood plasma.
The recommended load for BFR training is a maximum of 50% of 1RM, but in the 2014 study by
Cook, Kilduff and Beaven [84] that we have just seen, the load used in the BFR exercises was 70% of
1RM or more.
The duration of Cook's trial was only 3 weeks so it is not yet known how employing loads of more
than 50% may affect and whether they offer sufficient safety to employ such loads. Hence, the general
recommendations of the researchers are not to exceed 50% of 1RM.
Although it's not recommended to use loads of more than 50% of 1RM (and I don’t recommend
them either), I can say that in my personal experience with the BFRT I do use loads that without being
maximal (which would be totally inadvisable and meaningless) if they are well over 50% of 1RM, but
as I say you need a lot of experience before using this type of loads safely. In my case I have been
using BFR in all my training for more than two years.
Strength training with BFR in elite athletes
As an example, that BFR training works perfectly in advanced athletes, we can look at the 2019
study by Thomas Bjørnsen et al [80]. In this study the sample was the Norwegian National team of
powerlifters. That is, they were powerlifting athletes with a high level.
As they were active athletes with an advanced level and in order not to overly modify their
planning, the only change made was to add to their usual training 4 sets of front squats at 30% of
1RM with blood flow restriction and only in weeks 1 and 3 of their planning (8 sets in total).
Both at the beginning of the trial and at the end a muscle biopsy was performed to assess
changes, and what was seen was that the type I fibers increased in size significantly. This is strange
since the fibers that normally increase in size are the fast twitch fibers (type II fibers).
However, in the study by Thomas Bjørnsen et al [80], an increase in the size of slow twitch fibers
that are not supposed to have as much growth potential was clearly observed since the fibers that
have the most potential for hypertrophy are the fast twitch fibers (type II fibers).
In the Bjørnsen trial, both the growth of type I fibers and the proliferation of myonuclei increased
significantly. It is in the myonuclei that protein synthesis processes take place, these processes are
necessary for muscle hypertrophy, so the more myonuclei the greater the capacity for hypertrophy.
Myonuclei are also related to muscle memory, it's speculated that a large amount of myonuclei
could be the reason why it's easier to recover muscle mass.
In terms of total hypertrophy, significant increases were seen in the cross-sectional area of the
quadriceps and vastus lateralis superioris in the group that added sets with blood flow restriction.
Regarding strength improvements between groups, an increase in strength was seen in the
specific exercise usually used to measure lower extremity strength (isokinetic peak torque, image A),
but no improvement was seen in the front squat with respect to the group that didn’t add the sets with
BFR (image B).
In this image we can see the researcher Thomas Bjørnsen in 2013 applying BFR in his training and using bandages that are
usually used in powerlifting.
Considering that in this trial a few sets of front squats were simply added at the end of the regular
training sessions, no palpable improvement could be expected with just that small modification.
Furthermore, the same study indicates that the powerlifters in the control group were more familiar
with the front squat.
I think the hypertrophy results are too spectacular for there to be significant gains in strength in
national level athletes who most likely only increase their loads by a few kilograms each year.
The truth is that this study by Thomas Bjørnsen seemed to indicate that with BFR training there
was a significant hypertrophy of the red type I fibers, so Thomas Bjørnsen and his team continued to
investigate and in May 2021 published another study [112] better structured in which it was clearly
demonstrated that with BFR training both types of fibers are stressed but the type I fibers receive even
more mechanical stress [112].
Immediately following the publication of Bjørnsen's team's latest study, Brad Schoenfeld made a
post recommending that athletes training with a hypertrophy goal add BFR to a portion of their training
in order to obtain greater increases in hypertrophy of type I fibers.
BFR TRAINING GUIDE FOR HYPERTROPHY AND STRENGTH
BFR training can be added into any training routine or programming with the goal of gaining
muscle mass. BFR can be used with body weight exercises, elastic bands, gravitational weight
training, machines, pulleys, etc.
You can use BFR training to finish a workout with weights and get improvements in hypertrophy
and strength just by adding a few sets at the end of the workout.
If, for example, you have a back and biceps day you can add BFR to the biceps exercises, or on
chest and triceps day do all the chest exercises you have in the routine as you have been doing them
and then add BFR to perform the triceps exercises.
The possibilities with BFR training are endless. For example, you can use BFR in a single arm
superset session or even use it as the second workout of the day without negatively affecting
recovery, although the latter is already very advanced and only recommended for experienced
athletes who need or want to perform a high volume of training.
These are just a few examples of how to implement BFR training quickly without having to modify
anything in your training, but in this chapter, we will look in more detail at set and repetition protocols
for specific exercises.
How to place the occlusion bands
In principle, blood flow occlusion bands should only be placed in two places on the body for safety
reasons. On the upper arm and the upper thigh.
On the arms
Occlusion bands are placed just where the anterior shoulder ends and the biceps begins.
Practically the band should be felt under the armpit, since the triceps is a larger muscle than the
biceps it's possible that the band may not be able to completely isolate the triceps in its entirety, there
is no problem with that, it's totally normal.
The objective in placing the bands on the arms is to restrict the venous return of the main veins
which are the brachial and cephalic veins. These veins are also the most superficial and therefore
most susceptible to restriction. However, the pressure in the upper extremities should not be too high
because we want the humeral artery (also called the brachial artery) to continue to send blood to the
extremity.
Anatomy image of the
superficial arm veins and arteries.
On the legs
Occlusion bands are placed on the upper legs, where the thigh begins and just below the area
occupied by the buttocks.
The occlusion band should be close to the groin, but should not interfere with movement.
Occlusion bands are usually very uncomfortable if they rub against the skin, so to minimize discomfort
they should be placed over the pants in order to protect the skin.
In the lower extremities the restriction is applied to be able to restrict the femoral vein, but at the
same time it's necessary to try not to restrict the femoral artery which is in charge of transporting
oxygen and nutrients to the muscle.
Image of the superficial veins and arteries
In the trunk it would not make sense to apply the restriction since there are no remarkable veins
that we can restrict and it would not be a good idea to accumulate blood around the organs, I think we
all agree on this point.
Forearms and calves
The application of the bands on the forearms and calves doesn’t make sense to the researchers
either, since if the occlusion bands are already restricting flow in the upper extremity, it implies that
restricted flow also reaches the lower extremity such as the forearms or calves. Moreover, the risk of
injury or damage to a vein or nerve is greater in these areas.
While it is true that some researchers don’t recommend the use of occlusion bands on the calves,
this doesn’t mean that it cannot be done. Depending on the athlete's experience, he or she may prefer
to place the bands on the calves. In my case, I do apply blood flow restriction on the calves, since the
sensations obtained are not much different when the restriction is on the upper thigh.
Placing the occlusion bands just below the knee to restrict blood flow in the calves may have a
more pronounced effect on oxygen restriction in the calf area which would in principle be more
effective for a more direct stimulation area.
Many people place the bands in that area and usually have no problems, but the truth is that
according to the researchers it could be somewhat dangerous mainly due to the large number of
superficial nerves that exist in that area and that could be damaged with excessive and prolonged
pressure.
Placing occlusion bands on the upper leg already confers benefits in restricting blood flow to the
calves as well, so placing the bands below the knee to restrict calf flow is a matter of personal
preference, but it must be understood that there may be some risk involved.
As the use of occlusion bands on the calf is not recommended, I will not recommend them either
as they have a higher risk, but in experienced BFRT athletes and using adequate pressure and for a
short time there should be no problem. I do use them on my calves, and I know I am not the only one
who applies the BFR in that area.
In any case, using the bands on the calves could be considered an advanced form of blood flow
restriction banding, so no one should experiment with it until they have been training with restriction
for quite some time and have a fair amount of experience with this type of training.
Keep in mind that there are several superficial nerves in the area that could be damaged, so it's
important not to overdo it with pressure.
Image of superficial veins, arteries and superficial nerves
Place bands on the calves?
It should be made clear that the researchers don’t recommend using the BFR bands on the
calves, but in case we already have experience with the BFRT and at our own risk and responsibility
want to use the bands on the calves, they should go just below the knee to restrict the blood flow in
the calves. By placing them in that area it could have a more pronounced effect in restricting the flow
in that part, which would in principle be more effective for a more direct stimulation area.
Many people place the bands in that area and usually have no problems, but it should always be
done with caution and without overdoing it with pressure due to the large number of superficial nerves
that exist in that area and that could be damaged with excessive and prolonged pressure.
Placing occlusion bands on the upper leg already confers benefits in restricting calf blood flow, so
placing the bands below the knee to restrict calf flow is a matter of personal preference, but it should
be understood that it may carry more risk especially if excessive pressure is used.
I personally do place occlusion bands below the knee when I want to train the calves, but
researchers don’t recommend their use on the calves. It appears that this use carries somewhat more
risk due to the amount of superficial nerves in the area, so more research will be needed to determine
if the use of restraint bands on the calves is safe and to what degree they may not be safe.
Pressure of occlusion bands
When inflatable occlusion bands are not used and that offer data on the exact pressure, it's
necessary to use the senses and keep in mind that it should feel tight, but also comfortable, in no case
should pain be felt.
Keep in mind that there will be no additional benefit from increasing the pressure of the bands,
since a pressure that is not too high is already sufficient to restrict venous return and produce benefits
at the muscle growth level.
Most of the time, the bands used are either fabric bands with which it's impossible to measure the
pressure, in fact, I recommend inexpensive bands since they have been found to offer the same
advantages as the more expensive and sophisticated bands.
All the details necessary to understand the pressure level to be used and how to adjust the
pressure can be found in the chapter "Pressure level and how to calculate it".
Different types of exercises
Multi-joint exercises
We can use BFR bands to train with blood flow restriction with basic or multi-joint exercises
involving two or more joints and several muscle groups or large muscles (chest, shoulders, back,
legs...).
Studies such as that of Yasuda et al. in 2010 [24], or that of Dankel et al. in 2016 [116],
demonstrate that muscle mass and strength can be gained even in muscles on which BFR is not
being directly applied.
It has been shown [116] that hypertrophy and strength improvements can be obtained in groups
close to the restrictive stimulus, such as the chest, shoulders or back.
Some of the hypotheses that have been put forward to explain how increases in hypertrophy and
strength are achieved in muscles that are not directly affected by blood flow restriction could be due to
the fact that the system detects a greater accumulation of metabolites in the auxiliary muscles (in this
case the arms), and to try to compensate for the help of the synergist muscle it activates much more
the main group that we are stimulating in the multi-joint exercise.
Isolation exercises
We can use the occlusion bands to train with BFR in isolation exercises that work small muscle
areas or involve a single primary joint. These types of isolation exercises are less important in
improving performance, and increasing the load is usually not the priority in this type of exercise.
But they can be used to improve stability and coordination, as well as to prevent injury, in a
context where hypertrophy is not the main objective but rather performance improvement in a
particular sport.
As we can see, the BFR can be applied to practically any exercise, controlling the intensity of
work and also the bands pressure. The only assumption in which BFR would not be interesting is in
those exercises that have a very high technical component, such as a Clean and Jerk, Over Head
Squat, or a Snatch.
In these types of more technically complex exercises, although BFR can be used, it may not be a
good idea since it could interfere with the ability to generate proper coordination for a safe execution
of the exercise.
BFRT loads
When using BFR training, it's not necessary to use loads of 65% or more to obtain hypertrophy
and strength benefits. In fact, BFR training works best when lighter loads are used. Loads of 20% to
50% of 1RM will be more than sufficient to obtain the full benefits of BFR. In any case, although BFR
training has been shown to be effective even with loads of 20% of 1RM, using such an extremely light
load may not be the best option. Loads between 30-50% of 1RM may be more effective.
The load and the percentage of 1RM to be used may be different depending on the exercise to be
performed since in some cases a load of 30% of 1RM will be more interesting and in others a load of
40% of 1RM or more.
Most of the studies in which it's seen how BFR training increases muscle mass and strength, use
loads ranging from 20% to 40% of 1RM.
Since our goal is to increase muscle mass as efficiently as possible, it would be wise to start
training in those ranges and based on the recommendations and protocols of the researchers which
are detailed in the book.
Once we are advanced in BFR training we can use much higher loads and incorporate our own
protocols, for example, weight drops, rest pause and other types of advanced techniques together
with BFR, but I have already said that these types of techniques have no scientific backing, so in case
of using advanced protocols with BFR we must consider that there is no data available on how safe
they are.
In any case, although at first the loads to be used may seem to be very low, due to the BFR the
sets will have a high difficulty component. As I explained above, the slow twitch muscle fibers will be
quickly exhausted which will make the load used feel much heavier and will require the recruitment of
high threshold motor units that innervate the white fibers to continue with the sets. You will be able to
verify that with BFR it's not necessary to use too high loads to completely fatigue the muscle and
obtain the sensations of a good workout at the end of each set.
In fact, as far as hypertrophy is concerned, a load of between 20-40% of 1RM with BFR and
taken to muscle failure or very close, causes a hypertrophic stimulus like when using loads of 70-80%
but without BFR. The fatigue level that is generated is also similar, so thinking that training with BFR is
less intense is a complete mistake, training with BFR and light loads produces a neural and local
fatigue as great as training with traditional loads, even at the beginning when one is adapting to this
type of training may even notice more fatigue, so it's best to start with the BFRT progressively.
The most common with BFR training is to use loads of 20-40% of 1RM. This would be equivalent
to performing between 22 and 35 repetitions in each set. Choosing the load based on the percentage
of 1RM can be a complicated task, so in the practical examples we will think about the repetitions we
have to reach instead of thinking about 1RM.
Table of 1RM percentages and number of repetitions
Here below we have a table so that we can easily convert the 1RM percentage to repetitions.
% of 1RM
Approximate number of reps
(Maximum repetition)
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
1
2
3-4
5-6
7-8
9-10
11-12
13-15
16
17-18
19-21
22-23
24-27
28-29
30-31
32-34
35-38
It should be noted that any table in this sense will always approximate reality but cannot be 100%
accurate. Since the number of reps that a subject can perform with a given percentage of 1RM will
depend on what type of training he/she is more adapted to (high or low repetitions). But to get a rough
idea, this table serves its purpose very well and it's much more practical to think in repetitions rather
than in percentages of one repetition maximum.
Anyway, the range of loads that we can use is very wide, especially when we have experience
with the BFRT, and although most studies have been conducted with loads between 20-50% of 1RM,
there are also interventions where loads of 70% have been used with very good results.
In any case, my recommendations for someone starting with BFRT is always going to be to use
loads of 20-50% of 1RM especially in the first weeks or even months of training. Once a high degree
of experience and adaptation to BFR training is achieved, it's possible to increase the loads and time
of use progressively.
However, there are no long-term studies that have tested whether it's safe to use BFR at high
loads. Most studies are performed with light loads and are limited to about 8 weeks. So, if you do use
higher loads with the BFRT you should do so very carefully and at your own risk.
However, we know that without using high loads and high occlusion pressures, very good results
can be obtained. So, it's much better to stick to the recommendations of the researchers at least until
you are really well adapted to BFR training. Above all, use the BFRT with caution and in case you
want to increase the difficulty of the training, do it in a very progressive way exactly as you would do in
any other type of training.
Training volume
The recommended volume according to the evidence we have is between 50 and 80 repetitions
per exercise and it’s not necessarily necessary to reach muscle failure. Although in my opinion it is
advisable to reach muscle failure or at least stay very close to it, especially when it comes to analytical
exercises.
While it is true that BFRT without reaching muscle failure has been shown to be just as effective
as reaching muscle failure (Sieljacks et al., 2018) [157], reaching failure is more effective in inducing
neuromuscular adaptations as well (Jessee et al., 2019) [158].
Some standard distributions for exercises would be 3 or 4 sets with this configuration of
repetitions.
1 set
40
30
30
25
20
2 set
30
30
25
20
20
3 set
20
15
20
20
20
4 set
15
15
15
15
20
These types of 4 sets protocols in a range of approximately 30-15-15-15-15 repetitions are the
typical protocols used for both traditional (in laboratory) BFR training and more practical (in a gym)
BFRT (Wilson et al., 2013) (Vechin et al., 2015) [26][159].
The rest between sets in isolation exercises where the repetitions per set are as described above
is usually short, 30 seconds to one minute. Then in multi-joint exercises the rest may be lengthened a
bit more in order to achieve a more complete recovery.
The rest is also usually longer when the protocol includes more than one exercise, in these cases
the rest time can be between 2 and 5 minutes.
To maintain the greatest accumulation of blood in the occluded extremities, the occlusion bands
should be maintained at all times during the sets, and the bands may be loosened during breaks,
especially when these are short.
In rests of between 2 and 5 minutes, if we loosen the bands, a great part of metabolites will be
dissipated, so that in long rests it would not be advisable to loosen them. In short rests it has been
seen that there are no differences at least in beginners in BFR training [154][155].
These are the protocols most used in research and in gyms around the world, but they are clearly
not the only protocols that can be used.
Research into the metabolic processes and hormonal responses that occur with the BFRT are
wonderful, but in terms of training systems and ways to apply the BFR to obtain improvements in
hypertrophy and strength the possibilities are very broad and there is still much to be studied in that
regard. It must be considered that in the best of cases the sample in the studies are athletes without
experience with the BFRT, so the protocols to be used must be those that have been reviewed and
validated on this type of sample (athletes not accustomed to the BFRT).
For a person who begins to train with BFR, regardless level or years of training without BFR, it
doesn’t make sense to try to use the BFRT with intensity techniques because they need a previous
adaptation to the BFRT. It is as if someone who is not adapted to training would start using high
intensity techniques.
The use of high intensity techniques in a beginner in training (with and without BFR), will most
likely cause more harm than good, besides the fact that without the need to use advanced techniques
he would progress perfectly well.
In my case, after several years using BFR training, I have used it with several advanced training
techniques such as drop sets, super sets, micropauses, etc. But before thinking about combining the
BFRT with advanced training techniques, you must start with the base, and get a good adaptation to
the BFRT and then in case you want to increase the difficulty and always in a very progressive way,
you can add more advanced intensity techniques, as well as the use of loads over 50% of 1RM.
Training frequency
The frequency of training recommended according to the evidence available will depend on the
objectives and the type of population. It should be considered that BFR training can be used with
different objectives, so, depending on the objective, one training frequency or another will be
recommended.
In terms of health improvement or for clinical population with some pathology, it is recommended
between 2 and 3 sessions per week of training with BFR and low loads, or even only apply BFR in
case there is no mobility. But with 2 or 3 weekly sessions would be enough to obtain positive
adaptations, and these sessions can even be 2 times a day when the period in which the BFR is going
to be used is 3 weeks or less.
In athletes who wish to improve strength and hypertrophy with BFR training, the
recommendations range from 2 to 4 weekly sessions added as an extra to their usual training
sessions with weights. In this approach it would be to perform your usual training and simply add 4/8
extra sets in each session between 2 and 4 times a week.
It has been seen that something as simple as adding a few sets with BFR to a conventional
training program has already seen gains in hypertrophy and strength even in elite athletes. As an
example, we have the study by Thomas Bjørnsen where just by adding 8 extra sets in two sessions (4
sets in each session) improvements in hypertrophy and strength were already seen in national level
powerlifting athletes [80].
The proposed approaches in terms of load, time of use (never over 20 minutes), number of sets
and repetitions, are quite conservative. But it is what’s currently recommended by researchers based
on what has been seen in the most current scientific literature [5].
In any case, I consider that to begin to apply BFR training is the most sensible approach. But it is
true that in my personal experience and that of my environment, I have found that you can increase
the frequency, both in weekly training sessions with BFR, as in number of sets per session.
As with any other training program, if the increase of work is done in a very progressive way
allowing a correct adaptation, there should be no problems. But as I always say and emphasize, the
increase in the demands and the amount of work should always be done in a very progressive way.
In fact, in my case I have been using BFR continuously for years in practically all my training
sessions. I have always used common sense and have never overdone it with the pressure, besides
loosening the band if at any time I have felt too much, and I have never had any problems despite
using loads of well over 50% of 1RM and times that are three times those recommended by
researchers.
However, no studies have yet been done on people with a lot of BFRT experience, so it has not
been possible to evaluate the safety of protocols such as the ones I use, so in this book I will limit
myself to making the researchers' recommendations for protocols for using BFRT.
In the BFR Training Expert course I do go into detail with the protocols and advanced
techniques that I use with the BFRT, and there are dozens of videos with practical examples of the
exercises. But that kind of protocols are advanced and unnecessary for someone who starts with
BFR, for that reason and for the impossibility of showing them in a visual way in a book I will not go
into details.
If you want to see what they consist of or how I train with BFR you can check my YouTube
channel where there are a lot of videos where I use this kind of advanced protocols with BFR. In my
channel there are videos where I use BFR with very high loads and advanced intensity techniques,
but I already said that they are totally unnecessary for someone who starts, besides it is not proven
that the use of high loads and advanced intensity techniques with BFR is safe.
BFR Intermittent YES or NO
Although some trials seem to indicate that removing or loosening BFR bands at rest or between
exercises would not affect positive adaptations to BFR training even when using loads of 20% of 1RM,
there is also evidence that adaptations may be lost when bands are removed at rest.
We have several studies that give us clues as to whether the adaptations are similar by removing
the BFR at rest between sets or keeping it.
In the study by Schwiete et al [154], they found that both the group that removed BFR at rest and
the group that continued BFR during rest reported gains in muscle thickness after 12 training sessions
with BFR.
One of the main limitations of this study is that each participant continued with their usual routine,
and it was different for each participant. What was done was simply to add 4 sets of presses to each
12 sessions that made up the study.
Results of the Schwiete trial were that there were no differences between the two groups, but they
did find that the group that rested between sets without BFR reported a lower degree of perceived
exertion.
In another trial, this one by Yasuda et al. from 2013 [155], they conclude that reducing the
pressure between sets doesn’t seem to diminish the effects of BFR.
Pointing in the opposite direction, we have the study by Okita et al. from 2019 [160]. In this study,
two low-intensity BFR protocols (20 and 40% of 1RM) were compared.
And the study assessed how it affected metabolic stress with intermittent BFR (that is, removing
the band at rest) with loads of 20% of 1RM and also with loads of 40% of 1RM.
In Okita's study, intramuscular metabolic stress was assessed by a decrease in phosphocreatine
and intramuscular pH. And it was concluded that with loads of 20% of 1RM and intermittent BFR
(loosening the bands at rest), it was insufficient to accumulate metabolic stress and that part of this
was dissipated when the bands were loosened.
However, when the loads were 40% of 1 RM, sufficient metabolic stress was maintained during
the rest intervals.
On the other hand, Freitas et al. in 2019 [161], concluded that with intermittent BFR, blood flow
was restored too early and thus metabolic stress dissipated too quickly and this could hinder the
adaptations we are looking for with BFR.
It seems therefore that to obtain the best hypertrophy adaptations it would be convenient to
maintain the blood flow restriction during rest periods, in order to keep the metabolic stress as high as
possible, but it is not entirely necessary, especially when using loads of 40% of 1RM or more.
According to Okita et al. when the load is 40% of 1RM or more, metabolic stress may be
maintained due to the inability to eliminate metabolites during the rest interval between sets.
Another point to consider that is not mentioned in the tests is the duration of the rest. If when we
loosen or remove the bands the rest is less than one minute, it will be difficult to completely dissipate
the metabolic stress even when using low loads, while if the rest is 2 minutes or more it will be very
easy to dissipate the metabolic stress even if loads of 40% or more have been used.
In any case, and to draw conclusion from all this, we can summarize it in that to start adapting to
BFR training, we can loosen the bands at rest breaks as long as they are short regardless load we are
using. Loosening the bands at rest can give us the feeling of less fatigue and will allow us to adapt
well to the BFRT.
Once we are more advanced users, we will not feel the need to loosen the bands at rest because
we will feel comfortable with them. We must remember that the BFR bands should never cause pain
or discomfort, although it’s true that in the first sessions it is inevitable not to be 100% comfortable with
them, it could be very interesting to loosen the bands in the breaks between sets.
Sets and repetitions
As for the most effective training protocols when using BFR, most researchers agree that 3 or 4
sets per exercise, at about 20 repetitions per set and with short rests of about 30 seconds between
sets is what gives the greatest stimulus and therefore greater muscle growth.
Due to the lack of studies with other types of more advanced protocols, researchers don’t
recommend maintaining the BFR for more than 20 minutes, so they recommend finishing the work in
at most 20 minutes and immediately afterwards removing the bands.
These general recommendations are safe and sufficient to obtain improvements with BFR
training, but they may fall short in intensity for someone with a lot of experience, in which case it’s
possible that they could benefit from other types of much more advanced protocols and obtain better
results with them. On my YouTube channel there are a lot of videos where I show much more
advanced protocols using the BFRT, but in this book I will limit myself to give the most common and
recommended indications for the BFRT.
Starting with training and adjusting pressure
The pressure at which to tighten the occlusion bands is extremely subjective when not using
inflatable tires that can give data on tourniquet pressure. The problem with inflatable bands with a
manometer is that in addition to being much more expensive, they are most likely not too practical in a
real training context in the gym, so as we have seen in a previous chapter, they don’t seem to be the
best choice for hypertrophy training in a real environment.
Because with the use of BFR bands without a manometer we don’t have any objective method,
you may not have a good idea at first of what pressure the bands should be at, so you will probably
have to keep adjusting and readjusting the pressure during the first week of BFR training. After that it
will be easy to get a good feeling and comfort at a given pressure.
To get an idea, you should try to try that on a scale of 1 to 10 the pressure you feel is about a 6
for the arms and can be up to a 7 for the legs, that is, that it squeezes but it’s not something
excessively annoying and of course not painful.
About pressure, I talk about it in detail in the chapter dedicated to the pressure that should be
used in the bands and how to calculate the pressure subjectively. But the most important detail is that
the pressure should not be too high to the point of being annoying, since it has been seen that with
relatively low pressures the same results are obtained if loads of more than 30% of 1RM are used,
and with more pressure no further improvement is going to occur.
Initial feelings with BFR training
It's possible that when you perform the first sets with BFR at first the repetitions will be simple and
easy to perform, since the load will be much more compared to what you have been using, but as you
advance in repetitions you will begin to feel that characteristic burning or stinging that will become
more and more evident as you advance in repetitions.
With just a couple of sets with good technique and close to muscle failure or even reaching
muscle failure, you will begin to feel fullness in the muscle you are exercising, and it may even be
slightly painful if the congestion level is very high.
It may happen that as you reach more congestion and accumulate repetitions you will reach a
point where you can only perform partial repetitions due to the large amount of pumping that the
muscle has. At this point you must continue with the sets until you reach muscle failure. We want the
end of the sets to be produced by the inability muscle to generate force (muscle failure), and not that
the sets are abandoned before that moment because of the pain or burning that is felt due to muscle
congestion.
With BFR training, on many occasions the muscle failure feels different since it’s sometimes
accompanied by a great congestion that can even be somewhat painful. This is totally normal, and
even though sometimes the burning gets to be painful you must try to continue with the set so that
failure occurs because you aren’t able to perform one more repetition and not because of the pain
caused by the engorgement. It may be that both happen at the same time, and you stop because you
aren’t able to complete one more repetition and because the pain due to the burning is too high.
It’s likely that during the training session you will notice that the bands are too tight, and you
should loosen them a little. If that happens, loosen the bands a little and continue with the training.
When starting with BFR training it’s normal to be unclear about the pressure to be used and for a few
days you will have to adjust the pressure. With practice this will become less and less frequent, but
above all always remember that it’s preferable to fall slightly short rather than go overboard.
Mind-muscle connection
It must be understood that with BFR training the goal should not be to move high loads, but to get
the maximum possible stimulus on the target muscle. The greater your ability to feel the muscle
contract and stretch, the greater the ability to produce tension in the muscle.
BFR training is a great opportunity to focus on the mind-muscle connection and improve this
aspect, since it makes you aware of how you feel the work on the target muscle and that it’s not the
load you move that is important, but how the target muscle feels that load.
Somehow, we tend to have better developed muscles that we feel better. To give an example, it’s
very rare that someone who feels a great congestion and stimulus in the chest has problems to
develop it, while someone who doesn’t feel the chest when training it, is very likely not to have an
overdeveloped pectoral. This easy-to-understand example can be extrapolated to many other
muscles.
BFR training can improve the sensations you have with the training, and it is easier to better feel
the muscle you are working. So, if you do your part and focus more on getting a good stimulus than on
moving a high load, you will get a very good activation target muscle and therefore a good mindmuscle connection.
You can see how the game changes when, for example, you apply BFR to muscles like the
hamstrings, which with training without BFR are hard to isolate and get that mind-muscle connection,
but with BFR you can notice how the hamstrings feel much better and therefore your mind-muscle
connection is much improved.
The fact of filling the muscles with blood along with the accumulation of lactic acid and
metabolites generates a better congestion, which in turn allows you to have better contraction control
in that muscle, which in turn leads to better workouts, which ends up generating greater gains in
muscle mass. On the other hand, if you work a muscle, but you don't really feel the work, what usually
happens is that the muscle doesn’t grow optimally, as in the example I gave a couple of paragraphs
ago.
Exercises, sets, and repetitions with BFR
In this section we are going to review the most common exercises with which we can use the
BFR bands, and we will see the sets and repetitions that are usually recommended with the BFRT.
Keep in mind that these are only a small part of the exercises that can be done with BFR. Let's
say that these are exercises in which we could begin to apply BFR with the goals of gaining
hypertrophy and strength, but there are many, many more possibilities and variations that could be
done.
Next, let's look at some exercises that we can use to obtain improvements in muscle groups that
are directly related to BFR, or that we can train by causing a restriction of blood flow directly on them,
such as arms (biceps, triceps, forearms) and legs (quadriceps, hamstrings, and calves).
Biceps
Blood flow restriction can be applied to each bicep isolation exercise. I don't think it's necessary to
go through all the existing biceps exercises because compiling them is not the purpose of the book,
but we are going to look at some best exercises or at least some of the most used when employing
BFR.
In principle, the way to start training with BFR would be to simply add some of these exercises at
the end of your arm training or as part training of any other muscle group, that will depend on the
programming of your training.
It should also be noted that both the sets and repetitions are merely indicative. They are
indications based on the recommendations of researchers to start training with BFR in a safe and
effective way.
Undoubtedly, it’s best to start this way, then over time and as we adapt to the BFRT we can use
other ranges of repetitions, other loads somewhat higher, and even add high intensity techniques.
BICEPS CURL WITH BARBELL OR DUMBBELLS AND BFR
SeTs
Reps
% of 1RM
Rest
1 seT
20 reps
50% of 1RM
30-60 seconds
2 seT
20 reps
50% of 1RM
30-60 seconds
3 seT
20 reps
50% of 1RM
30-60 seconds
4 seT
20 reps
50% of 1RM
30-60 seconds
BICEPS CURL ON PULLEY WITH CROSS ARMS AND BFR
SeTs
Reps
% of 1RM
Rest
1 seT
30 reps
30% of 1RM
30-60 seconds
2 seT
25 reps
40% of 1RM
30-60 seconds
3 seT
20 reps
50% of 1RM
30-60 seconds
4 sET
20 reps
50% of 1RM
30-60 seconds
HAMMER CURL WITH DUMBBELLS AND BFR
SeTs
Reps
% of 1RM
Rest
1 seT
30 reps
30% of 1RM
30-60 seconds
2 seT
25 reps
40% of 1RM
30-60 seconds
3 seT
20 reps
50% of 1RM
30-60 seconds
4 seT
20 reps
50% of 1RM
30-60 seconds
SeTS
1 seT
2 seT
3 seT
4 seT
LOW PULLEY BICEPS CURL AND BFR
Reps
% of 1RM
Rest
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
PREACHER BENCH CURL WITH DUMBBELL, BAR, OR PULLEY AND BFR
SeTs
Reps
% of 1RM
Rest
1 seT
2 seT
3 seT
4 seT
30 reps
25 reps
20 reps
15 reps
30% of 1RM
40% of 1RM
50% of 1RM
65% of 1RM
30-60 seconds
30-60 seconds
30-60 seconds
30-60 seconds
Triceps
As with biceps exercises, you can use any isolation triceps exercise and apply BFR to that
exercise. However, let's look at a few examples of exercises, sets and reps to work the triceps with
BFR.
ELBOW EXTENSIONS WITH ROPE AND BFR
SeTs
Reps
% of 1RM
Rest
1 seT
20 reps
50% of 1RM
30-60 seconds
2 seT
20 reps
50% of 1RM
30-60 seconds
3 seT
20 reps
50% of 1RM
30-60 seconds
4 seT
20 reps
50% de 1RM
30-60 seconds
SeTs
1 seT
2 seT
3 set
4 seT
TRICEPS DIPS WITH BFR
Reps
% of 1RM
Rest
30 reps
30% of 1RM
30-60 seconds
25 reps
40% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
15 reps
65% of 1RM
30-60 seconds
OVERHEAD ELBOW EXTENSIONS AND BFR
SeTS
Reps
% of 1RM
Rest
1 seT
30 reps
30% of 1RM
30-60 seconds
2 seT
25 reps
40% of 1RM
30-60 seconds
3 seT
20 reps
50% of 1RM
30-60 seconds
4 seT
20 reps
50% of 1RM
30-60 seconds
Forearms
For forearm training the recommendations are that the BFR bands are placed in the same place
as when training biceps or triceps, that is, just below the deltoid.
BFR training can be applied to all forearm exercises, but we are going to look at 2 of the most
effective and which have demonstrated the greatest potential for muscle growth when performed with
BFR.
FOREARM CURL WITH BAR AND BFR
SeTS
Reps
% of 1RM
Rest
1 seT
20 reps
50% of 1RM
30 seconds
2 seT
20 reps
50% of 1RM
30 seconds
3 seT
20 reps
50% of 1RM
30 seconds
4 seT
20 reps
50% of 1RM
30 seconds
REVERSE FOREARM CURL WITH BAR AND BFR
SeTs
Reps
% of 1RM
Rest
1 seT
30 reps
30% of 1RM
30 seconds
2 seT
25 reps
40% of 1RM
30 seconds
3 seT
20 reps
50% of 1RM
30 seconds
4 seT
20 reps
50% of 1RM
30 seconds
In forearms, short rests between sets are recommended. But when moving from one exercise to
the next you can loosen the bands and rest for one minute between the two exercises.
Quadriceps
Next, we will look at some exercises that primarily involve the quadriceps. Obviously, you can use
many more if you wish and those that allow you can also do them unilaterally.
MACHINE KNEE EXTENSIONS WITH BFR
SeTS
Reps
% of 1RM
Rest
1 seT
30 reps
30% of 1RM
30-60 seconds
2 seT
25 reps
40% of 1RM
30-60 seconds
3 seT
20 reps
50% of 1RM
30-60 seconds
4 seT
20 reps
50% of 1RM
30-60 seconds
SeTS
1 seT
2 seT
3 seT
4 seT
LEG PRESS WITH BFR
Reps
% of 1RM
30 reps
30% of 1RM
25 reps
40% of 1RM
20 reps
50% of 1RM
15 reps
65% of 1RM
SeTs
1 seT
2 seT
3 set
4 seT
GLOBET SQUAT WITH BFR
Reps
% of 1RM
Rest
30 reps
30% of 1RM
30-60 seconds
25 reps
40% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
SeTS
1 seT
2 seT
3 seT
4 seT
SISSY SQUAT WITH BFR
Reps
% of 1RM
Rest
30 reps
30% of 1RM
30-60 seconds
25 reps
40% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
Rest
60 seconds
60 seconds
60 seconds
60 seconds
MULTIPOWER SQUAT OR FREE SQUAT WITH BFR
SeTS
Reps
% of 1RM
Rest
1 seT
30 reps
30% of 1RM
60 seconds
2 seT
25 reps
40% of 1RM
60 seconds
3 seT
20 reps
50% of 1RM
60 seconds
4 seT
15 reps
65% of 1RM
60 seconds
Hamstrings
The hamstrings are activated with any multi-joint exercise that involves the legs. But when we
work with BFR what we are looking for is maximum activation of the target muscle, so we are going to
look at some exercises that primarily stimulate the hamstrings.
Hamstrings SEATED ON MACHINE WITH BFR
SeTs
Reps
% of 1RM
Rest
1 seT
20 reps
50% of 1RM
30-60 seconds
2 seT
20 reps
50% de 1RM
30-60 seconds
3 seT
20 reps
50% de 1RM
30-60 seconds
4 seT
20 reps
50% de 1RM
30-60 seconds
Hamstrings LYING ON MACHINE WITH BFR
SeTs
Reps
% of 1RM
Rest
1 seT
30 reps
30% of 1RM
30-60 seconds
2 seT
25 reps
40% of 1RM
30-60 seconds
3 seT
20 reps
50% of 1RM
30-60 seconds
4 seT
20 reps
50% of 1RM
30-60 seconds
SeTs
1 seT
2 seT
3 seT
4 seT
NORDIC CURL WITH BFR
Reps
% of 1RM
Rest
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
Calves
The calves are extremely complicated muscles to grow. The soleus is composed mostly of red
fibers that are much more reluctant to grow with regular hypertrophy training.
However, with BFR you get an increase in the slow twitch fibers (the red type I fibers), so in the
case of the calves it’s especially useful and improvements are obtained in record time when trained
correctly and with BFR.
SeTs
1 set
2 seT
3 seT
4 seT
STANDING HEEL LIFTS WITH BFR
Reps
% of 1RM
Rest
30 reps
30% of 1RM
30-60 seconds
25 reps
40% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
SeTs
1 seT
2 seT
3 seT
4 seT
SEATED HEEL RAISES WITH BFR
Reps
% of 1RM
Rest
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
SeTs
1 seT
2 seT
3 seT
4 seT
HEEL LIFTS IN PRESS WITH BFR
Reps
% of 1RM
Rest
30 reps
30% of 1RM
30-60 seconds
25 reps
40% of 1RM
30-60 seconds
20 reps
50% of 1RM
30-60 seconds
15 reps
65% of 1RM
30-60 seconds
BFR training on muscles not receiving BFR
In the chapter "Effects on the musculature without BFR", we have seen that with BFRT
improvements can be obtained in groups where BFR is not directly applied, such as the chest, back or
shoulders.
However, performing exercises to improve these groups doesn’t follow very specific protocols. it’s
simply a matter of performing an exercise involving, for example, the chest as a horizontal push-up at
a hypertrophy rep range (12-20 reps) and applying BFR on the arms.
And the same would be true if we wanted to use BFR for improvements in latissimus dorsi work,
we would simply perform a horizontal or vertical pull exercise at a range of 12-20 repetitions using
BFR on the arms.
For more information on the mechanisms and the way BFR on the extremities can help improve a
muscle that doesn’t have BFR directly applied, see the chapter "Effects on Musculature without BFR".
SUPPLEMENTATION AND TRAINING WITH BFR
Recommended or useful supplementation with BFR training
We know that the main mechanisms by which we can obtain hypertrophy are mechanical tension,
muscle damage (necessary for signaling, but better if it is reduced), and metabolic stress [162].
With BFR training we manage to increase the three main mechanisms by which hypertrophy is
obtained minus muscle damage, which according to several interventions, the muscle damage that
occurs with BFRT and light loads is less than that which occurs with loads of 70% of 1RM or more.
The fact is that, with BFRT, in addition to obtaining the same adaptations as training without BFR,
we obtain a set of additional adaptations that we have already seen in previous chapters and that only
occur, or at least are much more potentiated in a state of hypoxia.
One that occurs with BFR training is cellular swelling.
Since cellular swelling is much higher in a state of hypoxia, it’s one points that we could look at
when assessing what type of supplementation, we could use during BFR training.
We are going to review very briefly why this cellular swelling or muscular congestion occurs.
We have that, during the training with loads, the blood flow that arrives from the arteries to the
muscles that are contracting increases to be able to nourish the muscle with oxygen and nutrients,
with which, the muscle fills more and more with blood, but the use of bands causes a restriction of the
venous return due, and this causes that the capacity of the muscle in accumulating blood begins to be
overwhelmed.
To understand this, we can imagine that we fill a balloon with water, the balloon fills up and as
there is nowhere for the water to come out, the balloon continues to fill up and get bigger and bigger.
Although you can later empty the balloon, after having exceeded its capacity, it will not recover its
initial size, it will always remain somewhat larger than before due to the stretching of its structure that
caused the entry of excess water.
Let us say that something similar happens in the muscles. More and more blood flow is pumped
into the muscle as long as the muscle contractions don’t stop occurring, as the venous return is
restricted, a "build-up" of blood is created in the muscle together with a large cellular swelling, which
causes this pumping and muscular congestion that can even be painful in some cases.
The body perceives this sudden swelling as a threat to the structural integrity of the cell and its
survival. In response to this threat, the cell performs several anabolic processes (including upregulation of protein synthesis [87] while also down-regulating various catabolic processes in addition
to a decrease in myostatin [54]. All this to make a larger, stronger, and more resistant muscle cell [61]
in order to prepare for future aggressions.
In a 2017 review Freitas [63] already suggested that metabolic stress seems to play a key role in
hypertrophy. While it’s true that the mechanisms by which hypertrophy is produced by increased
metabolite accumulation are still unclear, the relationship between metabolic stress and hypertrophy is
clear, especially under conditions of hypoxia.
The role of metabolic stress according to Freitas et al. 2017 [63].
If we consider that one of the advantages of training with BFR is to achieve a greater
accumulation of metabolic stress and greater cellular swelling, among other things. It would be
plausible to think that the more metabolic stress, the more cellular swelling, the more pumping and
blood inflow to the muscle during workouts, the better the hypertrophy results might be.
Therefore, when selecting specific supplementation with BFR training we could try to enhance
cellular swelling and blood influx to maximize the effects we intend to enhance with BFRT.
Precisely the review by Cholewa et al. in 2019 [163] focused on elucidating which types of
supplements would be the most indicated to improve muscle swelling and reviewed the efficacy of
some supplements such as creatine, beta alanine or citrulline malate. Precisely these 3
supplements are for me the basic ones, which I use and recommend improving performance.
Supplements such as creatine, beta alanine, and citrulline malate have been shown to be useful
separately in various studies, they would be supplements that could help both training with BFR and
training without BFR, but in this chapter we will look at some of the supplements that might be
interesting when training with BFR and why.
The order of the supplements that we will see next is not necessarily the order of priority, and the
supplementation that we will see next and can be used with BFR can be perfectly applied in a
conventional hypertrophy training. It’s true that some supplements such as ALCAR are particularly
useful in a state of hypoxia.
Creatine Monohydrate
Creatine needs no introduction, it’s one of the most studied supplements and its efficacy and
safety have been amply demonstrated.
It presents a wide range of benefits not only in terms of sports performance and strength, but in
order not to have to go into other details that are beyond the scope of this book we are going to talk
mainly about the improvements that we can obtain from its consumption when we are performing
workouts in which we also include BFR.
Something we already know is that creatine improves ATP production by increasing the creatine
phosphate reserves in skeletal muscle. Therefore, this means an improvement in performance in all
those physical performances that demand high intensity.
But, in addition to the improvement in ATP production, we have a number of advantages that
make creatine an interesting supplement when we train in a state of hypoxia (with blood flow
restriction).
Creatine can also improve vasodilation. In fact, some research indicates that creatine
monohydrate supplementation decreases arterial stiffness and systolic blood pressure after strength
training [164]. It has also demonstrated improvements in systemic endothelium-dependent
microvascular reactivity, suggesting that it has vasodilatory properties [165].
Creatine also directly improves cellular hydration due to its osmotic qualities. With increased
intramuscular creatine stores, there is an increase in the amount of water stored within the cell. This
leads to greater cell volume expansion, improved hydration, and increased muscle fullness.
Since one of the things, we are looking for with BFRT is cellular swelling and creatine also
produces improvements in that regard, so we have yet another reason to add it to our BFR training.
Two other interesting mechanisms by which creatine might enhance muscle growth would be by
up-regulation of mRNA encoding IGF-1 and myogenic regulatory factor 4 (MRF4) mRNA expression
[166][167].
Como vemos la creatina puede potenciar los efectos de la BFR mediante varios mecanismos,
entre los que se incluyen una mayor hinchazón celular, una regulación al alza de la síntesis de
proteína muscular, un aumento en la capacidad de trabajo y fuerza, y muy probablemente también
una mayor vasodilatación.
Thanks to these mechanisms, it would be possible to perform a few more repetitions, which would
produce a greater accumulation of metabolites, greater cellular swelling and, in short, a greater
potentiation of the effects that we are looking for with BFR training.
Instructions for use and creatine dosage
There are many protocols for creatine intake, and all can be valid. The protocol I recommend is
between 0.7g and 1g per 10kg of body weight taking creatine only on training days. This means that a
80kg person could take between 5.6g and 8g of creatine, but only on training days, with no loading
phase or rest periods.
With creatine there are many ways to take it and many protocols, basically is to use the most
comfortable for you. It can be taken indefinitely only on training days or take 5g every day and every
3/6 months take a short break of a few weeks, although it can also be continued for much longer
because at that dose it has been shown to be a safe supplement in studies of up to several years
[168][169].
The protocols of use are very varied and to explain in excess all the possibilities would take us an
entire chapter, I generally recommend a dose of 5g to 8g on training days and on rest days not to take
anything, basically for convenience and to be able to forget the intake of creatine and other
supplements on non-training days.
For more details on how to take creatine you can visit my blog at www.tonilloret.club or my
YouTube channel where I talk about creatine more extensively and how to combine it with other
supplements such as beta alanine for performance improvements.
Beta Alanine
Beta alanine increases carnosine levels, and carnosine stimulates nitric oxide levels. Since
increases in nitric oxide levels aid in cellular swelling as reviewed by Cholewa et al [163], it might be of
interest to include beta alanine in our supplementation.
When we perform BFR training, beta alanine provides an extra benefit. It is known that with blood
flow restriction training especially at high occlusion levels (about 80%) is a potential cause of
neuromuscular fatigue syndrome, which is related to hypoxia [170] and neurotransmitter dysfunction
[171].
And it is also known about the antioxidant capacity of elevated carnosine levels in muscle tissue,
and that elevated carnosine levels could exert protective effects on neuromuscular fatigue [172].
Therefore, in the case of BFR training beta alanine would play a more specific performance-enhancing
role in BFR training by preventing a certain degree of neuromuscular fatigue that can occur with BFR
training.
Instructions for use and beta alanine dosage
The general recommendations for the use of beta alanine is to use doses of 6.4g and to spread
the dose over 4 intakes of 1.6g, spacing the intakes between 3 and 4 hours apart [173]. The reason
for spacing the doses is to avoid a possible side effect called paresthesia that usually occurs with
acute and high doses of beta alanine, which is basically a tingling or itching of the skin that, although it
can be annoying, is completely harmless.
However, with beta alanine, different protocols of use can also be employed. If you like to go the
extra mile, you can use a loading phase of several weeks and then continue with a maintenance
phase afterwards.
I talk more extensively about the different protocols of use of beta alanine in a YouTube video,
but, and for the sake of simplicity and effectiveness, the protocol I use and recommend is to take 0.7g
and 1g per 10Kg of weight only on training days. That means that an 80kg person could take between
5.6g and 8g of beta alanine on training days and rest from its use on non-training days.
In case a high dose causes paresthesia, and you find it bothersome, you can divide the dose
throughout the day and spread it over several doses (4-8 doses) and take it preferably with meals to
avoid paresthesia as much as possible. Paresthesia is a tingling or itching that usually accompanies
beta alanine intakes but is completely harmless.
Betaine
Betaine (also known as trimethyl glycine TMG), is a modified amino acid consisting of a glycine
molecule surrounded by three methyl groups.
It occurs naturally in the human body and can be found in various foods such as spinach, wheat,
and beets.
Betaine plays an essential role in the cardiovascular system health. Betaine, along with other
nutrients such as folic acid, vitamin B6 and B12, helps to reduce homocysteine levels.
High homocysteine levels are associated with serious cardiovascular and neurological diseases.
Excess homocysteine can cause damage to blood vessel walls. This can lead to atherosclerosis due
to plaque build-up and stiffening of the arteries, heart failure and consequently heart and brain
infarctions.
As for its benefits in increasing muscular strength and endurance, according to some studies it
may help to improve sports performance [174][175][176][177].
But as Ahmed Ismaeel [178] points out in his systematic review with meta-analysis, although an
improvement is indeed seen in some studies in the betaine group, more research is needed to
determine whether betaine alone improves athletic performance.
However, betaine has two important functions in the body as a methyl group donor and as an
osmotic regulator of cell water balance [177]. That betaine can regulate the water balance of the cell is
of particular importance when training with BFR since excessive cell swelling could cause the cell to
die by swelling to the point of bursting.
Betaine acts by better preserving the cell structure and making it more resistant to the stress it
receives, so it could be interesting to include it in our combo.
Obviously more specific research will be needed with athletes taking betaine and training for
hypertrophy and strength improvements with BFR, but until that happens (if it does), for the reasons I
have stated above it seems to me that it might be interesting to include it in a specific BFR
supplementation protocol.
In addition, it seems that it can increase the anabolic response (GH, IGF-1 and SPM) after
exercise [179], so if the effect on these increases is in addition to that already achieved with BFRT, the
inclusion of betaine in our supplementation arsenal could be very interesting.
Despite its multiple benefits, betaine also has a less friendly side, and that is that it could present
some mild side effects such as, for example, stomach discomfort or nausea. In case of noticing any
kind of side effect in that sense, the dose should be reduced, or the supplementation should be
withdrawn.
If you are taking any type of medication, you should consult your doctor before taking betaine.
Instructions for use and betaine dosage
The effective dose for sports performance enhancement is between 3g and 5g divided into 2
intakes per day and can be taken at any time of the day.
Electrolytes
Another avenue by which we can maximize cellular hydration and swelling would be through the
addition of electrolytes. Electrolytes are essential minerals that help regulate fluid balance in the body
as well as muscle function.
Sodium often gets most of the credit when talking about electrolytes, but there are two other
equally important electrolytes, potassium, and magnesium.
These two vital minerals serve as osmoprotectants when used in conjunction with other
prominent supplements that hydrate cells, such as betaine and creatine monohydrate.
Electrolytes help preserve intracellular fluid balance, balance the body's acid/base (pH) level and
transport nutrients into your cells. As well as eliminate waste from the cells.
The main electrolytes involved in physical activity are these:
Sodium, is more abundant in the extracellular fluid. It’s involved in the control of blood
pressure as well as promoting muscle contraction.
Potassium, it’s the main responsible for glycogen storage and for maintaining water balance.
Magnesium, its main function is the activation of vitamins and enzymes, as well as the
acceleration of protein
Calcium, mainly responsible for the transmission of nerve impulses and the activation of
nerves and muscles. Muscle contraction depends on this mineral.
Chloride, regulates the amount of liquid in the organism and to maintain the acid-base
balance. Chloride is present in all body fluids, but is found in higher concentration in the
blood and extracellular fluid.
Instructions for use of electrolytes
There is a wide variety of presentations in electrolyte supplements, and they don’t necessarily
contain all the same electrolytes. Therefore, the form in which they are to be taken may vary between
different brands. The most sensible thing to do is to follow the instructions for use indicated on the
package, since each supplement may have a different composition and may even have other
supplements added, such as caffeine or carbohydrates.
L-CARNITINE AND BFR TRAINING
When we analyzed beta alanine and its role in BFR training, we discussed its ability to exert
protective effects on the part of neuromuscular fatigue that is directly related to hypoxia[170] thanks to
increased muscle carnosine levels [172].
L-carnitine shows several properties like carnosine, therefore, it could fulfill the same function and
be the perfect complement to beta alanine in order to reduce neuromuscular fatigue that occurs in a
state of hypoxia.
Supplementation with L-carnitine has been shown in different studies to exert favorable effects on
cellular energy metabolism and on the processes involved in skeletal muscle remodeling [180] [181]
[182]. But in addition to the most well-known benefits, what really interests us about L-carnitine when
training with BFR is its ability to reduce the biochemical alterations that occur in a state of hypoxia
[181] [183].
Higher serum concentrations of L-carnitine increase L-carnitine transport through skeletal muscle
and the neuromuscular junction. It is this effect that could reduce some of the alterations resulting from
hypoxia and stimulate acetylcholine synthesis. In fact, data from early studies suggest that the athletic
population may benefit from L-carnitine intake precisely because of the increase in blood flow and
oxygen supply to muscle tissue, thereby reducing the negative alterations at the neuromuscular level
related to hypoxia [181].
On the benefits offered by L-carnitine due to increases in blood flow and oxygen supply we have
several investigations, such as that of Karlic and Lohninger [184], in which they saw that
supplementation with L-carnitine reduced the hypoxic damage caused by high-intensity training and
exerted a favorable effect by accelerating recovery from exercise stress.
L-carnitine supplementation is also showing promise for the improvement of neuronal
functionality. Since the main ester of L-carnitine, acetyl L-carnitine (ALC), has been shown to exert
neuroprotective and neurotrophic effects on the nervous system and optimize neutrophin signaling by
enhancing energy supply and neuronal responses [180][185].
Acetyl L-carnitine (ALC) has been shown in rodents to enhance neuroprotective properties by
facilitating neurotransmitter biosynthesis in the brain [186].
This occurs because acetyl coenzyme A derived from acetyl L-carnitine (ALC), serves as an
alternative substrate for brain acetylcholine synthesis [187]. Therefore, L-carnitine supplementation
could be a good strategy to reduce hypoxia-related neural fatigue that occurs with BFR training.
Why does BFR training promote hypoxia?
When the oxygen supply to the bloodstream doesn’t meet the demands of the tissue cells, what’s
called a state of hypoxia occurs [188]. What we seek with blood flow restriction is to restrict venous
return and allow blood inflow. But inevitably, by restricting venous return there is always going to be
some degree of occlusion in the inflow of blood from the arteries, and therefore, there will be a
deficiency of available oxygen to the cells (hypoxia).
In fact, increases in serum lactate levels that occur with anaerobic metabolism are a clear
indication of hypoxic stress. As early as 2005, the team of Sato et al [189], obtained direct evidence
that significant increases in lactate levels occur during BFR training in response to hypoxia.
Neuromuscular fatigue and hypoxia
The first thing to keep in mind is that neuromuscular fatigue can be caused by central or
peripheral mechanisms [190].
Central fatigue is primarily a reduction in the ability of the CNS to activate muscles [191].
What we call peripheral neuromuscular fatigue is due to the impairment of mechanisms ranging
from excitation to muscle contraction, which results in a loss of the ability to generate force, and this
peripheral neuromuscular fatigue is mainly caused by a sets of metabolic events occurring within the
muscle [192][193][194][195][196].
BFR training increases neural activation due to the hypoxia condition and this will be higher or
lower depending on the degree of hypoxia generated by BFR training, as verified by Pedro Fatela et
al. in 2016 [144].
Fatela's team found that even with loads as low as 20% of 1RM BFR training resulted in
neuromuscular fatigue when vascular restriction was 80%. In Fatela's trial they found that
neuromuscular activation varied as a function of the pressure exerted during BFR training. The higher
the occlusion pressure, the greater the neuromuscular fatigue.
Therefore, it’s not at all advisable to exceed occlusion levels of 80% since, among other things,
this leads to greater neuromuscular fatigue, and it would also be necessary to check whether a longer
duration of BFR sessions, even with lower occlusion levels, would also cause significant increases in
neuromuscular fatigue. What is clear is that the more pressure at the vascular occlusion level (VOL),
the more neuromuscular fatigue [144]. However, in terms of adaptations there seems to be no
difference between using pressures of 30-40% versus pressures of 80-90% if loads of more than 30%
of the 1RM are used [143]. Thus, exceeding the pressure level doesn’t seem to confer additional
benefits but rather the opposite.
Generally, the levels of hypoxia caused with BFRT are moderate levels of hypoxia. Hypoxia levels
related to neuromuscular fatigue could be divided into three groups, mild, moderate, and severe [170].
And the neuromuscular fatigue produced by BFRT would fall into the group of moderate hypoxia
levels.
This neuromuscular fatigue is produced by a combination of peripheral components due to
decreases in muscle contractions, and central components due to decreases in the percentage of
vascular restriction and amplitude of electromyography, as noted by Broxterman et al [197].
Although the levels of hypoxia with BFRT are moderate, it is postulated that neuromuscular
excitability could be compromised, thus generating some central and peripheral fatigue. In any case,
to date, researchers haven’t reached a consensus as to whether it’s largely a peripheral or central
component that plays the key role in the neuromuscular fatigue associated with BFR training.
Acetylcholine, neuromuscular fatigue, and L-carnitine
L-carnitine mediates adaptation to hypoxia induced by BFR training through increased
mitochondrial consumption.
The hypoxia that occurs with BFR triggers neuromuscular fatigue (peripheral and central), and
this neuromuscular fatigue in turn triggers inadequate release of acetylcholine, which is associated
with neuromuscular fatigue [198]. It’s here that L-carnitine plays a very important modulatory role in
the indirect transport of acetyl groups that favor acetylcholine synthesis, thus attenuating
neuromuscular fatigue.
Graphical representation of how L-carnitine promotes increased oxygen to the cell and
acetylcholine synthesis according to Shen et al. (2020) [199].
L-carnitine ameliorates both hypoxic stress and neuromuscular transmission failure by stimulating
TCA or Krebs cycle activity and increasing acetylcholine synthesis. Since acetyl coenzyme A derived
from acetyl L-carnitine (which is the main acetyl ester of L-carnitine), it serves not only as an
oxidizable substrate of the TCA cycle, but also as an alternative and promising substrate for
acetylcholine synthesis.
L-carnitine promotes acetylcholine synthesis [199].
Metabolic adaptation to hypoxia produced by BFRT involves the modification of the TCA cycle
(Krebs cycle) by the shunting of pyruvate to lactate. These processes cause an alteration of ATP
formation in the glucose to pyruvate pathway, thereby resulting in the accumulation of metabolic byproducts (especially lactate) that are closely associated with BFR training.
Benefits of L-carnitine on hypoxic stress
There are a large number of studies in rodents in which L-carnitine has been found to be useful in
reducing both stress and muscle fatigue and brain damage caused by hypoxia [200] [201][202][203]
[204].
In view of the results seen in rodents Kraemer et al. conducted several human trials [205][206]
[207] whose results show that L-carnitine intake exerts a favorable effect in attenuating exerciseinduced hypoxic damage.
Therefore, it’s entirely plausible to think that with the use of L-carnitine we will be able to reduce
part of the neuromuscular fatigue produced by hypoxic stress due to BFR training.
The role of serum L-carnitine in biological functions
Oral supplementation with L-carnitine in healthy subjects has been shown to increase plasma
carnitine levels [208] significantly compared to normal levels.
Increases in serum L-carnitine levels exert effects on metabolism, including increased blood flow
and oxygen delivery to muscle tissue [181], in addition to a positive effect on post-exercise recovery
that is mediated by increased excretion of free and esterified carnitine [209]. Such an increase favors
the attenuation of muscle soreness and hypoxia-induced metabolic stress [181][183].
As we have seen L-carnitine is not so useless after all and serum L-carnitine concentrations play
an even more relevant role in a state of hypoxia.
There are several mechanisms by which L-carnitine plays a relevant role in BFR training
conditions.
1.
Increases mitochondrial oxygen consumption, thus attenuating the negative effects of
neuromuscular fatigue induced by hypoxia training.
2.
L-carnitine mediates the accumulation of metabolic by-products that occur during BFR
training. Specifically, it reduces the concentration of inorganic phosphate protons (Pi) and
lactic acid concentration in the brain, as well as decreases mitochondrial pyruvate content,
plasma lactate level, and helps maintain a favorable acetyl coenzyme A ratio, which is key to
energy metabolism [184][210][211].
3.
Increases ATP production since it is involved in the role of beta-oxidation of free fatty acids
causing them to move across the inner membrane of cells to be processed for energy (ATP)
[212].
4.
Attenuates neuromuscular fatigue. L-carnitine has the ability to cross the blood-brain barrier
[213][214][215] (especially acetyl L-carnitine) and thus enhance acetylcholine synthesis,
resulting in reductions in neuromuscular fatigue. We know that acetylcholine release and
depletion from nerve terminals is associated with neuromuscular fatigue [196][216][216][217].
This strongly suggests that L-carnitine supplementation during BFRT exerts effects on
ameliorating neuromuscular fatigue by modulating the acetylation state through an increase
in acetyl-CoA content that at the same time increases acetylcholine production in the brain.
Instructions for use and L-carnitine dosage
After what we have seen about the role of L-carnitine especially in hypoxic conditions, L-carnitine
supplementation would be recommended with BFR training and highly recommended especially in
these two scenarios.
1.
When we start with BFR training.
2.
When we are in a more advanced stage, either because we apply BFR for longer, apply more
intensity or use advanced techniques. In these cases, it would be interesting to supplement
with L-carnitine.
Obviously, L-carnitine can be used in many other scenarios, but for the sake of simplification and
to stay within the subject of the book, I will limit myself to cite two possible scenarios related to the
BFRT.
Protocol of use
3g of oral L-carnitine about 30/60 minutes prior to training.
1g of Acetyl L-carnitine (ALC) about 30/60 minutes before training.
Doses of L-carnitine can vary and can be taken at different times of the day.
Another type of intake that I personally like to take would be 1g of Acetyl L-carnitine in the morning
for cognitive performance enhancement and another gram of ALCAR (acetyl l-carnitine) 30/60 minutes
before training along with the pure L-carnitine and the rest of the pre-workout supplementation if used.
L-carnitine can be mixed with the rest of the supplementation. In case you only want to use one Lcarnitine, it’s probably more interesting to use acetyl l-carnitine, and in case of using it alone I would
use 1g of ALCAR in the morning and another gram 30/60 minutes before the training session.
L-carnitine is not a supplement that usually causes stomach or gastrointestinal problems, but if
you notice discomfort in this regard or even nausea, it’s advisable to discontinue supplementation.
Although as I say, l-carnitine is not usually the cause of this type of discomfort, so in the case of
taking it together with other supplements, it would be necessary to take the supplementation in
isolation (every day one) to detect which supplement could be the cause of some type of
gastrointestinal problem.
Other supplements such as creatine have been shown to cause such problems more frequently,
especially when it contains impurities or is taken at very high doses, in which case, it would be best to
divide the dose of creatine in two doses [218].
CONCLUSIONS
First, I would like to thank you for having made it this far. I sincerely hope that you found the book
interesting and that you learned new things from it.
A lot of things are said about BFR Training and most of the opinions are rooted in past beliefs
without having a solid and real knowledge base about what BFR training is and how it should be
applied in advanced strength athletes.
I hope I have shed some light on that aspect and helped you to better understand what BFR
training is and how it works. Once you have all the facts you can decide whether it’s worthwhile (or
not) to incorporate it into your strength or hypertrophy training.
I think that with all the evidence we have when the goal of training is hypertrophy gains it’s absurd
not to take advantage of the benefits that can be obtained by just adding 10 minutes of BFR in a
training session. But to each his own...
Vertical hammer press with 160 Kg
for 18/20 repetitions (advanced BFRT)
BFR training and advanced protocols
One thing to understand is that in BFR training we don’t have any studies in which advanced
protocols are applied, for example, BFR in drop sets, with loads of 70% of 1RM or more, or much
longer times of use with BFR.
Since we don’t have evidence to support the safety of such protocols, I haven’t mentioned them in
the book and have limited myself to the protocols recommended by researchers that have been
shown to be safe and useful.
Horizontal hammer press with 200
Kg for 12/15 repetitions (advanced BFRT)
Final recommendations
This book has been written with the idea of breaking the clichés and the general lack of
knowledge about BFR training, so that anyone can understand the basics and can benefit from
applying BFR in their training. I have tried to make this book practical, didactic, and based on the
evidence we have about BFR training.
BFR training protocols in the book are those recommended by researchers. They are protocols
that have been extensively studied. However, advanced users could employ much more advanced
BFRT protocols. One could use loads of more than 50% of 1RM, longer time periods with BFR,
advanced training techniques with BFR, etc. But I haven’t included such advanced protocols in the
book because, although we do have empirical evidence from hundreds of people who are using them
with good results, the truth is that so far there is no scientific evidence about their safety.
The use of advanced training protocols is also not necessary and should mostly be reserved for
users with a lot of experience with the BFRT. In fact, if you start implementing the basic protocols, we
have seen in the book you will get good results. In fact, they are the protocols that everyone should
start with when using BFRT. And remember that, if you have any questions you have at your disposal
the telegram group, where you can ask any questions about the BFRT or share your results with
dozens of people who are already training with BFR for a long time and getting good results with both
basic and advanced protocols.
Once again, thank you very much for your confidence in my work and I hope you found the reading
interesting. But above all, I hope you take action and if you don’t have any contraindications, apply the
BFR protocols that we have seen in the book and that will undoubtedly help you to improve your
hypertrophy and strength.
Toni Lloret
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About The Author
Toni Lloret
My name is Toni Lloret, I have been training and studying everything re-lated to training for muscle
mass gains and strength improvement for al-most 20 years, and for the last 10 years I have been
exclusively dedicated to advising both competitive bodybuilders and people who simply want to
improve their physique, either by increasing muscle mass, losing fat and ultimately achieve a more
athletic and muscular physique.
I am passionate about everything related to weight training with the aim of increasing muscle mass
and everything that is related to it (nutrition, train-ing, supplementation, physiology, etc.).
SPORTING AWARDS
I am one of those who think that it’s not enough to have the knowledge, you also must know how to
put it into practice. So, for a few years I was competing in bodybuilding until mid-2018 I left the
competition be-cause of an abdominal hernia that had been dragging for years and had grown so
much that subtracted many points in competition, because aesthetically it was an important defect.
Even with that defect I managed to win half of the competitions I entered.
Year 2018: 1st Classified Mr. Olympia Amateur Spain - Master Heavy Weight Bodybuilding
Year 2018: 6th Classified Mr. Olympia Amateur Spain - Super Heavy Weight Bodybuilding Senior
Year 2018: 1st Classified National Open Iron Baby- FNFF
Year 2018: 1st Classified and Absolute Champion Copa de Valencia FNFF
Year 2018: 1st Classified and Absolute Champion Master Bodybuilding at the Spanish Championship IBFF
Year 2018: 1st Classified National Open Laura Guillen- FNFF
Year 2017: 3rd Classified - Arnold Classic Amateur (Master Bodybuilding 40/44 +90Kg) - IFBB
Year 2017: 1st Classified - IV Open National Trophy City of Castellón (Mas-ter Bodybuilding) - IFBB
Year 2017: 5th Classified - XIV National Open Pedro J. Villa (Senior Body-building) - IFBB
Year 2017: 1st Classified and Absolute Champion Master Bodybuilding in the Spanish National Cup. IFBB
Year 2017: 2nd Classified - III Verónica Gallego (Senior Bodybuilding Open type) - IFBB
Year 2016: 3rd Classified - III Open National Trophy City of Castellón (Bodybuilding Master) - IFBB
Year 2016: 2nd Classified - I Championship Feria de Albacete FCMFF 2016 (Senior Bodybuilding) IFBB
Year 2016: 3rd Classified - Iron Baby Championship (Senior Bodybuilding) - IFBB
Year 2016: 1st Classified - XIII National Open Pedro J. Villa (Master Body-building) - IFBB
Year 2016: 1st Classified - II Championship Vamos A+ Yecla (Master and Absolute Bodybuilding) IFBB
Year 2016: 3rd Classified - II National Open Veronica Gallego (Senior Heavyweight) - IFBB
Year 2016: 1st Classified - II Valencia Cup (Master Bodybuilding) - IFBB
Year 2016: 1st Classified - IV Championship Trophy All with Natalia (Mas-ter and Absolute
Bodybuilding) - IFBB
Year 2015: 1st Classified - XXVI Spanish Championship of Strength and Endurance in Bench Press
2016, Master I Category.
Year 2015: 5th Classified - XLVII Spanish Championship (Classic Body-building Master) - IFBB
Year 2015: 5th Classified - XII Open National Trophy Memorial Eusebio Esteban (Classic
Bodybuilding) - IFBB
Year 2015: 3rd Classified - Championship Comunidad Valenciana (Classic BodyBuilding Tall Size) IFBB
Year 2015: 1st Classified - III Trophy Villa de Onil 2015 (Classic Body-Building Tall Size) - IFBB
Year 2015: 2nd Classified - I National Championship Vamos A+ Santomera (Classic BodyBuilding
High Size) - IFBB
Year 2015: 1st Classified - Trophy City of Castellón (Classic Bodybuilding) - IFBB
Year 2015: 6th Classified - II Open National Trophy City of Castellón (Clas-sic Bodybuilding) - IFBB
Year 2015: 5th Classified - XII National Open Pedro J Villa (Classic Body-building) - IFBB
Year 2014: 2nd Classified - XXV Spanish Championship of Strength and Endurance in Bench Press,
Master I Category.
Year 2013: 1st Classified - XXV Spanish Championship of Strength and Endurance in Bench Press,
Master I Category