PTJ: Physical Therapy & Rehabilitation Journal | Physical Therapy, 2021;101:1–9
https://doi.org/10.1093/ptj/pzab172
Advance access publication date July 6, 2021
Perspective
Robert Bielitzki, MA1 ,* , Tom Behrendt, MA1 , Martin Behrens, PhD1 ,2 , Lutz Schega, PhD1
1 Department
2 Department
of Sport Science, Institute III, Otto von Guericke University Magdeburg, Magdeburg, Germany
of Orthopedics, University Medicine Rostock, Rostock, Germany
*Address all correspondence to Mr Bielitzki at: robert.bielitzki@ovgu.de
Abstract
The main goal of musculoskeletal rehabilitation is to achieve the pre-injury and/or pre-surgery physical function level with
a low risk of re-injury. Blood flow restriction (BFR) training is a promising alternative to conventional therapy approaches
during musculoskeletal rehabilitation because various studies support its beneficial effects on muscle mass, strength, aerobic
capacity, and pain perception. In this perspective article, we used an evidence-based progressive model of a rehabilitative
program that integrated BFR in 4 rehabilitation phases: (1) passive BFR, (2) BFR combined with aerobic training, (3) BFR
combined with low-load resistance training, and (4) BFR combined with low-load resistance training and traditional highload resistance training. Considering the current research, we propose that a BFR-assisted rehabilitation has the potential
to shorten the time course of therapy to reach the stage where the patient is able to tolerate resistance training with high
loads. The information and arguments presented are intended to stimulate future research, which compares the time to
achieve rehabilitative milestones and their physiological bases in each stage of the musculoskeletal rehabilitation process.
This requires the quantification of BFR training-induced adaptations (eg, muscle mass, strength, capillary-to-muscle-area ratio,
hypoalgesia, molecular changes) and the associated changes in performance with a high measurement frequency (≤1 week)
to test our hypothesis. This information will help to quantify the time saved by BFR-assisted musculoskeletal rehabilitation.
This is of particular importance for patients, because the potentially accelerated recovery of physical functioning would allow
them to return to their work and/or social life earlier. Furthermore, other stakeholders in the health care system (eg, physicians,
nurses, physical therapists, insurance companies) might benefit from that with regard to work and financial burden.
Keywords: Injury, Occlusion Training, Surgery, Vascular Occlusion
Received: December 11, 2020. Revised: April 14, 2021. Accepted: June 6, 2021
© The Author(s) 2021. Published by Oxford University Press on behalf of the American Physical Therapy Association. All rights reserved.
For permissions, please email: journals.permissions@oup.com
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Time to Save Time: Beneficial Effects of Blood Flow
Restriction Training and the Need to Quantify the Time
Potentially Saved by Its Application During
Musculoskeletal Rehabilitation
2
Introduction
muscle mass similar to that observed after HLRT in healthy
young18,19 and older19,20 individuals. BFR describes a technique in which the blood flow is manipulated by applying external mechanical pressure to the proximal portion
of the upper or lower extremities by using cuffs or elastic
bands. The pressure should be applied in such a way that
the arterial bloodflow is limited and the venous return is
occluded or highly restricted.21 Particularly, the prevented
venous return is thought to promote blood pooling and local
hypoxia, which aims to increase the level of metabolic stress22
(eg, inorganic phosphate), resulting in an accelerated fatigue
development23 and therefore lower cumulated mechanical
stress (due to significantly lower total work)24 compared to
LLRT without BFR. It is thought that the increased metabolic
stress together with mechanical tension induces a variety of
mechanisms (eg, increased recruitment of type II muscle fibers,
increased release of systemic and local hormones, increased
cell swelling), which are theorized to increase protein biosynthesis and provoke muscle hypertrophy.22,25 Hence, an optimal cuff pressure is of particular importance, because it is
intended to create an effective but also safe training stimulus.
In this respect, it is known that the cuff pressure required to
achieve an optimal training stimulus is related to various moderator variables,26 including individual characteristics27,28
(eg, blood pressure, limb circumference, body position), cuff
properties29,30 (eg, shape, width, material), and methodological factors21,31 (eg, exercise prescription, intermittent or continuous pressure). To account for these moderator variables,
it is recommended to set a personalized pressure based on
relative arterial occlusion pressure (AOP, lowest pressure at
which the arterial bloodflow is occluded),32 with pressures
ranging from 40% to 80% of AOP.21,33
Interestingly, the sole application of BFR to the extremities has been shown to attenuate muscle atrophy34,35 and,
in combination with aerobic exercise36,37 or LLRT,18–20 to
increase muscle mass and strength. Therefore, BFR training
provides a convenient solution, particular in the early stage
of musculoskeletal rehabilitation,5 to mitigate muscle atrophy
and strength loss without high or cumulated low mechanical
stress. In addition, BFR training in combination with aerobic
exercises or LLRT can be performed in subsequent stages
of musculoskeletal rehabilitation as an effective alternative
approach to HLRT to accelerate the hypertrophic adaptations, increase strength capacity, and regain activity levels.
The beneficial effects of integrating rehabilitative BFR
treatments following injury and/or surgery have been largely
presented.9,38 Although current studies have investigated
the beneficial effects of BFR training on muscular strength,
hypertrophy, and physical function compared with traditional
approaches at the same time point,39–41 little is known
about clinical outcomes with regard to the rehabilitation
progress (eg, earliest moment at which full weight bearing
is possible, time needed to reach the pre-injury and/or presurgery physical function level and/or return to physical
exercise and sport). In this regard, BFR training could be
used in different modalities (without exercise, in combination
with aerobic exercises or LLRT) and is therefore applicable
in almost all phases of musculoskeletal rehabilitation. We
assume that rehabilitation programs using various BFR
modalities allow patients to increase strength and activity
levels earlier than those undergoing traditional rehabilitation
programs. In the most favorable case, BFR might accelerate
the recovery process after injury and/or surgery and decrease
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Musculoskeletal injuries and/or surgical treatments are
usually associated with decreased neuromuscular capacity,
increased pain, and physical inactivity resulting in muscle
weakness1 and loss of muscle mass.2 These alterations are
associated with impaired physical function, reduced quality
of life, and/or high risk of re-injury. Furthermore, knee
injuries3 and quadriceps weakness4 are major risk factors
for the development of musculoskeletal diseases, especially
for osteoarthritis.5 The incidence of musculoskeletal diseases
has increased worldwide in the recent decades from 211.80
million to 334.74 million (1990 to 2017),6 and their impact
on patients’ quality of life7 as well as direct (eg, surgical procedure, hospital stay, rehabilitation) and indirect costs (eg, work
disability, reduced productivity) are considerable.8 Therefore,
targeting the loss of muscle mass and neuromuscular function
with tailored interventions during the rehabilitation process
is necessary to recover from injury and/or surgery and to
prevent the development of musculoskeletal diseases and their
associated health and economic burden.
The main goal of the musculoskeletal rehabilitation process is to regain the patients’ pre-injury and/or pre-surgery
physical function level.9 In this respect, the early stage of the
musculoskeletal rehabilitation process, which corresponds to
the healing and recovery phase,10 usually includes a period of
limb immobilization and/or bed rest11 to protect the injured
and/or reconstructed tissue and to prevent adverse events
(eg, [re-]injury). However, prolonged periods of limb immobilization and/or bed rest can result in several negative consequences for the patient. Whereas mechanical loading can
trigger hypertrophic responses of muscles,12 unloading situations or restricted weight bearing increases the progression of
muscular atrophy and weakness.13 Given the adverse effects
of such alterations mentioned above, implementing appropriate interventions aiming to prevent or attenuate the loss of
muscle mass and strength is a major issue in the early stages
of musculoskeletal rehabilitation in order to shorten the time
needed for recovery.10
Although other interventions are also suitable to preserve or
increase muscle mass and neuromuscular function, resistance
training is advised and favored to trigger neuromuscular
adaptations, which lead to an increased muscle strength.
It is widely recommended that moderate to high loads of
approximately 60% to 100% of the individual’s 1-repetitionmaximum (1-RM) are required to elicit gains in muscle mass
and strength (eg, 60%–70% 1-RM for novice to intermediate,
80%–100% 1-RM for advanced, and 60%–80% 1-RM for
older individuals).14 However, low-load resistance training
(LLRT; 30%–50% 1-RM) performed until exhaustion can
also increase muscle mass and strength.15,16
In patients undergoing the musculoskeletal rehabilitation
process, high-load resistance training (HLRT) as well as LLRT
performed until exhaustion can be contraindicated because
this is associated with considerable cumulated mechanical
stress on damaged or reconstructed tissues and could lead
to further injuries and/or pain.17 Thus, there is a need for
alternative rehabilitation interventions that are able to (1)
prevent atrophy and muscle weakness in the early stage of
recovery from injury and/or surgery, and (2) to increase muscle
mass and strength in the subsequent rehabilitation without the
application of high or cumulated low mechanical stress.
Blood flow restriction (BFR) training provides such an
alternative treatment option and has been shown to increase
Saving Time by Using BFR Training?
3
Bielitzki et al
the time needed to achieve the patients’ pre-injury and/or
pre-surgery physical function level. Therefore, the aim of this
perspective is to stimulate future research comparing the time
to achieve rehabilitative milestones and their physiological
bases in each stage of the musculoskeletal rehabilitation
process.
BFR Training Integrated in the Traditional
Rehabilitation Process May Shorten
Recovery Time
Loenneke et al2 proposed an evidence-based progressive
model consisting of 4 phases: (1) passive BFR (P-BFR); (2)
BFR in combination with aerobic training (BFR-AT); (3) BFR
in combination with LLRT (BFR-LLRT); and (4) BFR-LLRT
in combination with traditional HLRT. These phases can be
integrated into the stages of a traditional musculoskeletal
rehabilitation program (Figure).
Phase I: P-BFR
P-BFR training involves the application of cuffs to the extremities without physical activity. The primary effect of the intermittent application of P-BFR is to counter muscle atrophy and
strength loss, especially immediately after injury or surgery,
when the individual’s limbs are immobilized or the individual
is at bed rest.42 In previous studies, P-BFR was applied with
high43 up to fully occlusive pressures,35 but low pressures
have also been shown to induce beneficial effects.34 To date,
the standard protocol consists of 3 to 4 sets of 5 minutes with
a restriction pressure of 70% to 100% AOP and 3 minutes
of reperfusion.33 However, possible post-injury and/or postsurgery contraindications (eg, excess swelling, open fractures,
open soft tissue injuries, skin graft)44,45 must be considered
before this training modality can be used. P-BFR training
may positively influence mitochondrial and vascular function, resulting in an improved local aerobic capacity, because
this was shown following an intermittent occlusion protocol
(≥100% AOP) applied in healthy people.46 Besides these
effects, studies have shown that the repetitive restriction of
blood flow in inactive participants can reduce pain perception
following surgery47 as well as after muscle damaging exercise,48 which might be due to conditioned pain modulation,
related to hypoxia or inflammation.49 These effects of P-BFR
might reduce the impairments associated with surgery, injury,
limb immobilization, and/or bed rest, resulting in an improved
level of physical functioning compared with the traditional
rehabilitation approach. Consequently, P-BFR might reduce
the time to enter subsequent rehabilitation phases.
Phase II: BFR-AT
BFR-AT can be used in the inpatient as well as outpatient
rehabilitation as a supplement to active mobilization.
The primary goals of BFR-AT are to further attenuate
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Figure. Theoretical model comparing the time courses of the musculoskeletal rehabilitation process for the lower limbs with and without blood flow
restriction (BFR) training until the pre-injury or pre-surgery physical function level is reached. The progression from limb immobilization and/or bed rest
with passive BFR (P-BFR), followed by BFR in combination with aerobic exercises (BFR-AT), followed by blood flow restriction with low-load resistance
training (BFR-LLRT), and followed by BFR-LLRT combined with high-load resistance training (BFR-LLRT + HLRT) is depicted on the left side. The
directions of training-induced changes for each phase are depicted with arrows (↑ increase, ↔ unchanged, ↓ decrease). On the right side, the same
training-induced changes and phases are described for the traditional progression following musculoskeletal injury or surgery. Although the illustration
refers to the lower extremities, the model could also be applied to the upper extremities. However, there is little evidence supporting the effectiveness
of BFR in the musculoskeletal rehabilitation for the upper limb.
4
Phase III: BFR-LLRT
Several reviews5,17,33 have shown that BFR-LLRT increases
muscle mass and strength in the rehabilitation of musculoskeletal injuries and after surgery. The primary aim of BFRLLRT is to enhance muscle mass and strength in order to
tolerate higher loads and regain the pre-injury or pre-surgery
physical function level.56 Due to lower mechanical stress,
BFR-LLRT can be performed in an earlier phase of the rehabilitation process compared with HLRT and LLRT performed
until exhaustion. As already stated, BFR-LLRT can induce
similar increases in muscle mass compared with HLRT19 and
LLRT performed until exhaustion.24 Furthermore, despite
mixed results of studies investigating muscle activation indices
after BFR-LLRT, it might be that this training modality also
induces neural adaptations, which contribute to the increases
in strength.57 For example, it has been demonstrated that
surface electromyography amplitudes recorded during maximal voluntary contractions were increased after BFR-LLRT
compared to LLRT without BFR.58 However, these results
must be interpreted with caution because surface electromyography amplitudes have been questioned as a valid indicator
for the neural drive to the muscles,59 and they are sensitive
to changes in electrode placement and body composition,
which are very likely to occur during training studies. The
influence of the latter confounders can only be minimized by
adequate normalization.60 Some studies have used peripheral
nerve stimulation to quantify neural adaptations in response
to BFR-LLRT and have not found a significant change in
muscle activation indices in healthy people.61,62 However,
these studies have only investigated a small number of individuals with a high baseline muscle activation, which limits
the range for improvements and might mask the neural adaptations after BFR-LLRT. Therefore, it would be of interest
to analyze the effect of BFR-LLRT on neural adaptations in
patients suffering from arthrogenic muscle inhibition, which
is defined as the long-lasting inability to fully activate a
muscle or muscle group and which contributes to the impaired
strength capacity, for example, after surgery and/or traumatic injury of the knee joint.63 Besides these aspects, it
was recently shown that BFR-LLRT increases the capillaryto-muscle-area ratio64 with potential positive consequences
for the hypertrophic response to a subsequent HLRT as well
as for endurance performance. In addition, BFR-LLRT might
induce acute and chronic hypoalgesia effects by triggering
specific pain-modulating mechanisms mentioned above.49 For
example, Hughes and Patterson65 have found that BFR-LLRT
with a high pressure increased the pressure pain threshold
in the exercising limb more than HLRT. They concluded
that the increased beta-endorphin production and conditioned
pain modulation due to BFR-induced muscle discomfort contributed to the heightened pressure pain threshold following
BFR-LLRT. In summary, the effects of BFR-LLRT on muscle
growth and strength as well as on potential neural adaptions
and pain perception might reduce the time needed for rehabilitation and could create an optimal precondition for the
neuromuscular adaptations of a subsequent HLRT.
Phase IV: BFR-LLRT Combined With HLRT
The prerequisite for starting HLRT during outpatient rehabilitation is the ability to perform exercises with 65% to 70%
of the preoperative 1-RM without adverse effects.56 High
loads lead to high muscle tension and to the initialization of
additional adaptations, which cannot be generated by BFRLLRT alone. Hence, to achieve optimal training effects such
as tendon stiffness and neuromuscular adaptations, high loads
are likely required in addition to low load-induced metabolic
stress.66 However, recent investigations indicated that BFRLLRT is able to induce similar morphological and mechanical
adaptations of the Achilles tendon as HLRT.67 Nevertheless,
the current state of research is limited regarding this topic.
In general, the patient must be physically able to safely bear
heavy loads before starting HLRT. We hypothesize that an
application of BFR in the previous phases leads to an earlier
achievement of the HLRT phase.
Investigating the Time Saved by BFR Training
During Musculoskeletal Rehabilitation Is
Urgent
Based on the information presented above, we assume that
studies investigating the effect of BFR training during musculoskeletal rehabilitation should not only analyze the adaptations (eg, muscular, neural, vascular, perceptual) and changes
in performance (eg, strength and endurance) after longer periods of training at 1 specific point in time but also during a BFR
training program with a higher measurement frequency (eg,
≤1 week). This approach would allow to examine at which
point in time both BFR and the traditional rehabilitation
induce similar adaptations and alterations in performance.
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atrophy and strength loss, improve muscle activation and
control, and normalize movement kinematics (eg, knee
joint kinematic), which are necessary for applying LLRT.5
BFR-AT is usually performed in combination with walking
or cycling exercises and has been shown to enhance
muscle mass and strength as well as cardiorespiratory
capacity (eg, maximal oxygen uptake).33 Improvements in
maximal oxygen uptake might be attributed to increases
in muscle mass and capillary density.50 It is assumed
that BFR-AT promotes angiogenesis, capillary density, and
mitochondrial biogenesis via cell signaling (eg, via peroxisome proliferator-activated receptor gamma coactivator
1-alpha and vascular endothelial growth factor)51 induced by
intermittent localized hypoxia (eg, via hypoxia-induced factor
1-alpha).52 The extent of capillarization at baseline may play
an important role for muscle hypertrophy following resistance
training in older males and females.53 Therefore, it can
be speculated that BFR-AT creates a beneficial prerequisite
for the hypertrophic response to a subsequent resistance
training, at least in the elderly. The increased capillary density
might also promote physical fatigue resistance,54 which is of
importance during the rehabilitation process and for activities
of daily living. Moreover, it is conceivable that BFR-AT evokes
hypoalgesia effects (eg, due to activation of endogenous opioid
and endocannabinoid systems, conditioned pain modulation,
recruitment of higher threshold motor units, and altered
interaction of cardiovascular and pain regulatory systems)49
because it mimics endurance exercise at higher intensities,
which appears to elicit exercise-induced hypoalgesia as well.55
Therefore, we speculate that BFR-AT not only allows an
individual to enter the next rehabilitation phase earlier, but
also creates a more favorable precondition for resistance
training–induced hypertrophy, as well as physical fatigue
resistance, compared with traditional low-intensity aerobic
exercise without BFR.
Saving Time by Using BFR Training?
5
Bielitzki et al
Basic Research: Quantifying the Time Saved by BFR
Training to Induce Similar Physiological
Adaptations Compared With the Traditional
Approach
As described above, BFR training is associated with superior
physiological adaptations (eg, muscle mass and strength,68
hypoalgesia69 ) compared with the rehabilitation phase–
specific traditional approach without BFR. Because the
determination of the time saved by BFR training during musculoskeletal rehabilitation requires a high measurement frequency (eg, ≤1 week), assessments should have minimal influence on the healing process and should be carefully selected
as well as adapted to the respective patient population.
For example, to monitor changes in skeletal muscles,
diagnostic imaging, including magnetic resonance imaging,70
ultrasound,71 computed tomography,72 and dual energy
X-ray absorptiometry,73 can be used. If possible for the
patient, these measures should be complemented with strength
and endurance measurements to elucidate the associations
between alterations in morphological parameters and changes
in performance. The performance assessments should be
substituted by reliable neurophysiological techniques, such
as peripheral nerve stimulation and/or transcranial magnetic
stimulation, to detect adaptions within the nervous system
that contribute to changes in performance.74 Monitoring of
muscle oxygenation at rest or during submaximal exercise
with near-infrared spectroscopy75 could provide additional
insights into the adaptions during a BFR training program
(eg, changes in vascular function and/or muscle metabolism).
Exercise-induced hypoalgesia can be investigated using pain
threshold or pain tolerance assessments after the application
of different stimuli (eg, thermal, electrical, mechanical,
ischemic stimuli),55 and molecular changes (eg, insulin-like
growth factor 1, growth hormone, human growth factor,
reactive oxygen species, inflammatory markers)22,38 can be
analyzed via blood samples.
Although morphological and blood analyses can be performed without repercussion on the patient, a high frequency
of performance measurements introduces the problem that
the measurements per se might induce different adaptations,
which bias the outcome. Therefore, randomized controlled
trials with an adequate sample size should be conducted
in which the experimental groups as well as the control
groups must perform the same number of assessments. This
approach would allow to minimize the measurement-induced
bias.76
Applied Research: Quantifying the Time Saved by
BFR Training to Induce Similar Physical Functioning
and Quality of Life Compared With the Traditional
Approach
Besides the investigation of BFR-induced physiological adaptations, simple clinical tests should be adopted within short
time intervals to quantify changes in performance as well
as the time saved by BFR-assisted rehabilitation. Depending on the physical condition of patients, these tests should
also be applied with a high measurement frequency (eg, ≤1
week). There are a lot of reliable objective clinical assessments
that can be used to monitor muscle strength and power
(eg, 5-repetition or 30-second sit-to-stand test, stair-climbing
test),77,78 mobility and function of the lower extremities (eg,
Timed “Up & Go” Test),79 functional exercise and endurance
capacity (eg, 6-Minute Walk Test)80 or other submaximal
clinical exercise tests), and flexibility (eg, range of motion
assessment).81 The combination of these measures with subjective psychometric assessments, such as pathology-related
scores (eg, Hospital for Special Surgery Knee Score, Western
Ontario and McMaster Universities Osteoarthritis Index)82,83
and quality of life (eg, 5-level European Quality of Life fivedimensional Questionaire [EQ-5D-5L], 36-Item Short Form
Health Survey [SF-36]),84,85 does not only allow to quantify
the time saved by BFR-assisted rehabilitation regarding physical functioning but also if and to which extent this translates
in accelerated subjective psychophysiological improvements.
As mentioned above, these studies should be conducted as
randomized controlled trials with an adequate sample size
to reduce the adaptation bias generated by repetitive performance testing.
Safety Considerations
Besides the above outlined benefits of BFR training, it is
necessary to consider its safety and essential preconditions
when used during musculoskeletal rehabilitation. This is of
particular importance for patients with comorbidities such as
cardiovascular, metabolic, and/or pulmonary diseases. Several
papers have reviewed and discussed the safety of BFR training
in different populations.44,86 These articles have frequently
focused on cardiovascular responses to BFR and the risk
of thromboembolism. In this respect, studies have generally
found that BFR-LLRT with continuous pressure (ie, no deflation of the cuffs between sets) elicits slightly higher acute
increases in heart rate, systolic blood pressure, diastolic blood
pressure, mean blood pressure, and cardiac output compared
with the same exercise without BFR (ie, matched for load
and volume).33,44,87 However, when resistance exercises are
performed with low loads until exhaustion or with high loads,
these hemodynamic changes are similar or lower during BFRLLRT.33,44,87 Most studies investigating the effect of BFR
on thromboembolism have measured direct blood markers
of coagulation, for example, fibrinogen and D-dimer.44 In
these articles, blood markers of coagulation were not elevated
following BFR training in healthy young88,89 and older90
individuals as well as in patients with ischemic heart disease.91
The most frequently reported side effects associated with BFR
are subcutaneous hemorrhage (13.1%) and numbness (1.3%),
whereas thromboembolism was rare (0.055%).92 Although
the risk of thromboembolism during BFR training is likely
similar to that during traditional resistance training in healthy
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The information thus collected will help to quantify the time
saved by BFR training during musculoskeletal rehabilitation.
This aspect is of particular importance for patients, because
the potentially accelerated recovery of physical functioning
would allow to participate earlier in their social and/or working life with consequences for their quality of life. Furthermore, other stakeholders in the health care system, such as
physicians, nurses, physical therapists, and insurance companies, might benefit from BFR rehabilitation in terms of work
and financial burden.
To understand the mechanisms and performance benefits
by which BFR training reduces the time for each rehabilitation
phase, a combination of basic research and applied research
is required.
6
Saving Time by Using BFR Training?
Limitations
With regard to the presented progressive model of a BFRassisted rehabilitation, there are some limitations. Although
there are some studies regarding BFR training–induced effects
on body parts that are proximal to the cuff (eg, hip,96 shoulder,97 chest),98,99 this topic has hardly been investigated.
Therefore, the postulated beneficial effects of BFR training
might be currently limited to the muscles distal to the cuff. In
addition, it is still not clear if the regeneration of other tissues
like bones, tendons, ligaments, and fascia can be accelerated
by a BFR-assisted rehabilitation and represents a limiting factor. Furthermore, BFR is associated with amplified exerciseinduced effort and pain perception,23 which might minimize participants’ adherence to the BFR training program.100
Research in rehabilitation patients, however, indicates that
higher ratings of exercise-induced muscle pain experienced
with BFR did not limit adherence to the training.101
Author Contributions
Concept/idea/research design: R. Bielitzki, T. Behrendt, M. Behrens,
L. Schega
Writing: R. Bielitzki, T. Behrendt, M. Behrens, L. Schega
Consultation (including review of manuscript before submitting):
R. Bielitzki, T. Behrendt, M. Behrens, L. Schega
Funding
The author(s) received no financial support for the research, authorship,
and/or publication of this article.
Disclosures
The authors completed the ICMJE Form for Disclosure of Potential
Conflicts of Interest and reported no conflicts of interest.
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adults, the pathogenesis of the formation of thromboembolism is multifactorial, and post-injury and/or post-surgery
patients need further precautions.93
Therefore, to reduce the risk of adverse events during
or after BFR training, the following 3 aspects should be
considered: (1) screening, (2) monitoring, and (3) application.
The patients should (1) be screened for potential risk factors
and/or contraindications. These include intrinsic and extrinsic
factors, which are summarized elsewhere, to develop an applicable screening tool.44,94,95 Furthermore, (2) hemodynamic
and physiological responses (eg, blood pressure, heart rate),
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and pain sensations related to the injured/operated tissue (eg,
visual analogue scale) should be monitored during exercise
and throughout the whole rehabilitation process.56 As mentioned above, (3) the correct application of BFR training is of
particular importance to create a safe stimulus. Although, to
the best of our knowledge, there are no standardized recommendations for the use of BFR training in clinical populations,
evidence-based guidelines for the application of P-BFR, BFRAT, and BFR-LLRT are presented in a recently published
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