ENERGY
SYSTEMS
E N E RG Y SYS T E M S
ENERGY SYSTEMS
How Do We Power Exercise?
•
In order to produce movement/exercise, we need to breakdown a
molecule known as ATP (adenosine triphosphate) which you can
essentially look at as gasoline for our body
•
As we breakdown carbohydrates, fats, and protein we can generate ATP
primarily through three different main metabolic pathways which can
then be targeted through training
•
The interesting point is we do not store a lot of ATP in our muscles and
therefore must generate it immediately as we begin to exercise
•
Technically, the amount of ATP that is stored within muscle will only be
enough to power exercise for a few seconds
•
With all that being said, just think of ATP as gasoline which we can acquire
three main ways which will provide the energy to exercise
•
•
The Phosphagen System (ATP-PC)
•
The Glycolytic System
•
The Aerobic System (Oxidative Phosphorylation)
A common analogy I like to use in class to describe how our body needs
ATP to fuel exercise and not specifically the carbohydrates, fats, and
protein is going to a laundromat
•
•
Typically, when you go to a laundromat you will put dollar bills into
a machine that will then give you quarters. The quarters are what
actually powers that machine and not the actual dollar bills you
started with. Think of the dollar bills as carbohydrates, fats and
protein and the quarters as ATP molecules
The first two systems can generate ATP without oxygen being required
in the metabolic pathway so we term the Phosphagen and Glycolytic
systems “anaerobic metabolism”
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E N E RG Y SYS T E M S
•
On the other hand, the Aerobic/Oxidative Phosphorylation system is
termed “aerobic metabolism”
•
The most important point to understand when discussing energy systems
is all three primary pathways are always being used and contributing to
total ATP production, however, which energy system is dominant during a
particular exercise task is directly related to the intensity and duration of
the exercise
Basic Energy System Table
EXERCISE DURATION
INTENSITY
MAIN ENERGY SYSTEM
0-6 seconds
Maximal
Phosphagen
6-30 seconds
Near-maximal
Phosphagen + Glycolysis
30-120 seconds
High
Glycolysis
2-3 minutes
Moderate
Aerobic/Glycolysis
>3 minutes
Low
Aerobic
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E N E RG Y SYS T E M S
Energy System Training
EMPHASIS
EFFORT
DURATION
PROGRAMMING
EXAMPLE
Max Speed/Power
100%
0-10 seconds
10 second sprint
on an airbike with
a 90 second rest
Sustained high
intensity effort
100%
10 seconds - 2
minutes
30 second sprint
on an airbike with
a 30 second rest
2 minutes or more
3 minute interval
on an airbike with
a 3 minute rest
Aerobic/Endurance
100%
The Phosphagen (ATP-PC) System
•
The Phosphagen System is the simplest of all the energy pathways to
understand
•
Essentially we are using another energy molecule known as creatine
phosphate to help generate ATP extremely fast
•
Most people recognize the word creatine because it is one of the most
common supplements in the lifting community
•
Creatine helps your muscles increase strength and power capabilities and
is one of the most scientifically backed supplements you can take
•
The Phosphagen System is the fastest off all three systems with regard to
ATP production but will fatigue the quickest
•
Think of something like a high performance sports car that has a
tremendous amount of speed and power but won’t go far and has terrible
gas milage (a drag race is a good example)
•
What creatine does is act like an Uber driver that will deliver an essential
building block for our muscle cells to generate ATP
•
This energy system will typically only provide enough energy to power all
out exercise for about 2-12 seconds
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E N E RG Y SYS T E M S
The Glycolytic System
•
In this system we are using carbohydrates (specifically glucose) to break
down so we can form ATP
•
Glucose comes from dietary carbohydrates as well as when we breakdown
glycogen (which is nothing more than stored glucose)
•
We store glycogen in two key areas within our body
•
Liver – about 20% of stored glycogen is in the liver
•
Skeletal muscle – about 80% of stored glycogen is in skeletal muscle
•
The actual breakdown of glucose is about a 10-12 step process that will
lead to a net of 2 ATPs if you start with glucose and actually a net of 3
ATPS is you start with glycogen
•
This is more than we would get from the Phosphagen System but it does
not occur as fast and is a little more resistant to fatigue
•
Also, the glycolytic system can sustain an all-out effort for a longer time
f rame which is typically somewhere between 15 seconds all the way to a
few minutes
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E N E RG Y SYS T E M S
•
This is where you want to think of something like heavy duty truck that
will produce a lot of power and speed for a longer time period but not as
fast as a drag racer
•
When intensity is high enough and we need ATP at a fast enough rate we
will generate lactate as sort of a final product of stressing the glycolytic
system
•
Lactate is that molecule that has been demonized for creating soreness
and fatigue in muscle. Many people think lactate is also the reason for
the “muscle burn” many lifters experience. The truth is lactate is simply
correlated with fatigue and soreness but is absolutely not the direct cause.
•
The process of generating lactate helps to keep glycolysis going while at
the same time we can actually break lactate down in other areas than it
was created to help generate more ATP and continue exercise
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E N E RG Y SYS T E M S
The Aerobic System (Oxidative Phosphorylation)
•
The Aerobic System is by far the most complex of the three primary
energy system pathways
•
When we use the aerobic system we are using oxygen as a part of the
process to directly help with the production of ATP (we call this cellular
respiration)
•
The main site of the aerobic system is in the mitochondria of the cell (we
all remember hearing about the mitochondria in like the fifth grade when
teachers would say “the mitochondria is the powerhouse of the cell”.)
•
Basically, as we break down carbohydrates, fats, and protein for the
purpose of creating ATP to power exercise, we bring part of that nutrient
to the mitochondria which goes through even more breakdown before we
eventually make all the ATP we can
•
The two main sources of fuel during exercise are carbohydrates and fats
and which one we are using more of at any one moment is typically
dictated by things like intensity, duration, diet, genetics, and training
status
•
Carbohydrates will provide about 32-38 ATPs whereas fats typically provide
about 100+ ATPs depending on the specific fat broken down (fat provides
more ATPs but takes longer to break down)
•
The type of fuel we rely on the most mainly depends on the intensity and
duration of the exercise
•
When we are exercising at lower intensities and for a longer duration we
tend to use more fat for fuel
•
When we are exercising at higher intensities (short bouts and longer
bouts) we tend to rely more on carbohydrates for fuel
•
It is important to note that during exercise/sport in more of an interval
fashion where there are periods of high intensity followed by periods of
lower intensity, the aerobic system is more important than people think
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E N E RG Y SYS T E M S
•
The aerobic system may only contribute about 10% to total energy
production during a single sprint however, during repeated effort sprints
where someone is completing many sprints in the same session, the
contribution of the aerobic system could be as much as 50%
•
Lastly, protein is not typically a large energy source for us during a workout
•
During very long duration exercise such as marathon, triathlon,
ultramarathon etc. we begin to rely more on protein for fuel but it is
worth noting protein is a very inefficient fuel source
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E N E RG Y SYS T E M S
Energy System Examples
ENERGY SYSTEM
TYPES OF ACTIVITY
ATP PRODUCTION
Phosphagen
40 yard dash/
Olympic weightlifting
1
Glycolytic
200 meter sprint/
45 second bike sprint
2-3
Aerobic
1000 meter row/marathon
From carbs = 32-38/
From fats = about 100+
Energy System Fuel and Energy Production Simplified
ENERGY SYSTEM
Phosphagen
Glycolytic
Aerobic
SPEED OF ENERGY
PRODUCTION
Very High
High
Low
ABILITY TO
SUSTAIN ENERGY
PRODUCTION
FUELS USED
Very Low
ATP and Creatine
Phosphate in
skeletal muscle
Low
Blood sugar,
and muscle/liver
glycogen (stored
carbs)
Very High
Blood sugar,
and muscle/liver
glycogen (stored
carbs) and fat
(stored underneath
the skin, around
vital organs, and
within muscle)
Energy System Work:Rest Ratio Examples
% OF MAXIMAL
POWER OUTPUT
MAIN ENERGY
SYSTEM USED
DURATION
RANGE OF
WORK:REST
RATIOS
90-100% Effort
Phosphagen
1-10 Seconds
1:10 to 1:20
70-90% Effort
Glycolytic
10-30 Seconds
1:3 to 1:5
30-70% Effort
Glycolytic/Aerobic
1-3 Minutes
1.2 to 1.4
10-35% Effort
Aerobic
>3 Minutes
1:1 to 1:3
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E N E RG Y SYS T E M S
Where Do We Store Fuel For Exercise and About How Much Is Stored?
LOCATION
ESTIMATED AMOUNT OF STORED
CALORIES IN THE FORM OF THAT FUEL
Carbohydrates Stored In The Liver
500 Calories
Carbohydrates Stored
In The Skeletal Muscle
2000 Calories
Carbohydrates In The Blood
60 Calories
Fat Stored Under The Skin And
Around Vital Organs
75,000 Calories
Fat Stored Within Skeletal Muscle
1500 Calories
The Aerobic/Anaerobic Continuum
MOST AEROBIC
Marathon
5K Run
Soccer
400 Meter Swim
800 Meter Sprint
40 Yard Dash
Olympic Weightlifting
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E N E RG Y SYS T E M S
MOST ANAEROBIC
Phosphagen (ATP-PC) System Basic Programming Guidelines
PHOSPHAGEN (ATP-PC) POWER
Duration
Up to 10 Seconds
Work:Rest Ratio
1:10 or greater
Intensity
Maximal Effort
Reps
5-8
Sets
1-5
Phosphagen (ATP-PC) System Basic Programming Guidelines
PHOSPHAGEN (ATP-PC) CAPACITY
Duration
Up to 15 Seconds
Work:Rest Ratio
1:3 to 1:4
Intensity
Maximal Effort
Reps
5-8
Sets
1-3
Glycolytic System Basic Programming Guidelines
GLYCOLYTIC POWER
Duration
30-50 Seconds
Work:Rest Ratio
1:4 to 1:5
Intensity
Submaximal Effort
Reps
4-6
Sets
1-4
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E N E RG Y SYS T E M S
Glycolytic System Basic Programming Guidelines
GLYCOLYTIC CAPACITY
Duration
60-90 Seconds
Work:Rest Ratio
1:3 to 1:4
Intensity
High Effort
Reps
8-12
Sets
1-3
Aerobic System Basic Programming Guidelines
AEROBIC POWER
Duration
1-2 Minutes
Work:Rest Ratio
1:1 to 1:5
Intensity
Intermediate Effort
Reps
5-8
Sets
1-3
Aerobic System Basic Programming Guidelines
AEROBIC CAPACITY
Duration
1-10 Minutes
Work:Rest Ratio
1:1 to 1:3
Intensity
Intermediate Effort
Reps
5-15
Sets
1-3
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