1. Energy for Muscular Activity
Unit 1: Human Anatomy
Energy
Systems
Energy for Muscular Activity
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2. How a Muscle Uses Energy
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How a Muscle Uses Energy
Energy Systems
The ability to move, work or play sports is dependant on supplying sufficient energy for the duration of the activity.
To achieve muscle contraction, chemical energy has to be converted into mechanical energy. The source of this energy is stored in the high energy phosphate bonds of ATP.
An ATP molecule consists of an adenosine molecule bonded to three phosphate groups.
Adenosine P

3. How a Muscle Uses Energy
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How a Muscle Uses Energy
Energy Systems
To release energy, a phosphate molecule breaks away from the phosphate group to form adenosine diphosphate (ADP).
Energy
Heat P
Adenosine
Adenosine P
Hydrolysis
Breaking ATP into ADP releases energy and allows cross bridge formation to occur inside the muscle.

4. How a Muscle Uses Energy
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How a Muscle Uses Energy
Energy Systems
A cell stores only a small amount of ATP. It can provide energy for only 5 seconds of strenuous exercise. ATP has to be continuously replenished since it is the only direct energy source for muscle contraction. When ADP accumulates the body begins the process of restoring ATP. + P
To accomplish this synthesis, energy must be available;
Energy is supplied through the breakdown of complex molecules, such as fats and carbohydrates.
Energy
Adenosine
Adenosine P

5. How a Muscle Uses Energy
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How a Muscle Uses Energy
Energy Systems
The production of ATP involves different energy systems designated as anaerobic or aerobic each producing ATP at a distinct rate and duration.
Anaerobic – without oxygen
Aerobic – with oxygen
The biochemical reactions in each system are complex, and the body’s preference for anaerobic or aerobic metabolism depends on several factors including the :
type of muscle fibre involved in the activity;
intensity and duration of exercise;
level of training.

6. Woodland Christian High School
Restoration of ATP
Energy Systems

7. The Three Energy Systems
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The Three Energy Systems
Energy Systems
Anaerobic
Energy systems that do not rely on the immediate use of oxygen.
There are two types of anaerobic energy systems.
Anaerobic Alactic
A short term energy of both fast and slow twitch muscle fibres that does not require oxygen and does not produce lactic acid.
Anaerobic Lactic
A fast twitch muscle energy system which does not require the immediate use of oxygen but does produce lactic acid
Aerobic
A slow twitch muscle energy system which is used in prolonged continuous activity in the presence of oxygen and does not produce lactic acid.

8. Anaerobic Alactic: ATP-CP System
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Anaerobic Alactic: ATP-CP System
Energy Systems
An immediate - high energy phosphate system
Involves activities such as weight lifting, high jump, long jump, shot put, discus 50 metre sprint, 25 metre swim
Involves high power output activities that require an immediate high rate of energy production for a short period of time
Energy
Heat
Adenosine P

9. Anaerobic Alactic: ATP-CP System
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Anaerobic Alactic: ATP-CP System
Energy Systems
As muscle contraction begins, the body may not be able to supply ATP to the contracting muscle cells as rapidly as required. Creatine phosphate serves as a quick available energy reserve for muscles as it is broken down into creatine and phosphate.
Creatine P
CP CP +
ATP
The free phosphate ions bonds with ADP to produce ATP and leave behind creatine. The new ATP molecule is stored as potential energy. Creatine phosphate can only support muscle contraction for another 3 to 4 seconds.
Energy
Adenosine P P

10. Anaerobic Alactic Characteristics
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Anaerobic Alactic Characteristics
Energy Systems
Only a small amount of ATP and CP is stored in muscle fibres;
Uses very large amounts of energy in a short period of time;
The rate of recovery is rapid. After a brief rest, the system is recharged and ready for the next sprint;
Oxygen is not required;
Lactic acid is not produced;
Provides energy for muscles for the first 5-10 seconds of high intense activity;
Uses both fast and slow twitch muscles;
Work output is relatively high.

11. Characteristics of the Anaerobic Alactic System
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Characteristics of the Anaerobic Alactic System
Energy Systems
Energy System
Anaerobic Alactic
Type of Activity
short sprints used in baseball,
pole vault, long jump, triple jump
Range of Maximum Work Times
0 – 10 seconds
Oxygen Required
None
Lactic Acid Produced
Energy Source
Chemical energy stored in muscles
Adenosine Triphosphate
Creatine and Phosphate
End Products of Fuel Breakdown
Adenosine Diphosphate
Creatine Phosphate plus energy
Muscle Fibre Recruited
Fast and Slow Twitch
Work Output per Unit of Time
High

12. Anaerobic Lactic: The Lactic Acid System
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Anaerobic Lactic: The Lactic Acid System
Energy Systems
If an athlete continues to work beyond 10 s, a second energy system uses glucose to provide energy. Glucose, which is stored in muscle cells and in the liver (glycogen), can provide immediate energy without oxygen.
Glucose
Lactic
Acid
When glucose is converted into energy lactic acid is produced.
Energy
ADP + P ATP

13. The Effects of Lactic Acid
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The Effects of Lactic Acid
Energy Systems
During intense exercise, lactic acid builds up in the blood faster than it can be removed. As lactic acid build up an athlete will reach their anaerobic threshold.
High
Fast-twitch Type B fibres dominate
The anaerobic threshold is the highest intensity of workload at which lactate clearance still keeps pace with lactate production.
Moderate
Fast-twitch type A fibres are recruited
Once this level is reached the intensity level must decrease to reduce the amount of lactic acid build-up
E X E R C I S E I N T E N S I T Y
Low
Slow twitch fibres dominate

14. At the anaerobic threshold the muscle loses its ability
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Anaerobic Threshold
Energy Systems
Anaerobic threshold is the point where a person begins to feel discomfort and a burning sensation in their muscles.
At the anaerobic threshold the muscle loses its ability
to contract resulting in muscle fatigue.

15. The Effects of Lactic Acid
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The Effects of Lactic Acid
Energy Systems
Lactic acid causes pH changes in the muscle fibres and they can no longer respond to stimulation.
Lactic acid interferes with cross-bridge bonding by limiting the strength of the fibre contraction.
A high production of lactic acid ultimately limits continued performance in intense activities

16. The Effects of Lactic Acid
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The Effects of Lactic Acid
Energy Systems
When lactic acid accumulates, extreme fatigue sets in and oxygen deficit develops.
Oxygen deficit is the reason you must
breathe rapidly and deeply for a few
minutes after strenuous exercise.
After you stop anaerobic exercise, your body needs extra oxygen to burn up the excess lactic acid and return your energy reserves to normal.
Lactic acid cannot be removed until extra oxygen is supplied to convert it to harmless, re-usable products.

17. Characteristics of the Lactic Acid System
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Characteristics of the Lactic Acid System
Energy Systems
The energy source comes entirely from glucose;
Oxygen is not required;
Energy is provided for or 120 seconds depending on conditioning;
Uses predominately fast twitch muscle fibres;
Work output is moderate;
Used in sports such as football, basketball and hockey.

18. Characteristics of the Lactic Acid System
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Characteristics of the Lactic Acid System
Energy Systems
Energy System
Anaerobic Lactic
Type of Activity
games such as football,
basketball, hockey
Range of Maximum Work Times
10 seconds to 60 or 120 seconds depending on conditioning
Oxygen Required
None or very little
Lactic Acid Produced
Yes, accumulated faster
than it can be removed
Energy Source
Entirely carbohydrate
End Products of Fuel Breakdown
Lactic Acid
Muscle Fibre Recruited
Predominately Fast Twitch
Work Output per Unit of Time
Medium

19. Effects of Training on the Lactic Acid System
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Effects of Training on the Lactic Acid System
Energy Systems
At any level of work, the rate of lactic acid build-up is decreased through training. Improvements in the cardiovascular system deliver an increased blood flow to the working muscle and,
The individual can work out at a higher rate of activity before lactic acid build-up begins.
The individual is able to “handle” a higher level of lactic acid.
Trained individuals are able to remove lactic acid faster from exercising muscles.
The anaerobic threshold rises.

20. The Aerobic System: Long Term Energy
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The Aerobic System: Long Term Energy
Energy Systems
As the length of an exercise session continues the athlete requires a steady power output over a long period of time
Exercise performed at a lower intensity level relies almost exclusively on the aerobic system for energy production and required the athlete to use oxygen as its source of energy.
Most daily activities use energy provided by the aerobic energy system
The oxygen energy system is the most important energy system in the body.
While this pathway cannot generate the speed of the anaerobic, it does provide a great deal more efficiency and endurance.

21. The Aerobic System: Long Term Energy
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The Aerobic System: Long Term Energy
Energy Systems
The aerobic system energy requires the metabolism of
Fats
Proteins
Oxygen
Glucose stored in muscles
combine to produce
ADP + P  ATP
Energy
CO2
Water
using energy produces

22. Characteristics of the Aerobic System
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Characteristics of the Aerobic System
Energy Systems
The oxygen system is highly efficient. When oxygen is used in muscle cells:
it prevents the build-up of lactic acid;
an individual can work out longer before lactic acid build-up begins;
it is able to remove lactic acid from muscles allowing the muscle to continue to contract allowing exercise to continue;
it promotes the re-synthesis of ATP for energy when work output is low.

23. Characteristics of the Aerobic System
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Characteristics of the Aerobic System
Energy Systems
As the duration of activity increases, the contribution of the aerobic system to the total energy requirement increases.
Due to this, there are two limitations to the aerobic system:
The system requires a continuous supply
of oxygen and fuel sources necessary
for the aerobic metabolism.
The use of ATP must be relatively slow
to allow the process to meet the energy
demands.

24. Characteristics of the Aerobic System
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Characteristics of the Aerobic System
Energy Systems
Energy System
Aerobic
Type of Activity
long distance running, cross
country skiing, swimming
Range of Maximum Work Times
120 seconds plus
Oxygen Required
Yes
Lactic Acid Produced
Depends on intensity
Energy Source
Mixture of fat and carbohydrate
End Products of Fuel Breakdown
CO2 and H2O
Muscle Fibre Recruited
Slow twitch and
some fast twitch
Work Output per Unit of Time
Low

25. Woodland Christian High School
Aerobic Power
Energy Systems
Oxygen uptake
The power of the aerobic system is generally evaluated by measuring the maximum volume of oxygen that can be consumed in a given amount of time. This can be measured by determining the amount of oxygen exhaled as compared to the amount inhaled.
As the intensity of work increases the capacity of aerobic system reaches a maximum. The greatest rate at which oxygen can be taken in and used during exercise is referred to maximal oxygen consumption or (VO2max)

26. Woodland Christian High School
Aerobic Power – Max VO2
Energy Systems
Each person has his or her own maximal rate of oxygen consumption (VO2 max)
The maximal rate at which oxygen can be used is genetically determined.
The VO2 max values of trained athletes will reach for males and for females
A normal VO2 max for most high school athletes
would fall somewhere between 30 and 50 range.
The more active we are the higher the VO2 max will be in that range.

27. Max VO2 Standards for 2.4 km Run
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Max VO2 Standards for 2.4 km Run
Energy Systems
Time
Max VO2
8:00
65.2
10:45
48.9
8:15
64.9
11.00
47.6
8:30
63.2
11.15
46.1
8:45
61.3
11:30
44.7
9:00
59.1
11.45
43.2
9:15
57.9
12:00
41.7
9:30
56.7
12:15
40.3
9:45
55.6
12:30
38.9
10:00
53.1
12:45
37.4
10:15
51.8
13:00
36.2
10:30
50.1
13:15
35.1

28. Max VO2 Standards for Beep Test
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Max VO2 Standards for Beep Test
Energy Systems

29. Max VO2 Norms Energy Systems Woodland Christian High School
Female (values in ml/kg/min)
Age
Very Poor
Poor
Fair
Good
Excellent
Superior
13-19
<25.0
>41.9
20-29
<23.6
>41.0
30-39
<22.8
>40.0
40-49
<21.0
>36.9
50-59
<20.2
>35.7
60+
<17.5
>31.4
Male (values in ml/kg/min)
Age
Very Poor
Poor
Fair
Good
Excellent
Superior
13-19
<35.0
>55.9
20-29
<33.0
>52.4
30-39
<31.5
>49.4
40-49
<30.2
>48.0
50-59
<26.1
>45.3
60+
<20.5
>44.2
Table Reference: The Physical Fitness Specialist Certification Manual, The Cooper Institute for Aerobics Research, Dallas TX, revised 1997 printed in Advance Fitness Assessment & Exercise Prescription, 3rd Edition, Vivian H. Heyward, 1998.p48

30. VO2 Max in Athletes and Non-Athletes
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VO2 Max in Athletes and Non-Athletes
Energy Systems
VO2 max varies greatly between individuals and even between elite athletes that compete in the same sport.
In previously sedentary people, training at 75% of aerobic power, for 30 minutes, 3 times a week over 6 months increases VO2 max an average of 15-20%

31. Woodland Christian High School
Improving VO2 Max
Energy Systems
Genetics plays a major role in a person’s VO2 max and heredity can account for up to 25-50% of the variance seen between individuals. The highest ever recorded VO2 max is 94 ml/kg/min in men and 77 ml/kg/min in women. Both were cross-country skiers
The extent by which VO2 max can change with training also depends on the starting point. The fitter an individual is to begin with, the less potential there is for an increase and most elite athletes hit this peak early in their career. There also seems to be a genetic upper limit beyond which, further increases in either intensity or volume have no effect on aerobic power. This upper limit is thought to be reached within 8 to 18 months.

32. VO2 Max as a Predictor of Performance
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VO2 Max as a Predictor of Performance
Energy Systems
In elite athletes, VO2 max is not a good predictor of performance. The winner of a marathon race for example, cannot be predicted from maximal oxygen uptake.
Perhaps more significant than VO2 max is the speed at which an athlete can run, bike or swim at VO2 max. Two athletes may have the same level of aerobic power but one may reach their VO2 max at a running speed of 20 km/hr and the other at 22 km/hr.
While a high VO2 max may be a prerequisite for performance in endurance events at the highest level, other variables such as anaerobic threshold are more predictive of performance.

33. Woodland Christian High School
Oxygen Deficit
Energy Systems
While exercising intensely the body is sometimes unable to meet all of its energy needs.  Specifically, it is unable to take in and absorb enough oxygen to adequately 'feed' the muscles the amounts of energy needed to adequately perform the tasks the athlete is requesting from the body. 
In order to make up the
difference without sacrificing
output, the body must tap into
its anaerobic metabolism. 
This where the body uses both
aerobic and anaerobic energy
production. While not hugely
detrimental, oxygen deficits
can grow to a level that the anaerobic energy system cannot cover.  This can cause performance to deteriorate.

34. Woodland Christian High School
Oxygen Debt
Energy Systems
Oxygen debt refers to post exercise oxygen consumption where the body needs to pay back its debt incurred above after the exercise is over
You will notice that even after you are done racing you will continue to breath hard. 
At this point your body is still trying to repay the oxygen debt that was created when you were working hard.

35. Effects of Training on the Aerobic System
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Effects of Training on the Aerobic System
Energy Systems
The performance of any activity requires a certain rate of oxygen consumption. A person’s ability to perform an activity is limited by their maximal rate of oxygen consumption; Therefore, the most efficient method for improving the aerobic energy system is endurance training/exercise.
Long, slow distance training or exercise at the low end of your target heart rate tends to use slow twitch fibres.
Walking, jogging or any other light exercise, uses mainly slow-twitch fibres to do the work. ST fibres are slower to fatigue and are well suited for endurance activities.

36. Effects of Training on the Aerobic System
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Effects of Training on the Aerobic System
Energy Systems
Endurance exercise consists of repeated, sustained effort of long duration several times per week;
Generally, the higher the intensity, the greater the oxygen consumption. When exercising the target heart rate (THR) should be raised to 70% of max. Examples include:
running, swimming or biking for 40 minutes or more at a heart rate of bpm
Notes: A highly trained or elite athlete should be able to sustain a heart
rate of 85% of their VO2 max.
This type of training does not raise your anaerobic threshold.

37. Effects of Training on the Aerobic System
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Effects of Training on the Aerobic System
Energy Systems
Endurance training has four major effects on the aerobic system:
Improved delivery of oxygen and nutrients to the muscles
Increase the size and number of mitochondria in muscle fibres
Increased activity of enzymes involved in the aerobic pathway
Preferential use of fats over glucose during exercise which saves the muscles limited store of glycogen

38. Using the Systems Together
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Using the Systems Together
Energy Systems
While running at a comfortable pace you use both systems, but the anaerobic - aerobic ratio is low enough that the lactate generated is easily removed, and doesn't build up.
As the pace is increased, eventually a point is reached where the production of lactate, by the anaerobic system, is greater than its removal. The anaerobic threshold is the point where lactate (lactic acid) begins to accumulate in the bloodstream.
Note: Depending upon the distance, and effort,
the body can use different proportions of
both of these systems. For example, the
800 m race is too long to be a sprint, but
too short to be a distance race. Therefore,
it is run at the cross-over between the
aerobic and anaerobic systems.

39. Training the Systems Together
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Training the Systems Together
Energy Systems
The best method to train all of the systems together is interval training. Interval work consists of repeating a series of short, high intensity, runs alternating with rest (recovery) periods.
Whichever interval training method is used, the athlete must continually push themselves into a state where lactic acid builds, forcing their body’s to adapt.
Regardless of the race distance you are training for, 5k or marathon, interval work will help you run faster.

40. Woodland Christian High School
Interval Training
Energy Systems
Pushing the body past the 'comfortable' speed of running increases aerobic capacity, trains the fast twitch muscles to operate at a higher/faster level and makes the athlete more tolerant of lactic acid build up.
The result of interval training is that a runner who can comfortably run a six-minute/mile pace and runs their intervals at a five-minute/mile pace will be able to increase their steady comfortable pace under an six-minute/mile pace.

41. Roles of the Three Energy Systems in Competitive Sport
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Roles of the Three Energy Systems in Competitive Sport
Energy Systems
Energy
Pathways
Anaerobic Pathways
Aerobic Pathways
Primary Energy Source
ATP produced without the
presence of oxygen
ATP produced with the
Energy System
Immediate Alactic
Short-term Lactic
Long-term Oxygen
Fuel
ATP and CP
Glycogen + glucose
Glycogen, glucose, fat and protein
Duration
0s s s s min 6 min min hr hr hr
Sport Event
Sprinting
100 m dash
Throwing
Jumping
Weightlifting
Ski jumping
Diving
Vaulting in Gymnastics
Track m
500m Speedskating
Most gymnastics events
Cycling (track)
50 m swim
100 m Swim
800 m track
Gymnastic floor exercise
Alpine skiing
Cycling 1000 m pursuit
Middle distance track, swimming, speedskating
1000 m canoe
Boxing
Wrestling
Rowing
Figure skating
Cycling, pursuit
Long Distance track swimming, canoeing, speedskating
Cycling
road racing
Marathon
Triathlon
Most team Sports/Racquet Sports

42. Summary Energy Systems Woodland Christian High School Energy System
Anaerobic Alactic
Anaerobic Lactic
Aerobic
Type of Activity
short sprints used in
baseball, pole vault
long jump triple jump
games such as football, basketball hockey
long distance running
cross country skiing
swimming
Range of Maximum Work Times
0 – 10 seconds
10 to 60 or 120 seconds (depending on conditioning)
120 seconds plus
Oxygen Required
None
None or very little
Yes
Lactic Acid Produced
Yes, accumulated faster than it can be removed
Depends on intensity
Energy Source
Chemical energy stored
in muscles, ATP and CP
Entirely carbohydrate
Mixture of fat and carbohydrate
End Products of Fuel Breakdown
Adenosine Diphosphate
Creatine Phosphate
plus energy
Lactic Acid
CO2 and H2O
Muscle Fibre Recruited
Fast and slow twitch
Predominately fast twitch
Slow twitch and
some fast twitch
Work Output per Unit of Time
High
Medium
Low

43. Endurance training can significantly improve the aerobic system
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Summary
Energy Systems
Energy for muscular activity depends on a supply of ATP that can be broken down into ADP and phosphate
All of the body’s biochemical processes and the three energy systems require ATP
Trained individuals are able to use ATP and remove lactic acid more efficiently than untrained individuals
Endurance training can significantly improve the aerobic system

44. Example of Interval Training
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Example of Interval Training
Energy Systems
Anaerobic Alactic Capacity/Power (sprints):
E:P ratio 1:3-6, >130%Vo2 max. 5-30sec. work.
Time Phase - maintain all year  10 x m strides, 90-95% effort. Jog return recovery. 2.  5 x 4 x 100m strides, % effort, 2min./4 min. recovery. 3.  6-10 x 20-30m hills, max effort, 1 1/2-2 min. recovery.