1. MODULE 4: ENERGY SUBSTRATES
USED DURING EXERCISE
• EFFECT OF EXERCISE
INTENSITY AND DURATION
• AEROBIC AND ANAEROBIC ACTIVITIES

2. ENERGY SYSTEMS
ANAEROBIC

3. PHOSPAGEN / ATP-CP SYSTEM
• ATP (Adenosine Triphosphate) is stored in all cells, particularly
muscles
• It is free energy, body makes it available for immediate use, needs
recovery time to restore the storage
• Great for short and quick activities, because it only last for about 5
seconds.
• Activities like-- 10 metre sprints, diving, spiking and throwing the
shot.
• When ATP is used it breaks down into ADP. ADP then can combine
with phosphocreatine (PC) to make more ATP, but only for a short
period of time around 5-20 seconds.
• These two systems combine for activities like 200m sprints and
sports where short intermittent burst of activity are required— for
example, basketball, hockey and rugby.

4. Notes
ATP (adenosine triphosphate) is the primary
molecule of energy for human movement. At
rest we have a small store of ATP, perhaps a
few seconds of intense performance worth.
This is replenished by another important
molecule, phosphocreatine or creatine
phosphate (PCr). Energy from this system is
supplied very quickly but lasts less than 10
seconds before it needs to be replenished
with res

5. LACTIC(LA) SYSTEM
• This system begins when phosphocreatine stores are deplete
• The body requires another ingredient-- muscle glycogen
(glucose) to be added to continue.
• Lactic acid (or lactate) comes from the breakdown of the
glucose released from the muscles.
• Outcome- Positive Hydrogen ions accumulate in the muscle
and cause it to fatigue.
• Sports that do repeat sprinting or high energy activities, such
as ice hockey, sprint cycling, 100m swim, lacrosse, soccer, up
to the 400 metres in track.

6. Notes:
Beyond the energy supply of the PCr system, and with continued
high-intensity activity, the lactic acid system takes over and
produces another supply of ATP, limited by the rate of oxygen
availability, for up to about 90 seconds depending on intensity and
lactate tolerance. This system will dominate in a 400 metre runner
or 100 metre swimmer for example, although most activities longer
than about 10 seconds use a mix of energy systems.
Glucose stored in muscle as glycogen is the main source of energy
substrate for this system. Performance can be limited by
inadequate storage of muscle glucose, or inhibition of the rate at
which it is made available. These two systems, alactic and lactic,
supply fast energy.

7. OXIDATIVE SYSTEM
• Using oxygen to fuel the breakdown of
carbohydrates first, free fatty acids second and
if the exercise continues long enough -protein.
• The aerobic system is more for moderate or low
intensity work, but of longer duration.

8. Notes
Oxygen supply maintains the aerobic system more or
less perpetually as long as a fuel source is available,
energy again being ultimately provided as ATP. The
aerobic system uses blood glucose, muscle glycogen,
blood fats, muscle triglycerides and even ketones
(breakdown of fats) — and proteins in certain
circumstances. Needless to say, this is the dominant
energy system of longer exercise duration and day-to-
day living. Understand, though, that a mix of fuel
sources and energy systems, including anaerobic
glycolysis (lactic acid system) will occur even in a
marathon or long bike race, in, say, acceleration up a
hill or a sprint finish.

9. http://btc.montana.edu/olympics/nut
rition/fuel06.html

10. Effect of exercise intensity and
duration - CARBOHYDRATE

11. Carbohydrate: High Power Fuel
• Fast ATP production
• Carbohydrate is the only energy substrate that
can produce ATP anaerobically
• More calories (kcal) provided per liter (L) of
oxygen consumed (5.01 kcal/L)
• Primary use by fast twitch muscle fibers
(recruited during high intensity exercise)

12. Effect of exercise intensity and
duration - FATS

13. Fat: Low Power Fuel
• Slow ATP production -- Fat can only produce
ATP via aerobic metabolism
• Fewer calories (kcal) provided per liter (L) of
oxygen consumed (4.65 kcal/L)
• Primary use by slow twitch muscle fibers
(recruited during low-moderate intensity
exercise)

16. ACTIVITY

18. Aerobic and anaerobic activities.
AEROBIC EXERCISE ANAEROBIC EXERCISE
Using the same large muscle group, Anaerobic activity is short in
rhythmically, for a period of 15 to duration and high in intensity.
20 minutes or longer while
maintaining 60-80% of your
maximum heart rate
Walking, biking, jogging, Racquetball, downhill skiing,
swimming, aerobic classes and weight lifting, sprinting, softball,
cross-country skiing soccer and football.

19. Examples of mild to moderate aerobic activities:
• Take a short walk around the block
• Rake leaves
• Play actively with the kids
• Walk up the stairs instead of taking the elevator
• Mow the lawn
• Take an activity break--get up and stretch or walk around
• Park your car a little farther away from your destination

20. Examples of higher intensity aerobic activities:
• Brisk walking, Jogging, Bicycling, Swimming
• Aerobic dancing
• Racket sports, Rowing
• Ice or roller-skating
• Cross-country or downhill skiing
• Using aerobic equipment (i.e., treadmill, stationary bike)

21. ACTIVITY