exercise physiology 3
TRANSCRIPT
Fuel for Exercising Muscle
Fuel for Energy
Energy
Source
Carbohydrate
Fat
Protein
CarbohydratePrimary source of energy
All carbohydrate is ultimately broken down to glucose or stored in the muscle or liver as glycogen
Dietary sources of starches and sugar to replenish carbohydrate reserve.
FATLarge source of energy during prolonged, less intense exercise.
Rate of energy release is slow.
Less readily available for cellular metabolism because it must be reduced from its complex form.
Protein Minor energy source
Utilized during severe depletion of the other macronutrients or during starvation.
It can be used to generate free fatty acids FFAs for cellular energy
Or converted to glucose through the process of gluconeogenesis.
It can supply 5 to 10% of the energy needed to sustain prolonged exercise.
Rate of Energy Release
Bioenergetics Phosphorylation
Anaerobic metabolism
Aerobic metabolism
Fuel for EnergyThree Energy Systems
Immediate (ATP – Phosphocreatine System)
Short Term (Glycolytic System)
Long Term (Oxidative System)
ATP – PCr System Simplest of the energy systems.
This process does not require oxygen, but it can occur in the presence of oxygen.
During the first few seconds of intense muscular activity (sprinting), adenosine triphosphate (ATP) is maintained at a relatively constant level as phosphocreatine (PCr) declines.
Combination of ATP and PCr stores can sustain the muscles energy needs for up to approximately 15 sec of an all out sprint.
Short term system
Liberation of energy through the breakdown of glucose.
Anaerobic glycolysis entails a complex process involving 10 – 12 enzymatic reactions for the breakdown of glycogen to lactic acid.
Does not produce large amount of ATP.
Predominates during early minutes of high intense exercise (all out sprint for 1 – 2 min).
Long Term System Most complex of the three system
Slow to turn on, but has a tremendous energy – yielding capacity
Primary method of energy production during endurance events.
Oxidation of Fat Triglycerides - major energy source
Lipolysis carried out by lipases
Beta Oxidation – Enzymatic catabolism of fat by the mitochondria.
FFA is cleaved to acetic acid
Oxidation of Protein
Gluconeogenesis
Conversion into intermediates (pyruvate / acetyl CoA)
Energy yielded approx. 4.1 kcal/g
Interaction of the three energy
systems Do not work independent of each other.
Each system contributes to the total energy needs of the body.
One system usually predominates, depending on the activity.
Running Event
Immediate Short Term Long Term
100 m 95 3 2
200 m 95 2 3
400 m 80 15 5
800 m 30 65 5
1,500 m 20 55 25
3,000 m 20 40 40
5,000 m 10 20 70
10,000 m 5 15 80
Marathon (42.2 km)
5 5 90
Percentage of Emphasis on the Three Metabolic Energy Systems in Training
For Various Running Events