Energy Transfer During Exercise
The Energy Systems
Energy Sources From Food:
CHO = 4 kcal Fat = 9 kcal Pro = 4 kcal
For Exercise: ATP > ADP + P
Methods of Supplying ATP For Energy Stored ATP CP or ATP-CP Anaerobic
metabolism/glycolysis/lactic acid system
Aerobic metabolism
ATP-PC System Intramuscular phosphagens Short anaerobic Uses stored ATP Strength/power movements Replenishes
Lactic Acid System Glycolytic Long anaerobic Burns glucose Accumulates lactate at high
intensities Muscular endurance activities
Blood Lactate Threshold Exercise intensity at
the point of lactate buildup.
Predicts aerobic exercise performance.
Untrained ~ 55% of VO2 max.
Trained ~ 75% of VO2 max.
Aerobic System Oxidative Burns fatty acids Long-term energy Better butter burner Cardiorespiratory endurance
activities
Energy SystemsATP-PC Glycolysis Beta
Oxidation
Stored ATP allows for 3-5 sec. of activity
Breakdown of glucose – end result is pyruvate
Breakdown of triglyceride – yields ATP
ATP-PC used up in 10-15 sec. of activity
Converted to lactic acid if anaerobic envir.
> Fat oxidation = better butter burner
The Energy-Time Continuum
0
20
40
60
80
100
120
10 453:
45 14 135
Work Time
% o
f ene
rgy
from
aer
obic
As the work time increases, the percentage of energy contributed by the aerobic system increases.
Oxygen Uptake During Aerobic Exercise Increases sharply
at onset Levels off within a
few minutes if pace is constant (steady state)
Oxygen demand met by supply
Maximal Oxygen Uptake (VO2 max)
The region where oxygen uptake plateaus and does not increase despite an additional increase in exercise intensity.
Maximal Oxygen Uptake Affected by body size: larger size
means larger VO2 max. Absolute oxygen uptake (ml.min.) Relative oxygen uptake
(ml.kg.min.) Relative to body mass
Oxygen Deficit Difference between
oxygen consumed during exercise and amount that would have been consumed had a steady rate, aerobic metabolism occurred at onset of exercise.
Oxygen Deficit:Trained vs. Untrained Trained reach steady rate quicker Higher total oxygen consumption Less reliance on anaerobic
glycolysis Lower deficit in trained individuals
due to: Earlier aerobic ATP production Less lactate formation
Excess Post-Exercise Oxygen Consumption (EPOC) Formerly called oxygen debt Excess oxygen above the resting
level in recovery Most lactate does not synthesize
into glycogen as originally thought Heart, liver, kidneys, and skeletal
muscle use lactate as energy substrate during recovery
Active Recovery for Heavy Exercise Facilitates lactate removal because
of: increased perfusion of blood through
the liver and heart increased blood flow in muscles
because muscle tissue oxidizes lactate during Krebs Cycle
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