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Energy Systems for Exercise. Energy Sources. From Food: CHO = 4 kcal Fat = 9 kcal Protein = 4 kcal For Exercise: ATP ADP + P + energy (for muscle contraction). Adenosine Triphosphate. Energy-carrying molecule found in the cells of all living things. - PowerPoint PPT Presentation
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Energy Systems Energy Systems for Exercisefor Exercise
Energy SourcesEnergy Sources
From Food:– CHO = 4 kcal– Fat = 9 kcal– Protein = 4 kcal
For Exercise: ATP ADP + P + energy
(for muscle contraction)
Adenosine TriphosphateAdenosine Triphosphate
Energy-carrying molecule found in the cells of all living things.
ATP captures chemical energy obtained from the breakdown of food molecules and releases it to fuel other cellular processes.
Cells require chemical energy for three general types of tasks: to drive metabolic reactions that would not occur automatically; to transport needed substances across membranes; and to do mechanical work, such as moving muscles.
Methods of Supplying ATP Methods of Supplying ATP For EnergyFor Energy
Stored ATP + PC (Creatine Phosphate) or ATP-PC
Anaerobic metabolism/ glycolysis/lactic acid system
Aerobic metabolism
ATP-PC SystemATP-PC System
Short duration (<10 secs) anaerobic
Uses stored ATPStrength/power movementsReplenishes rapidly
The ATP-PC systemThe ATP-PC system
Active at the beginning of all forms of activities
Especially important in high intensity exercises like weight lifting that require short bursts of energy.
The source of fuel for the ATP-PC system is ATP and PC that is stored in the muscles. Only a small quantity can be stored, so this energy source is only effective for activities that last ten seconds or less.
GlycolysisGlycolysis
Breakdown of carbohydrates for fuel Fuel stored in the muscle as glycogen /
delivered to the muscle as blood glucose
Glycolysis can produce fuel for 30 seconds to a minute for moderate heavy resistance training
Fast (Anaerobic) GlycolysisFast (Anaerobic) Glycolysis(The lactic acid system)(The lactic acid system)
Fast glycolysis is used when oxygen is in short supply.
Fast glycolysis results in the formation of lactic acid
An increase in lactic acid in the muscle can involve muscular fatigue and ultimately cessation of exercise.
Active Recovery from Active Recovery from Exercise (Cool down)Exercise (Cool down)
Facilitates lactate removal because of:– increased perfusion of blood through the
liver and heart– increased blood flow in muscles because
muscle tissue oxidizes lactate
Slow (Aerobic) glycolysisSlow (Aerobic) glycolysis(The aerobic system)(The aerobic system)
Slow glycolysis is used if there is enough oxygen to allow a continuous supply of fuel.
The byproduct of this form of glycolysis is pyruvate, which is not converted to lactic acid but is transported elsewhere.
Pyruvate is eventually dissipated as sweat/urine
Aerobic/Oxidative SystemAerobic/Oxidative System
Supplies energy to the muscle through the use of continuous oxygen transport.
System works at rest and during very low intensity exercise such as walking
This form of energy primarily utilizes fats (70%) and carbohydrates (30%) as fuel sources, but as intensity is increased there is a switch in substrate majority from fats to carbohydrates
Oxygen Uptake During Oxygen Uptake During Aerobic ExerciseAerobic 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 Maximal Oxygen Uptake (VO(VO22 maxmax))
The region where oxygen uptake plateaus and does not increase despite an additional increase in exercise intensity.
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 DeficitOxygen Deficit
Order of energy production Order of energy production
Initial energy comes form ATP stored in muscles about 2 seconds
Then the ATP-PC system about 10 seconds
Then the Lactic acid system about 1 minute
Then the Aerobic system 1minute onwards
The Energy-Time ContinuumThe Energy-Time Continuum
0
20
40
60
80
100
120
Work Time (Minutes)
% o
f en
erg
y fr
om
aer
ob
ic As the work time
increases, the percentage of energy contributed by the aerobic system increases.
Blood Lactate ThresholdBlood Lactate Threshold
Exercise intensity at the point of lactate buildup.
Predicts aerobic exercise performance.
Untrained ~ 55% of VO2 max.
Trained ~ 75% of VO2 max.