1. Fuel Sources & Exercise Metabolism

14. Table3.7 Major characteristics of the human energy systems ATP-PCrLactic Acid Oxygen Main energy sourceATP, PCrCHO Fat Intensity levelHighestHighLowerLowest Rate of ATP Production HighestHighLowerLowest PowerHighestHighLowerLowest ATP CapacityLowestLowHighHighest Endurance CapacityLowestLowHighHighest O 2 NeededNo Yes Track Event100 m200-800 m5,000 mUltra Time1-10 s30-120 s>5 minhours

15. Table 3.8 Percentage contribution of anaerobic and aerobic energy sources during different time periods of maximal work Time 10 sec 1 min 2 min 4 min 10 min 30 min 50 min 130 min Anaerobic Aerobic 85 15 70 30 50 30 70 15 85 5 90 2 98 1 99

16. Energy Stores In the Average Man Mass (lb) Energy (kJ) Energy (kcal) Rx Time (Min) Liver Glycogen 0.221,60040020 Muscle Glycogen 0.886,4001,60080 Blood Glucose 0.022160402 Fat23390,00093,0004,900 Protein18.75142,00034,0001,800

19. Some Possible Causes of Fatigue During Exercise Increased formation of depressant neurotransmitters –Increased serotonin levels Decreased levels of energy substrates –Phosphocreatine –Muscle glycogen –Blood-sugar level –Branched-chain amino acids

20. Fatigue Sites Cont’d Disturbed intracellular environment –Impaired calcium recycling Disturbed acid-base balance –Increased H + due to lactic acid Decreased oxygen transport –Decreased blood volume due to dehydration Increased core temperature –Decreased cooling due to dehydration Disturbed electrolyte balance –Increased or decreased concentration due to sweat losses and H 2 O replacement