Energy Transfer in Exercise

1. Energy Transfer in Exercise

2. Immediate Energy • ATP-CP stored in muscle • sprints • heavy weightlifting • events < 10-15 seconds

3. Short-Term Energy • Lactic Acid • Anaerobic Glycolysis  LA • Intermediate energy source • Maximal intensity for 60-180 seconds • 400 meter run • 100 meter swim

4. Blood Lactate Concentration 25 50 75 100 Percent VO2 max Blood Lactate Concentration Untrained Threshold Untrained Trained Trained Threshold

5. Factors Related to Lactate Threshold • Low tissue O2 (hypoxia) • Dependence on glycolysis • Activation of FT muscle fibers • Reduced ability to remove lactate

6. Training the Lactate Threshold • Training can  threshold by 20-30% • genetics • training effect of producing less LA • training effect of more efficient LA removal

7. 20 15 Trained 10 Untrained 5 0 4 6 8 2 Exercise Time (min.) Long-Term Energy Oxygen Uptake (ml / kg-min)

8. Steady State/Rate • Initiation of Exercise • O2 uptake rises exponentially • Plateau is reached between 3-4 minutes

9. Oxygen Deficit • Quantity of O2 that would have been consumed had steady state been reach immediately

10. Oxygen Deficit • Endurance training  reach steady-state sooner  total O2 consumption is    anaerobic component

11. VO2max • With progressively demanding aerobic exercise, region where O2 uptake plateaus • Represents an individual’s capacity for aerobic resynthesis of ATP • Helps determine one’s ability to sustain high intensity exercise for longer than 4-5 minutes

12. Energy Spectrum

13. Energy Spectrum 100 Percent of Total Energy Yield 50 10 60 30 Maximal Exercise Time (minutes)

14. O2 Dept O2 requirement O2 deficit O2 Dept O2 Consumption Steady-state O2 consumption Resting O2 consumption Start Exercise End Exercise End Recovery Exercise Time

15. Classic O2 Dept (EPOC) Theory • Fast component – represents O2 required to rebuild ATP and CP • Slow component – removal of tissue lactate via conversion to glycogen or oxidation to CO2 and H2O

16. Contemporary EPOC Theory • Short duration, light to moderate exercise  • Recovery O2 serves to replenish high-energy phosphates (several minutes

17. Contemporary EPOC Theory • Longer duration, high intensity aerobic exercise  • Much longer period of O2 uptake • Some used for lactate  glycogen

18. Causes of EPOC following Heavy Exercise • Resynthesize ATP and CP • Resynthesize lactate to glycogen • Oxidate lactate in energy metabolism • Restore O2 to blood • Thermogenic effects of elevated core temp. • Thermogenic effects of hormones • Effects of  HR, ventilation, & other functions.

19. Recovery • Steady state aerobic exercise or 5 to 10 second bouts of maximal exercise  not lactate accumulation  recovery is rapid • Fast component

20. Recovery • Longer periods of anaerobic exercise  • Lactate accumulation • Fast and slow components

21. Recovery • Exercise at 50% of VO2max can be continued at steady-state w/o build up • At 60-75% of VO2max – no steady-state  lactate accumulates • Lactate removal is accelerated by aerobic exercise