1. ENERGY SYSTEM INTERPLAY

2. Aerobic Provides energy for long duration events. Uses oxygen and glycogen. Efficient producer of energy.

3. Anaerobic (Lactic Acid) Provides energy for events of 30-120 seconds. Does not use oxygen. Produces lactic acid.

4. ATP-CP Produces energy for events of 0-10 second duration. Does not use oxygen. Quickly exhausted.

5. Depending on the duration of the exercise, each energy system will contribute different amounts to the overall energy production.

6. Energy Systems Used During Select Activities

7. When an athlete trains, each energy system will become more efficient. Also, the transitions between the usage of each energy system is quicker. During many activities there is still some energy contribution from each system because even though they have been “used”, they continue to work in the background.

8. Why does it take events of approx. two minutes duration before the aerobic system takes over as the predominant supplier of energy? –Because it takes that long for the O 2 uptake and delivery systems to provide enough O 2 for aerobic glycolysis.

9. So…..What Happens When You Exercise? So imagine that you start running. Here's what happens: The muscle cells burn off the ATP they have floating around in about 3 seconds. The ATP-PC system kicks in and supplies energy for 8 to 10 seconds. This would be the major energy system used by the muscles of a 100-meter sprinter or weight lifter, where rapid acceleration, short- duration exercise occurs.

10. If exercise continues longer, then the glycogen-lactic acid system kicks in. This would be true for short-distance exercises such as a 200- or 400-meter sprint or 100-meter swim. Finally, if exercise continues, then aerobic respiration takes over. This would occur in endurance events such as an 800-meter run, 400m swim, marathon run, rowing, cross-country skiing and distance skating.

11. OXYGEN UPTAKE AND DELIVERY

12. Oxygen Delivery Respiratory and cardiovascular systems are responsible for the delivery of oxygen to the muscles. To ensure a steady, rich supply of oxygen to working muscles, it is desirable to have: –Large lungs –Large heart to pump increased volumes –Blood rich in RBC’s to carry O 2 –Lots of myoglobin in muscles to take O 2 out of blood

13. Oxygen Uptake VO 2 : –The body’s ability to take up oxygen for energy production.

14. Factors That Dictate VO 2 Heredity –lung size, muscle size, heart size, muscle fibre composition i.e. more slow twitch fibres Sex –women have lower VO 2 than men: have less haemoglobin smaller and less muscle mass more body fat

15. Age –VO 2 declines after the early 20s decline in cardio-respiratory efficiency increase in body fat people become more inactive. Body Fat –As excess body fat decreases, VO 2 increases. –In effect, excess body fat decreases VO 2.

16. Training –Research is undecided! Some people make huge improvements while others make little.

17. Uptake and Delivery During Exercise It takes approx. 2 mins for the oxygen uptake and delivery system to provide enough oxygen for the aerobic energy system to take over ATP production. Until then ATP is being produced anaerobically.

18. Aerobic Steady State When the uptake and delivery systems have ‘caught up’ with the demand for oxygen, uptake levels off. If an athlete puts on a burst of speed the oxygen demand will increase. The extra ATP required to increase pace comes from anaerobic sources.

19. If the pace is maintained, aerobic steady state will be higher. This process continues until a new steady state cannot be reached = VO 2 Maximum.

20. OXYGEN DEFICIT AND DEBT

21. Oxygen Deficit The shortfall between oxygen consumption at the onset of exercise and steady state. Some or all of the ATP required is produced anaerobically.

22. Oxygen Debt The ‘repayment’ of oxygen deficit with oxygen. Heart and breathing rates remain high to replenish CP and remove lactic acid.

23. We can sense or feel when we are in oxygen deficit because breathing is difficult and we feel ‘out of sorts’. We know we are ‘paying back’ oxygen debt when our breathing rate and heart rate remain high while we are in oxygen debt.

24. After exercise the amount of oxygen required depends on the size of the oxygen deficit. ATP production during oxygen deficit comes from the ATP-CP and lactic acid systems. Therefore, both of these systems need to be ‘paid back’ during oxygen debt.

25. Types of Oxygen Debt 1. Alactacid Debt: –Occurs when oxygen is consumed in early recovery to replenish ATP-CP systems. This occupies approx. 3 minutes of recovery. 2. Lactacid Debt: –Occurs when oxygen consumed in early recovery is used to remove lactic acid. Light exercise speeds up this process.

26. Reading the Graphs We can tell the points at which exercise intensity was increased by the ‘spikes’ in heart rate as intensity was increased. We see evidence of oxygen deficit and debt because we see increasing heart rate as intensity increases followed by a tapering out before intensity increases again (deficit). In recovery (11.45+) we see the debt being repaid.

27. When the exercise intensity is increased the ATP for muscular contraction comes from anaerobic sources i.e. lactic acid system. As intensity is increased on the treadmill the body turns to anaerobic sources for energy until the oxygen uptake and delivery system provides enough O2 to work aerobically. However, before this happens, intensity increases again. Lactic acid builds up to levels where intensity can no longer be increased.