A2 Physical Education The Recovery process Oxygen debt & deficit O2 requirement O2 deficit Oxygen consumption Steady state O2consumption EPOC/Oxygen debt Resting O2 consumption Start Exercise End Exercise End Recovery Oxygen debt & deficit HR does not immediately return to its normal resting value. It is elevated to help the body return to its pre-exercise state This process is known as recovery. The old term for this elevated HR was Oxygen Debt, as it was thought that you had to pay back the oxygen that you borrowed. This analogy is not quite accurate and more up-to-date terminology is required to explain the process of recovery. Oxygen deficit It takes the aerobic system a little while to provide energy for muscular work, even at low intensities. During this time, the anaerobic processes must provide energy. Oxygen deficit can be thought of as the extra amount of oxygen that would be needed to complete the entire activity aerobically. The extra oxygen that the body takes in after exercise is known as: Excessive post-exercise oxygen consumption (EPOC) The Recovery process When you cease to exercise your HR begins to drop very quickly, but its recovery begins to slow down very gradually. This caused researchers to formulate the idea that recovery takes place in two stages: The fast immediate stage A slower longer stage. Alactic debt (the fast stage) During this stage the energy provided by the elevated metabolism is used to help the PC system recover. It takes approximately: 3 mins for the PC stores to fully replenish. 30 secs for 50% recovery. This process requires approximately 4 litres of oxygen. Myoglobin Myoglobin is a protein molecule similar to haemoglobin, that helps with the transport of oxygen. It is found within the muscle sarcoplasm and helps to transfer the oxygen from the blood supply to the mitochondria, where it is needed to fuel aerobic metabolism. It has a higher affinity for oxygen that haemoglobin. It takes approx. 0.51secs to replace the oxygen stored in myoglobin and the process takes 1-2 mins. During recovery, with elevated ventilation and HR there is a surplus of oxygen available for this to occur. Lactic debt (the slow stage) Lactic acid is removed from the body. It can take as long as an hour for all of it to be removed. Lactic acid can be removed in 4 ways: 60% is converted back to pyruvic acid and enters the Kreb’s Cycle; it is used in aerobic metabolism It can be coverted back to glucose (a process known as gluconeogenesis that takes place in the Cori Cycle) It can be converted into proteins It can be removed via sweating and in urine. Removal of CO2 The increased concentration of CO2 formed as a waste product from the aerobic system has to be removed from the body. The majority of CO2 (70%) is removed in the plasma of the blood by forming carbonic acid. Chemoreceptors detect levels of CO2 /low pH and stimulate the cardiac and respiratory control centres. Hence, both cardiac output and respiratory rate remain higher during recovery to expel the CO2 from the lungs. Replenishment of glycogen stores Following exercise, glycogen stores in the liver and muscles will be depleted. The only way to replenish these stores is through ingestion of CHO. Often this is through eating, but some athletes have to take glucose solutions intravenously to replace it more quickly. It can take about 48 hours with a high CHO meal to totally restore glycogen after a heavy bout of training. Implications of recovery for planning training sessions. The restoration of PC is very rapid and full recovery only takes 2-3 mins. If speed work is the specific objective of the training session, sufficient recovery time should be allowed to ensure full recovery. Use an active cool-down during recovery time. Removal of lactic acid is considerably quicker Moderate intensity (35% of VO2 max) seems to be most beneficial Monitor training intensities so that OBLA can be avoided and the quality of training maintained. Warm up thoroughly before training. This will help reduce oxygen deficit by increasing the oxygen supply to the working muscles and ensure myoglobin stores are full.