Fatigue and Recovery

Defining fatigue How would you describe fatigue? “ A reduction in muscular performance or a failure to maintain expected power output” Muscular tiredness Shortness of breath Vary depending on activity

Causes of fatigue Insufficient ATP Lactic acid Glycogen depletion Fluid loss- low blood pressure

Recovery Process after Exercise Why does a 400m sprinter take the same deep breaths as a marathon runner after the race, even though they have run different distances? Why do we take deep breaths?

Recovery Process is needed to…. Rebuild muscular stores of ATP and PC that were used during exercise. Remove lactic acid. Replenish the myoglobin O2 stores (Myoglobin has an important, if small scale, role in carrying O2 from haemoglobin to the mitochondria thus ensuring the provision of energy in muscles. Complete restoration is thought to be complete by the time needed to recover the alactacid debt component. Replace Glycogen. There are many other processes involved in recovery. Processes such as restoration of cardiac/pulmonary functioning to resting values, return to normal body temperature etc. all require additional O2 ( although substantially less than that used during the alactacid and lactacid components) and therefore adds time to paying back the O2 deficit to reach the pre exercise level.

The oxygen debt Oxygen Debt= “the amount of oxygen consumed during recovery above that which normally would have been consumed at rest in the same period of time” Excess Post-exercise oxygen consumption (EPOC) =The need for O2 to rapidly replace ATP and remove lactic acid. Oxygen debt will occur if anaerobic activity has occurred Debt can be measured by analysing oxygen consumption before and after exercise. Oxygen debt used to compensate for oxygen deficit…..

Oxygen Deficit Oxygen deficit is the difference between the O2 required during the exercise and the O2 actually consumed during the activity O2 is not available for the first few mins approximately, so an oxygen deficit will always occur.

Oxygen debt has 2 components: 1=Alactacid Debt “It is the volume of oxygen required to restore phosphogens used in the alactic or ATP-PC energy system.” fast replenishment 1 st component of oxygen debt to be replaced 2-3 mins to replenish phosphocreatine 2-3 litres of 02 consumed to provide energy Intense work- this recovery process can occur to allow for another set of reps. Interval training doesn’t allow full recovery

Effects of training on the Alactacid Component Increased stores of ATP and PC in muscle cells. Improved ability to provide O2. Increase in size of alactic component

2= Lactacid Debt “ It is the volume of oxygen consumed during recovery used to remove lactic acid from muscles, which has accumulated during anaerobic work” slow replenishment Most lactic acid is -removed into blood - oxidised in mitochondria via aerobic system to give CO2 and H20 -converted into muscle and liver glycogen, glucose and protein -excreted from body as sweat or urine. Lactic acid removal takes approx 1 hour

The Effect of Lactic Acid Accumulation During high intensity exercise, muscle fatigue occurs at a pH of 6.4 and noticeably affects muscle function. It is thought that protons dissociate from lactic acid and associate with glycolytic enzymes, thus making them acidic. In this state, the enzymes lose their catalytic ability and energy production through glycolysis ceases. This coupled with the inhibition of the transmission of neural impulses impairs muscle contraction

Fate of the Lactic Acid 65% is oxidised to form carbon dioxide and water. 20% is converted back into glucose by the liver (gluconeogenesis). This is returned to the liver and muscles to be stored as glycogen. 10% is converted in the liver to form protein. 5% is converted into glucose.