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Fatigue and recovery mechanisms. Fatigue. Exercise induced reduction in the power-generating capacity of a muscle and an inability to continue activity is defined as fatigue. Fatigue. The onset and rate of fatigue depends on; Intermittent or continuous activity
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Fatigue • Exercise induced reduction in the power-generating capacity of a muscle and an inability to continue activity is defined as fatigue.
Fatigue • The onset and rate of fatigue depends on; • Intermittent or continuous activity • Slow or fast twitch fibres (slow are more fatigue resistant) • Isotonic, isometric or isokinetic muscle contractions (isometric cause fatigue fastest) • Intensity and duration of activity • Level of fitness and training of the athlete
Multifactorial fatigue • Fatigue is multifactorial, meaning it is usually more than 1 factor causing the fatigue • Fill in the table using page 147 of your text
Lactic acid • Read pages 148-151 of your textbook. • Take notes from page 148/149 and copy down the lactate shuttle model. • Answer Qs 1-5
Oxygen deficit • As we start to exercise and move from rest, there is a period of time which the body’s oxygen demand exceeds the supply of oxygen from its system. • Oxygen deficit is the amount by which the oxygen supply fails to meet oxygen demand. • During this time the body must obtain most of its ATP anaerobically
Steady state • Steady state is attained when the oxygen supply equals the oxygen demand. • On an oxygen consumption graph, steady state is represented by a plateau.
Oxygen debt or EPOC • At the completion of exercise, the demand for ATP decreases dramatically. However the amount of oxygen consumed still remains above amounts required at resting level. This is called EPOC (excess post exercise oxygen consumption). • Exhausting high intensity anaerobic exercise results in a larger oxygen debt than exercise at lower intensities and work loads
Elevated body temperature • As core temperature rises, sweat rates increase and blood is redistributed to the skins surface to maximise evaporative cooling. • Therefore less blood, oxygen and fuels flow to working muscles. • To counteract decreases in blood plasma volumes, both HR and CO must increase to continue supplying the same amount of oxygen to working muscles.
Elevated body temperature • Sweating • Copy out the did you know on page 160. How does this relate to chapter 4?
Recovery strategies: Refuelling • ATP PC restoration Why would having a high aerobic capacity help with the restoration of the ATP PC system?
Recovery strategies: refuelling • Glucose restoration • Muscles can store greater amounts of CHO in the hours following exercise, so high GI foods should be consumed as soon as practically possible to ensure rapid refuelling.
Metabolic by-products: H+ ions • The more quickly H+ ions can be removed from muscles, the more quickly performers will recover. • An active recovery; • maintains higher oxygen levels • creates ‘muscle pump’ • prevents venous pooling. - Write a definition for muscle pump and venous pooling.
Recovery strategies: lowering body temperature • Apart from hydration (before, during and after activity), strategies for cooling to maintain optimal core temperature include; • contrast bathing • cold showers • ice vests • cool rooms • fans/shade/modified clothing
Review questions • List two functions of drinks that contain electrolytes (sports drinks)? • Athletes who perform high intensity efforts as part of their role in a team sport ( such as soccer, football or basketball) often undertake an active warm down. Discuss the effect this has on oxygen debt and how this assists recovery.
