Fatigue and recovery mechanisms

Fatigue and recovery mechanismsFatigueExercise induced reduction in the power-generating capacity of a muscle and an inability to continue activity is defined as fatigue.FatigueThe onset and rate of fatigue depends on;Intermittent or continuous activitySlow or fast twitch fibres (slow are more fatigue resistant)Isotonic, isometric or isokinetic muscle contractions (isometric cause fatigue fastest)Intensity and duration of activityLevel of fitness and training of the athleteMultifactorial fatigueFatigue is multifactorial, meaning it is usually more than 1 factor causing the fatigueFill in the table using page 147 of your text

Fuel depletionMetabolic by productsNeuromuscular eventsElevated body temp1.2.3.4.1.2.3.4.1.2.1.2.3.1

Lactic acidRead pages 148-151 of your textbook.Take notes from page 148/149 and copy down the lactate shuttle model.Answer Qs 1-5

Oxygen deficitAs we start to exercise and move from rest, there is a period of time which the bodys 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 anaerobicallySteady stateSteady 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 EPOCAt 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

Fuel depletion and recoveryPredominant energy systemLikely causes of fatigueTypes of recoveryATP PC

Anaerobic glycolysis

Aerobic system

Elevated body temperatureAs 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 temperatureSweating

Copy out the did you know on page 160. How does this relate to chapter 4?

Recovery strategies: RefuellingATP PC restoration

Why would having a high aerobic capacity help with the restoration of the ATP PC system?Passive recovery timeMuscle PC restored30 seconds60 seconds90 seconds120 seconds150 seconds180 seconds10 minutesRecovery strategies: refuellingGlucose restorationMuscles 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+ ionsThe more quickly H+ ions can be removed from muscles, the more quickly performers will recover.An active recovery;maintains higher oxygen levelscreates muscle pumpprevents venous pooling.- Write a definition for muscle pump and venous pooling.

Recovery strategies: lowering body temperatureApart from hydration (before, during and after activity), strategies for cooling to maintain optimal core temperature include;contrast bathingcold showersice vestscool roomsfans/shade/modified clothingReview questionsList 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.Review questions