Presentation on theme: "Fatigue and Recovery Mechanism"— Presentation transcript:
1Fatigue and Recovery Mechanism Understanding of the multifactorial mechanisms (including fuel depletion, metabolic by products and thermoregulation) association with muscular fatigue, as a result of varied exercise intensities and durationsPassive and active recovery methods to assist in returning the body to pre-exercise levelsOxygen uptake at rest, during exercise and recovery, including oxygen deficit, steady state and excess post-exercise oxygen consumption
2Fatigue-Fuel Depletion The multifactorial mechanism of fatigue…… record some of the key words and messages in this clip.
3Fatigue…… is an exercise-induced reduction in the power-generating capacity of a muscle and an inability to continue the activity. …the onset and development of fatigue depends on the type, intensity and duration of activity, the muscle fibres being used the type of muscular contractions and the performers fitness levels.
4The onset is dependant on… Type: E.g. intermittent of continuousIntensity: E.g.Duration of activity:E.g.Muscle fibres being used:E.g.Type of muscular contractions:E.gPerformers fitness levels: E.g
5Classifying fatigue Fatigue can be classified as fuel depletion accumulation of metabolic by-productsneuromuscular interruptionselevated body temperature.But remember it is often multifactorial
6Fatigue is multifactorial (caused by a combination of many factors) Fuel DepletionNeuromuscular EventMetabolic By-ProductsElevated Body TemperatureList as many that you know in the boxes they belong in.How many can you think of?
7Fatigue is multifactorial (caused by a combination of many factors) Fuel DepletionNeuromuscular EventIntramuscular ATPDecrease in CNS firing (rate and intensity)PhosphocreatineImpaired sodium (Na+) and potassium (K+) gradientsMuscle GlycogenBlood GlucoseMetabolic By-ProductsElevated Body TemperatureH+ ions in plasma and musclesVery high core temperatureInorganic phosphateIncreased rates of dehydrationAdensine diphosphate (ADP)Redistribution of blood away from muscles to assist cooling=less blood/ 0Ca+
8Methods of generating ATP during muscle activity Table 6.3 (p.149)
9Lactic Acid- Good or Bad Read page 148Define the term DOMS, Lactate Inflection Point, Glycolysis, NAD +, acidosisWhat is one benefit of lactic acid?Explain the process of glycolysis with and without oxygenHow is it that triathletes have near resting levels of fatigue despite performing for hours?How is training beneficial in accelerating lactate clearance?How does lactate and acidosis effect muscle performance?Passive vs active recovery. What is better?
10Thinking things through… List the metabolic consequence of supplying ATP via the lactic acid system?How is it possible for triathletes to have near-resting levels of lactic acid despite performing for over a couple of hours?Explain how the accumulation of H+ is implicated in muscle fatigueWhy are lactate levels tested regularly during training sessions by physiologists, fitness advisors and coaches?Explain how aerobic training reduces lactate accumulation at any given workload and yet results in a greater level of lactate accumulation during maximal efforts.What is lactic acid buffering?
11Something else to consider… Study Figure 6.2. Explain the uptake of oxygen and oxygen deficit for an athlete 800m runner during an event lasting 2 minutesStudy figure 6.4. Explain the oxygen debt and its two parts, fast and slow.List the fast and slow process of EPOC
12Oxygen uptake during STEADY STATE EXERCISE Can you identify the location of oxygen deficit, steady state, oxygen debt (EPOC)?
13Define the following key terms Oxygen DeficitSteady State and PlateausOxygen debt or EPOCVO2VO2 MaxBufferingMyoglobinWorksheet
14LIP in terms of Steady State… The Beep Test CD comes with the ability to have students run 5 minutes at Level 6, 8, 10 etc......Rather than continuing with more rapidly occurring beeps. Most people can handled level 6, this is due to LIP not having been exceeded, there is energy system interplay, abundance of fuels.What would happen if you allow a 5 min break and then complete next 5 minute set. What does this mean in terms of LIP?Few students could sustain 5 minutes at level 10 – Once again, what is happening to lactate and therefore hydrogen accumulation? If students can keep up with this pace it’s clear they haven’t triggered LIP.
15Oxygen uptake with increasing workload What predictions can you make regarding this individual’s performance?
16Returning to a pre-exercise state High intensities = high EPOCEPOC has two stages; EPOC fast replenishment and EPOC slow replenishmentEPOC fast is primarily restoration of PC (taking 2-3 minutes)EPOC slow is primarily concerned with removal of lactic acid though bufferingSee table 6.5 (p.154) for a summary
17Likely Causes of fatigue Predominant ESLikely causes of FatigueTypes of recoveryATP-PCFuel depletion of ATP and PCPassive recoveryLactic AcidAccumulation of by productH+ ionsInorganic PhosphatesNon dietaryActive recoveryMassageHydo/water based therapiesAerobicFuel depletionGlycogen stores, then fatsElevated body temperatureCausing dehydration and blood flow away from musclesDietaryHigh GIRehydration via sports drinksNon-dietaryHydro/water based therapy
18Depletion of FuelOnly a factor when using the ATP-PC (PC depletion) and predominantly aerobic events lasting over 1 hourCHO is the only source of energy during maximal intensity exercise but fats are used increasingly during prolonged endurance eventsMuscle glycogen is the first fuel, as this is depleted, the muscles use glycogen stored in the liver, once this is depleted it looks towards blood-born fats and stored fats.The rate of energy production using glycogen is 50 to 100% faster that the production using fats. This is due to a more complex chemical reaction and great amounts of oxygen required. Small amounts of glycogen is needed to actually breakdown fats.Protein can be used but only in extreme circumstances lasting over 5 hours
19Carbohydrate and Fat utilisation during endurance events What would happen to the athletes performance once fat is the predominant energy source? Why?
20Metabolic By-products H+ ionsInorganic PhosphateThe negative effects on performance associated with lactate accumulation is due to the increase in hydrogen ionsThe breakdown of glucose or glycogen produces lactate and H+ (1 for 1)The hydrogen ions makes the muscle acidicAs the concentration increases the blood and muscles become more acidicThis acidic environment will slow down enzyme activity and the breakdown of glucose itselfDuring muscle contraction ATP is broken down to ADT and P1 (inorganic phosphate)Both are released during the cross bridge cycle of the sliding filament theory explaining muscle contractionsP1 is linked to the power stroke of the cross bridge cycleP1 accumulation occurs rapidly during high intensity exercise resulting in decreased contractile force productionP1 reduces the amount of Ca that can be released via the sodium-potassium pump and hence slows contractionADP is released near the end of the cross bridge cycle after the ATP split to release energyAccumulation of ADP causes a decrease in the maximal velocity of shortening in the cross bridge and an associated reduction in power output
21Neuromuscular Factors Decreased CNS ‘firing’The brain detects fatigue and acidosis so sends weaker signals to working muscles in an effort to reduce intensity and slow down the work rate of the musclesLess electrical stimulation created by sending fewer signmald eill result in less force and less frequent muscle contractionsThis is a self protection mechanism
22Elevated TemperatureIs only an issue while performing in environmental conditions of high heat an humidityNormal core temperature ranges from to 37.5 degree CelsiusHyperthermia is unusually high body temperature and elevated core temperature and severely affects performanceMuscles produce heat as they workOur bodies must loose this heat via radiation, conduction, convection and evaporationOnce the body looses 2-3% of it’s body weight through sweating, thermoregulation is impaired (the bodies ability to keep the core temp. within certain boundaries
23Physiological result of sweat loss- see fig 6.9 (p.160)
24Recovery StrategiesRecovery aims to return the body to pre-exercise conditions and reverse the effects of fatigue.Efficient recovery strategies will enhance adaptation to exercise loads as well as preparing the athlete for future training.Read pages Summarise the following recovery strategiesRefuelling: Phosphocreatine, muscle glycogen and blood glucoseMetabolic by-product: Removal of H+ ions in plasma and muscles and replenishing inorganic phosphate (Pi) and Adenosine diphosphate (ADP)Addressing neuromuscular factors.Lowering body temperature.
25Active vs Passive Passive PC Active Dietary refueling and hydration Removal of H+ ionsRebounding P1 to ADPAddressing nueronmuscular factorsStrategies for coolingPassivePC
27Application Tasks1. Work the Web: Review of Sports Drinks on the Market (p.166) Record Key Findings of the study. 2. Follow the following link to investigate the number of ways the AIS promotes performance recovery. Record Key findings 3.Investigate Strategies for cooling . Record Key findings 4. Student directed presentation on chosen fatigue management strategy E.g. Compression garments, hydration, ice baths, etc! Explain the scientific theory that underpins your chosen method