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exercise-induced fatigue
dec. capacity or inability to maintain a given force production or power output.
fatigue is multifactorial
fuel depletion, accumulation of metabolic by-products, thermoregulatory fatigue
Fatigue can be seen when:
inc. time taken to complete distance
dec. in distance covered in particular time
fuel depletion fatigue mechanisms
ATP
energy demand inc. = rate of ATP breakdown inc.
ATP depletion → dec. in power output.
CREATINE PHOSPHATE (CP)
ATP-CP system fatigue mechanism - working maximally.
ATP-CP sustain activity for 6-10s, CP will deplete rapidly.
when CP deplete → anagly system inc. contribution = slower rate of ATP being made than ATP-CP system = dec power.
CP depletion is slower in lower intensity activities that arent maximal.
RECOVERY STRAT
passive recovery via aerobic system. 3min 98%, 30s 70% CP
GLYCOGEN
occurs during sustained aerobic work in endurance events.
trained athletes can utilise fats for longer than untrained.
glycogen stores can sustain activity for 90min-2hrs. When it depletes, fats is main source (triglyceride)
trigly → slower rate than glycogen = fatigue = slow down performance
accumulation of metabolic by-products
ADP+PI → ATP-CP system
inorganic phosphate (Pi) accumulates during maximal-intensity work
Pi comes from CP splitting. Pi slows down muscle contraction = dec. force & power output
LACTATE & H+ → anagly system
incomplete breakdown of o2 = lactic acid → lactate & H+ ions
lactate shuttle to be fuel again, When H+ & lactate produced at faster rate than removed during high intensity → pH muscle changes = acidic = impair glycolytic enzyme → fatigue, slow down etc.
RECOVERY STRAT
active recovery for anagly system.
lactate inflection point (LIP)
final point where lactate production = lactate removal .
lip is passed = aerobic system cant remove lactate fast as produced = inc. contribution from anagly system → rise in blood lactate → accumulation of metabolic by-products & fatigue
higher LIP = Higher intensity athlete can work at aerobically
thermoregulatory fatigue
fatigue resulting from inability to maintain a stable body temp.
body temp to be constant → heat loos must match heat gain/produced
blood is used to regulate temp, blood redistributes heat via vasodilation to skin for radiation and evaporation.
in cool temps & short duration redistribution of blood flow is good
long duration, warm/high temp = large redis of blood flow to skin away from muscles → less o2 delivered to working muscles = cant do aerobic ATP = inc. contribution from anaerobic systems = accumulation metabolic by-products
body sweats to thermoregulate, sweat come from blood plasma.
lots of sweating = dec. blood plasma = inc viscosity of blood = dec. SV and inc. HR → heart pump harder to push thick blood = working hard no inc. in pace → fatigue.
dehydration from water loss → core body temp inc → affect enzyme → slower performance
nutritional and hydration strats
enhance performance, delay fatigue, optimise recovery.
CHO LOADING prior and during
prior
preload CHO to maximise body glycogen stores.
good for long duration events lasting 90min+
eat complex carbs → pasta
cho loading delays fatigue by extending steady state, using glycogen as fuel source → delaying the switch to fats (slower rate)
during
delays muscular fatigue
muscles provided additional fuels, maintains oxidation of carb fuel stores.
gels
muscles more responsive to insulin after activity and has highest glycogen uptake 30min. Take in cho to return to refuel muscle and liver glycogen stores.
protein and co-ingestion of cho and protein
protein → inc. rate of protein resynthesis, muscle rebuild & repair.
coingestion cho & protein
ENHANCES uptake of glycogen at muscles, recovering faster rate, enhances proteins synthesis
coingestion cho & water
enhance absorption rate of cho → faster restoration of muscle glycogen
hydration before, during, after
drink water to maintain blood plasma levels
drink water before to dec. thermoregulatory fatigue and amount of blood plasma lost
drink after to rehydrate liquid that has been lost as sweat.