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36 Cards in this Set
- Front
- Back
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Voluntary Exercise Fatigue |
-failure to maintain the expected required output |
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Electrical Stimulation Fatigue |
-a decline in force production |
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Muscle Weakness Fatigue |
-failure to generate maximum force |
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Potential Mechanisms of Fatigue |
-lack of available energy -inhibition of ATPase -alteration in excitation-contraction coupling |
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Central vs Peripheral Fatigue |
Central - before NMJ Peripheral - after NMJ |
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Primary Sites of Fatigue |
ATP - imbalance is not a problem NMJ - not a primary Sarco and T-tubes - not a primary SR - Pi enters the SR to form CaPi which reduces the available Ca which develops muscle fatigue |
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High H ion concentration |
-decreases force of X-bridge -decreases force at a given Ca release -inhibits SR Ca |
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High inorganic phosphate (Pi) |
-acts directly on X-bridge to reduce the binding of actin and myosin |
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Type 1 Fibers |
-up to about 40% VO2 Max -dependent on a continuous supply of blood |
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Type IIa Fibers |
-40-75% of VO2 Max -fatigue resistant -rich in mito and rely on O2 delivery |
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Type IIx Fibers |
-at 75% or greater VO2 Max -low mito content -produce a lot of lactate |
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Ultra Short-Term Events |
-less than 10 secs -limited by fiber type amount and distribution and motivation -primary energy is PCr |
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Short Term Events |
-10-180 secs -primary energy is anaerobic glycolysis -uses fast-twitch fibers |
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Mod Length Events |
-3-20 mins -dependent of oxidative energy production -limited by CV system and mito content |
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Intermediate-Length Events |
-21-60 mins -dependent on lactate threshold and efficiency
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Long-Term Events |
-1-4 hours -limited by the muscle and liver's ability to supply glucose |
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Atmospheric Pressure |
-the force exerted on a surface by the weight of the air above |
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VO2 and altitude |
-primary cause for decreased VO2 Max is desaturation of arterial blood -the CV responses for submaximal work are negatively impacted -elevated sub max HR -at sea level Hb is at 98% saturation
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Heat Syncope, Cramps, Exhaustion, Stroke |
Syncope - fainting or loss of strength Cramps - muscle spasms Exhaustion - collapse from loss of fluids Stroke - final stage of exhaustion |
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Acclimation |
- comes from exercising in heat for 10-14 days - causes increased plasma volume and capacity to sweat |
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Factors Related to Heat Injury |
1) fitness 2) acclimation 3) hydration 4) environmental temps 5) humidity 6) metabolic rate 7) Wind |
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Wet Bulb Globe Temperature Guide |
Dry Bulb - ordinary measure of temp in shade Black Bulb - radiant heat in direct sunlight Wet Bulb - measure temp whose bulb is covered in wet wick |
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Increases in VO2 Max |
Following exercise: -using large muscle mass -for 20-60 mins -3-5 times per week -50-85% VO2 Max |
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Training induced increases in VO2 Max are due to? |
-adaptation in Q (delivery) and AVO2 Diff (extraction) |
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Stroke Volume Adaptations |
-increased EDV b/c of plasma volume -increased size of the left vent -maybe increased contractility -reduced resistance to flow by reduced sympathetic activity |
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AVO2 Adaptations |
-increased extraction from capillaries to mito B/c of : -increased capillary density -increased mito volume (not key factor) |
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Metabolic Adaptations |
-increased capacity to transport FA across membrane -increased surface area of mito -less reliance on CHO metabolism, increased fat oxidiation |
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Antioxidant Adaptations |
-training increases endogenous antioxidants |
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Decreased Lactate from Training |
Due to: -increased capacity to use fat -increased mito volume -increased H type of lactate dehydrogenase -increased [MCT1]
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Muscle Contraction During Training |
-increases mRNA and promotes protein synthesis -peaks 4-8 hrs post and returns to basal within 24 hrs |
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Primary and Secondary Signals |
Passive Stretching - IGF Free Ca - calmodulin Free Radicals - NFkB PGC-1 alpha - cellular energetics |
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Detraining following endurance training |
-initially (<12 days) due to decreased plasma volume -between 21-84 days it is due to decreased AVO2 difference |
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Resistance Training increases strength by: |
-nervous system (8-20 weeks) -increased muscle mass (years) |
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Hyperplasia vs -trophy |
Plasia - increased muscle fibers Trophy - increased CSA |
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Rate of Detraining |
-detraining is faster in endurance training rather than resistance |
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Resistance Detraining |
-much of the loss of strength is due to neural changes -muscular adaptations are retained for long periods of time |
