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Types of Movement. strength - greatest amount of force muscle can produce in single effort power - rate of force generated endurance - ability to perform repeated submaximal contractions flexion and extension abduction and adduction rotation. Types of Contraction.
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Types of Movement • strength - greatest amount of force muscle can produce in single effort • power - rate of force generated • endurance - ability to perform repeated submaximal contractions • flexion and extension • abduction and adduction • rotation
Types of Contraction • isometric tension causes no change in length • fibers shorten internally • countered by antagonist • ex: cutting horse poised • concentric • muscle shortens as it generates tension • ex: flexor or extensor
eccentric • muscle lengthens as it generates tension • used to resist force • ex: flexor to control extensor and stabilize joint • muscles develop greatest tension with eccentric contraction • more soreness • downhill work • drop fences • collected frame
Recruitment of Muscles • affected by gait, speed, and duration of exercise • change gait • use different muscles • change speed • recruit more fibers for increases force • controlled by nervous system • fibers vary in their sensitivity to impulse
walk • mostly ST fibers • only 10% of total fibers needed • trot • ST and FOG • trot about 30 - 50 % fibers recruited • canter • more FG fibers recruited • gallop (full out) • 100 % fibers recruited
Effects of Conditioning • changes structure and chemical composition of fiber • twitch type does not change ( ST vs. FT ) • hypertrophy - muscle growth • increases size and weight • unfit - 42% of BW • fit 50 % BW • chemical effects • increase enzyme levels • increase amount of energy substrate stored • affects vary with intensity, duration, and frequency of regular exercise
endurance training • increase aerobic capacity • increase in aerobic enzyme activity • shift in preference of substrate use (fats) • increase number of oxidative fibers (FG to FOG) • rapid increase - first 2 months of training • increase volume density of mitochondria • increase capillary density • decrease speed and power • decrease fiber diameter • slow adaptation - several months • more efficient use of ATP with O2 • increase speed at which VLa4 occurs
sprint training (anaerobic) • increase power • increase diameter of glycolytic fibers • maximum force generated is proportional to cross sectional area • increase number actin and myosin myofibrils • increase amount of connective tissue • decrease aerobic capacity • decrease number capillaries for fiber area • improve buffering capacity in muscle fiber • delay decrease of pH