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19 Cards in this Set
- Front
- Back
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gains in muscular fitness |
occurs after 3-6 months of resistance training
25-100% strength gain learn to more effectively produce force learn to produce true maximal movement similar as a percent of initial strength - young men experience greatest absolute gains vs. young women, older men, children due to incredible muscle plasticity |
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law of diminishing returns |
point of diminishing returns = not enough results and input to last point of negative returns = point in which results start to decrease with input |
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mechanisms of muscle strength gain |
1. hypertrophy vs. atrophy: increase muscle size = increase muscle strength decrease muscle size = decrease muscle strength 2. strength gains result from increase in muscle size and improved neural control |
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neural control |
no neural adaptations = no strength gain
(strength can occur without hypertrophy as it is a property of the neuromotor system, not just muscle) adaptations in motor unit recruitment, stimulation frequency, and other neural factors |
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causes of strength gain |
1) MU recruitment and synchronicity: greater #MU firing synchronus recruitment = strength gains facilitates contraction, produce more forceful contraction, improves rate of force development, increase capability to exert steady forces 2) increased rate coding frequency of MU discharge more rapidly reach a state of tetanus where peak force is developed |
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causes of strength gain pt 2 |
3) increased neural drive combination of MU recruitment and rate coding more efficient MU recruitment additional MU recruitment 4) autogenic inhibition inhibitory mechanism in the muscle prevents force development (golgi tendon organ) reduces inhibitory impulses and greater force production 5) other neural factors: reduced coactivation of agonists and antagonists |
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causes of strength gain pt 3 |
may result from greater MU recruitment - increase neural drive during max contraction increase frequency of neural discharge decrease inhibitory impulses |
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muscle hypertrophy |
increase in muscle size |
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transient hypertrophy |
after exercise bout edema formation from plasma fluid disappears within hours |
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chronic hypertrophy |
reflects actual structural change in muscle fiber hypertrophy and hyperplasia |
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fiber hypertrophy |
via: protein synthesis: exercise degrades the structural proteins of muscles after exercise: structural protein synthesis increases and degradation decreases increases myofibrils, actin and myosin filaments, sarcoplasm, and connective tissue facilitated by testosterone (natural anabolic steroid hormone) |
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fiber hyperplasia |
in cats: intense strength training causes fibre splitting, and each half grows to the size of the parent fiber in chickens, mice, rats: intense strength training causes only fibre hypertrophy difference due to training regimen humans: most hypertrophy due to fiber hypertrophy, but fiber hyperplasia contributes may only occur in certain individuals under certain conditions (depends on intensity/load) |
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neural activation and fiber hypertrophy |
increases in voluntary strength (substantial increase in 1RM) due to increased voluntary activation of muscle critical in first 8-10 weeks (important factor for short term increase in muscle strength) |
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atrophy and inactivity |
reduction/cessation of activity = atrophy; causes major changes in both muscle structure and function - immobilization studies: trained muscle suddenly becomes inactive - first 6 hrs of immobilization, rate of protein synthesis starts to decrease which initiates muscular atrophy due to lack of muscle use and consequent loss of muscle protein most dramatic within first week of immobilization (3-4%/day decrease in size and decrease in neuromuscular activity) type I more affected than type II - cross sectional area decreases and cell contents degenerate |
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detraining |
leads to decrease in 1RM (but can be regained in 6 weeks - either matches or exceeds previous 1RM) |
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fiber typer alterations |
type II become more oxidative with aerobic training type I become more anaerobic with anaerobic training occurs via: cross-innervation chronic low-frequency stimulation high intensity treadmill or resistance training type IIx --> type IIa transition common static strength increases cross sectional area percent type IIX decreases, percent type IIa increases |
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training and diet |
20-25 g of protein after resistance exercise for muscle growth 1.6/1.7 g protein/kg body weight/day for increasing muscle mass |
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age groups |
children and adolescents: resistance training safe with proper safe guards, children can gain both strength and muscle mass elderly: helps restore age related loss of muscle mass, improves health, helps prevent falls |
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strength training in older adults |
increases in strength dependent primarily on neural adaptations same (but blunted) response as in younger smaller increases in myofibrillar protein and muscle size 25-50 g protein necessary to stimulate mm protein synthesis |
