Strength Gains
What accounts for 50% of early strength gains?
Learning Effect (untrained individuals often have a total of 25-100% increase in strength gains)
What type of training is likely to improve rate coding?
ballistic, rapid-movements (wall balls)
Strength-trained individuals can recruit larger motor units earlier for more force. This goes against what principle?
Size Principle: type I before IIa/x, to prevent fatigue
What does fiber hypertrophy allow for?
more storage of muscle glycogen (bigger muscle = more room)
What explains superhuman feats?
less GTO activity: muscles can generate more force
Why can strength increase without an increase in hypertrophy?
Neural adaptations: they account for the first 8-10 weeks
What type of exercise maximizes chronic hypertrophy?
- high velocity, eccentric (disrupts z-disk)
- high-rep with low-load to volitional fatigue
- low-rep with high-load to volitional fatigue
20 week heavy resistance training program
20-25g
Describe how protein synthesis changes during exercise and after.
1. Exercise: decreases synthesis, increases degradation
2. After: increases synthesis, decreases degradation
Name 3 neural adaptions that come with strength training.
1. motor unit recruitment
2. rate coding
3. reduced GTO (autogenic inhibition)
4. reduced antagonist co-activation
What type of training should be emphasized in youth?
- enjoyable - gradual progression
- good technique
- use principle of specificity
Athletes consume how much protein per kg body weight? How should they do it?
1.6-1.7g per kg body weight
small 20g protein every 2-3 hours (+carbs)
right after training = larger 25g
What hormone facilitates fiber hypertrophy?
testosterone
- natural through puberty
- synthetic allows a large increase in mass
Can fiber hyperplasia contribute to hypertrophy?
Yes, via satellite cell function
Name 3 adaptations to the neuromuscular junction. (hint...enhance the utilization of a NT)
1. more vesicles
2. more acetylcholine receptors
3. increased presynaptic neurons branching
4. fewer fibers per motor unit (more type I)
What type of training prevents detraining after goals are met?
Maintenance resistance program: maintain strength/1RM, reduce training frequency
What controls protein synthesis? What activates it?
mTOR for mRNA transcription; activated by muscle stretch (e.g., RT), insulin, & amino acids (leucine)
Name 3 hormones in hypertrophy. When are they elevated?
testosterone, growth hormone, IGF-I or insulin-like growth factor
post exerciseWhat are the major changes with immobilization after 6 hours? (2) first week? (2)
6: reduced protein synthesis + initiates muscle atrophy
week: decrease in size/atrophy, decrease NM activity (type I is affected most)
Name the 2 types of hypertrophy and explain them.
Transient hypertrophy - after an exercise bout (edema, gone within hours)
chronic hypertrophy - structural change in muscle (long term)
What conditions allow for muscle fiber type conversion?
- Cross-innervation (both directions)
- Chronic low-frequency stimulation (type II to I)
- Limited evidence: high-intensity treadmill or resistance training (possibly type I to type IIa)
How much protein should the elderly consume?
25-50g of protein
Name 3 mechanisms resulting in hypertrophy. (think cross-bridge)
- More myofibrils
- More actin, myosin filaments (sarcomeres)
- More sarcoplasm
- More connective tissue
Name 2 benefits of RT for the elderly.
- helps restore age-related loss of sarcopenia
- improves quality of life - health, ADLs, independence, decreases fall risk primarily dependent on neural adaptations