why does muscle bulk increase as a result of some physical activity but not as a result of all physical?
- gardengallivantLv 76 years agoFavorite Answer
In some cases vigorous activity will induce mitochondrial biogenesis in muscle tissues along with tissue growth.
It depends on how vigorous the new activity is relative to the previous levels of activity and if there is excess weight being lost. A moderate increase in activity combined with weight loss produces a change in the mitochondria already present.
The first change is an increase in the mitochondrial working surfaces; their cristae, folds on the inner surface, increase and the organelle swells in size. This allows each mitochondria to do more work.
Once the mitochondria's full potential is reached and the level of activity still is placing a demand, then there will be mitochondrial biogenesis in the skeletal muscle and tissue growth triggered by the stress. Skeletal muscle mitochondria become very extensive and branch into spaces between the muscle fibers. They are shaped and positioned to support the muscle function as it increases.
- BP-LOLv 46 years ago
In isometric contractions or exercises the force exerted do not produce movements. Such exercises are done for body building. The muscle fibres increase in diameter which in turn increases the muscle mass. Weight lifting, bench press etc. are isometric exercises that produce more muscle mass.