We know that exercise promotes the increase of skeletal muscle.
But what increases: the number of cells in the muscle or the volume of existing cells?
Physical activity stimulates existing skeletal muscle cells to produce new myofibrils, which causes an increase in cell volume and consequently muscle.
In the adult individual, skeletal muscle cells no longer divide. However, there are special cells, called satellites, which are mononucleated and small and are located in the connective surrounding myocytes.
In very special situations, when the muscle is subjected to intense exercise, these cells can multiply and some of them fuse with existing muscle fibers, also contributing to muscle growth.
At satellite cells are important in skeletal muscle regeneration processes when injuries occur.