In normal adult skeletal muscle, cell turnover is very slow. However, after an acute lesion or in chronic pathological conditions, such as primary myopathies, muscle stem cells, called satellite cells, are induced to proliferate, then withdraw definitively from the cell cycle and fuse to reconstitute functional myofibers.
Nguyen, H. N. T., Bertrand, M. J. M., Sterpin, C., Achouri, Y., & De Backer, O. R. Y. (2010). Maged1, a new regulator of skeletal myogenic differentiation and muscle regeneration. BMC Cell Biology, 11, 57. https://doi.org/10.1186/1471-2121-11-57