[Myosin isoforms in human skeletal muscle and their transformation in ontogenesis]

In this paper the functional characteristic of the main mammalian skeletal muscle fibers and the current bases of their classification are presented. Ongoing changes in the various myosin heavy chain expression (MHCemb, MHCneo, MHC-I, MHC-IIa, MHC-IIx) occurring in the skeletal muscles during the development and ageing are described. The main factors determining the human muscle power generating capability in the ageing muscles are discussed. Moreover, a beneficial effect of the physical activity on the atrophy slowing process in the ageing muscles is presented.