Skeletal muscle mass, muscle fibre numbers per muscle, muscle fibre size, strength and the trainability of these factors all vary greatly in the general population. Twin studies suggest that probably more than 50% of this variation is explained by genetics. Genome-wide association studies in humans and gene manipulation experiments in mice have identified gene variants that affect muscle mass or function. In mice, the gain or loss-of-function of at least 47 genes significantly increase muscle mass by in-between 5 and 345%. In humans, a genome-wide association study has identified 16 loci (regions in the genome) that are associated with grip strength. Together this suggests that the large variation of muscle mass and function depends on probably hundreds of DNA variants or more. It also explains why baseline levels of muscle mass and function and their trainability vary widely in-between humans.     «

Skeletal muscle mass, muscle fibre numbers per muscle, muscle fibre size, strength and the trainability of these factors all vary greatly in the general population. Twin studies suggest that probably more than 50% of this variation is explained by genetics. Genome-wide association studies in humans and gene manipulation experiments in mice have identified gene variants that affect muscle mass or function. In mice, the gain or loss-of-function of at least 47 genes significantly increase muscle ma...     »