Skeletal-muscle adaptations to endurance training (review)

Endurance training raises skeletal-muscle oxidative capacity: more and larger mitochondria (mitochondrial biogenesis, apparent within a few weeks), increased capillary density, more oxidative enzymes, a shift toward more oxidative (Type I and IIA) fibres, and expanded intramuscular glycogen and lipid stores. Together these raise the capacity for oxidative ATP resynthesis and fat oxidation, reducing reliance on glycolysis at a given pace. Strong.