Figure 4.

Skeletal muscle and mitochondrial phenotype differences between endurance and sprint sports. Endurance sports consist of long-distance exercise at low speeds. The muscle fiber phenotype is characterized by a greater abundance of type I (slow, pink) and IIa (fast, green) oxidative fibers, which together may provide less contractile power but contain more mitochondria and a higher oxidative capacity. Conversely, sprint sports utilize short-distance exercise at high speeds. The muscle fiber phenotype is characterized by a greater abundance of type IIx (fast non-oxidative, yellow) fibers, which may provide greater contractile power but contain less mitochondria and a lower oxidative capacity. Comparative mitochondrial phenotype related to these two skeletal muscle phenotypes has not yet been fully described. Created with Biorender.com.