Exercise-mediated angiogenesis

Skeletal muscle is among the most plastic of tissues, remodelling to accommodate altered demands. Exercise induces a range of adaptations, notably a growth of capillaries (angiogenesis), while inactivity results in a loss of capillaries (rarefaction). As endurance activity relies on an adequate O2 supply to support oxidative phosphorylation, hypoxia within working muscle may act as an angiogenic stimulus, but additional candidates include chemical factors such as metabolic by-products (e.g. acidosis) or release of signalling molecules (e.g. VEGF, NO), and mechanical factors including response to muscle contractions (strain) or increased blood flow (hyperaemia). Optimising training interventions, for performance or rehabilitation, will benefit from better understanding of the local environment controlling the pattern of capillary distribution and its consequences for tissue oxygenation.