Response to Exercise Generates Lactate and Fluid Intake: Effects on Mitochondrial Function in Heart and Vascular Smooth Muscle

potential mechanisms that could account for the beneficial effects of exercise on cardiovascular structure and function. Exercise-induced effects on mitochondrial function and fluid loss/replacement have been proposed as intermediary processes. The protective effects of mitochondrial function against dia-betes mellitus and cardiovascular aging are well documented. Thornton and Hess1 propose that exercise exerts a positive effect on mitochondrial function through the enhanced supply of substrates and lactate in particular. This mechanism is plausible. Indeed, the role of lactate has evolved from simply being a “waste ” product of anaerobic metabolism into an important substrate for mitochondrial function and a gluconeogenic precur-sor via the lactate shuttle mechanism.2 Thornton and Hess1 further speculate that exercise may facilitate the lactate transport into the mitochondria through the increased expression of mono