Physiology of Marathon Running

Like most endurance athletes, marathon runners are characterized by their highly developed aerobic capacities (V̇o₂max) and an ability to tolerate high rates of energy expenditure (70% to 90% V̇o₂max) without accumulating blood lactate. During marathon competition these men must alter their speed to compensate for the detrimental effects of uneven terrain, wind resistance, and thermal stress. Such factors add to the circulatory and metabolic demands of running. Heat produced in the active muscles must be transported to the body surface via the circulatory system and subsequently dissipated to the environment. Since the major responsibility of circulation is to transport nutrients and metabolic wastes, increasing the environmental heat stress will overload the circulatory system, thereby reducing performance and posing a risk to the runners' health.