Lactate Production and Anaerobic Work Capacity after Prolonged Exercise

Abstract
It has been found that previous heavy or long‐lasting exercise results in a diminished ability to raise the blood lactate concentration by exhaustive supermaximal work (Hedman 1957, Astrand et al. 1963, and others). No definitive explanation for this phenomenon has been given. It was the purpose of the present experiments to throw light on the question whether a diminishing store of carbohydrates in the body could be the cause for the declining ability to liberate energy anaerobically by breakdown of glycogen to lactic acid. In 3 subjects the stores of glycogen were presumed to be varied 1) by repeated bouts of supermaximal and submaximal exercise on the bicycle‐ergometer, and 2) by diet after previously depleting the carbohydrate stores by exercise. It was found that in all cases the ability to work anaerobically and to produce lactate decreased with decreasing amounts of available carbohydrate. Disturbances in water or electrolyte balance were avoided. It is tentatively suggested that the velocity of the enzymatic process glycogen—glucose‐1‐phosphate is the limiting factor, and that this process is slowed down by lactic acid accumulation, the more the lower the substrate (glycogen) concentration is. Glucose, which enters the glycogenolytic chain as glucose‐6‐phosphate, can partly restore the ability for lactate production.

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