Glycolytic and oxidative energy metabolism and contraction characteristics of intact human muscle.

It is proposed that glycolytic rate may be measured as lactate accumulation after electrical stimulation of the quadriceps femoris muscle under anaerobic conditions. The ratio of glucose 6-phosphate to lactate is an internal monitor of the glycolytic pathway. The phosphocreatine/lactate ratio links glycolysis and the creatine kinase reaction and could be used to distinguish abnormalities in energy metabolism. The rate of resynthesis of phosphocreatine after stimulation when the circulation is restored should be measure of oxidative phosphorylation. The relaxation rate seems to be a mechanical index of the metabolic state of the muscle.