Relationship between O2 consumption, high energy phosphates and the kinetics of the O2 debt in exercise.

Abstract

The oxygen consumption together with lactic acid production and concentration of ATP, ADP, and creatinephosphate was measured during exercise and recovery on an isolated dog gastrocnemius. Oxygen debt contraction and payment follow an exponential path with a half reaction time of about 20 sec. The concentration of ATP and ADP at steady state seem to be unaffected by the intensity of the exercise when this is submaximal and no appreciable production of lactic acid takes place. The concentration of creatinephosphate in muscle at steady state decreases with the intensity of the exercise. The ratio of the oxygen consumption at steady state to the alactic oxygen debt is identified with the speed constant of the resynthesis of phosphagen in muscle; the half reaction time of this process is 17–20 sec. The total alactic oxygen debt amounts to about 50 ml/kg of muscle. These figures are in good agreement with earlier data found in man.