Phosphocreatine recovery overshoot after high intensity exercise in human skeletal muscle is associated with extensive muscle acidification and a significant decrease in phosphorylation potential

Abstract

The phosphocreatine (PCr) recovery overshoot in skeletal muscle is a transient increase of PCr concentration above the resting level after termination of exercise. In the present study [PCr], [ATP], [Pi] and pH were measured in calf muscle during rest, during plantar flexion exercise until exhaustion and recovery, using the 31P NMR spectroscopy. A significantly greater acidification of muscle cells and significantly lower phosphorylation potential (ΔG ATP) at the end of exercise was encountered in the group of subjects that evidenced the [PCr] overshoot as well as [ADP] and [Pi] undershoots than in the group that did not. We postulate that the role of the PCr overshoot-related transiently elevated [ATP]/[ADPfree] ratio is to activate different processes (including protein synthesis) that participate in repairing numerous damages of the muscle cells caused by intensive exercise-induced stressing factors, such as extensive muscle acidification, a significant decrease in ΔG ATP, an elevated level of reactive oxygen species or mechanical disturbances. © 2010 The Physiological Society of Japan and Springer.