The rate of PCr resynthesis is not a reliable index of skeletal muscle oxidative capacity

Abstract

phosphorylation in adults during the early post-exercise recovery period, they did not take into account the different end-of-exercise ph values in the two groups to properly infer on the skeletal muscle oxidative capacity on the basis of the τPCr. During recovery from exercise, phosphocreatine is resynthesized purely as a consequence of oxidative AtP synthesis and τPCr measurements have been used to characterize the mitochondrial function in a variety of conditions (roussel et al. 2000). however, several studies have clearly demonstrated that cytosolic ph has a strong influence (roussel et al. 2000). It is actually well acknowledged that τPCr is positively related to the extent of intracellular acidosis and PCr consumed (roussel et al. 2000). In other words, a significant intracellular acidosis and a large PCr consumption in exercising muscle would be associated with a slower PCr resynthesis (roussel et al. 2000). In the Kappenstein et al. study, cytosolic ph was reduced in a larger extent following high-intensity intermittent exercise in adults as compared to children so that muscle oxidative capacity could not simply be compared on the basis of τPCr measurements. Of note, several kinetic parameters are usually used to describe PCr changes during the exercise-to-recovery transition, including τPCr, the initial rate of PCr recovery (ViPCr) and the maximum aerobic capacity (Qmax) (tonson et al. 2010). these three parameters characterizing PCr resynthesis are correlated to oxidative capacity. however, in contrast to τPCr, ViPCr and Qmax are insensitive to exercise intensity and end-of-exercise metabolic conditions (roussel et al. 2000). On that basis, ViPCr and Qmax should be considered as additional indices to compare the post-exercise PCr recovery rate and mitochondrial oxidative capacity across different populations when end-ofexercise ph and PCr concentration values are different or Dear Editor,