ABSTRACT
Although it has been previously described that children display a greater resistance to fatigue as compared to adults during repeated bouts of high-intensity exercise (Ratel et al., 2002), the exact causative factors havenot been clearly discriminated. Several hypotheses related to metabolic changes during or between exercise bouts could be put forth. In that respect, the greater resistance to fatigue in children could be linked to a higher skeletal muscle oxidative capacity allowing a faster phosphocreatine (PCr) resynthesis and a faster restoration of short-term muscle power following each exercise bout (Bogdanis et al., 1996).Oxidative capacity can be estimated non-invasively from the rate of post-exercise PCr resynthesis using 31-phosphorus magnetic resonance spectroscopy (31P-MRS). However, using this method, conflicting results have been reported between children and adults (Kuno et al., 1995; Taylor et al., 1997) which could lead to misinterpretations. For instance, confounding factors such as end-of-exercise pH and PCr concentration have not been systematically taken into account (Roussel et al., 2000).
