Muscle phosphocreatine and pulmonary oxygen uptake kinetics in children at the onset and offset of moderate intensity exercise.

摘要

To further understand the mechanism(s) explaining the faster pulmonary oxygen uptake [Formula: see text] kinetics found in children compared to adults, this study examined whether the phase II [Formula: see text] kinetics in children are mechanistically linked to the dynamics of intramuscular PCr, which is known to play a principal role in controlling mitochondrial oxidative phosphorylation during metabolic transitions. On separate days, 18 children completed repeated bouts of moderate intensity constant work-rate exercise for determination of (1) PCr changes every 6 s during prone quadriceps exercise using (31)P-magnetic resonance spectroscopy, and (2) breath by breath changes in [Formula: see text] during upright cycle ergometry. Only subjects (n = 12) with 95% confidence intervals