From our results we suggest relatively higher rates of oxidative ATP formation in children's muscle for covering the ATP demand of high-intensity intermittent exercise compared to adults, enabling children to begin each exercise interval with significantly higher PCr concentrations and leading to an overall lower muscle acidification.

The aim of this study was to compare the effect of active (AR) and passive recovery (PR) after a high-intensive repeated sprint running protocol on physiological parameters in children and adults. Blood lactate (La) and blood pH were obtained during two sets of 5 × 5 s all-out sprints and several times during subsequent 30-min recovery in 16 children and 16 adults. End-exercise La was significantly lower and pH significantly higher in children (La: 5.21 ± 2.73 mmol·L-1; pH: 7.37 ± 0.06) compared with adults (La: 10.35 ± 5.76 mmol·L-1; pH: 7.27 ± 0.10) (p < .01). La half-life during postexercise recovery was significantly shorter in children (AR: 436 ± 371 s, PR: 830 ± 349 s) than in adults (AR: 733 ± 371 s, PR: 1361 ± 372 s), as well as in active compared with passive recovery for both age groups (p < .01). The age x recovery interaction for La half-life only approached statistical significance (p = .06). The results suggest a faster lactate disappearance and an earlier return to resting pH after a repeated sprint running protocol in children compared with adults and a less pronounced advantage of active recovery in children.

No abstract

No abstract