Effects of active and passive recovery on blood lactate and blood pH after a repeated sprint protocol in children and adults.

ABSTRACT

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.