Intensity effect of active recovery from glycolytic exercise on decreasing blood lactate concentration in prepubertal children

Purpose: Children's performance after intense exercise is known to recover faster than that of adults. However, very little is known about the physiological processes that differentiate children from adults in their recovery. The purpose of this study was to compare, in children, the decrease in blood lactate concentration ([La]) during various intensities of active recovery from highly intense exercise with that during passive recovery. Methods: Subjects were 15 healthy, physically active, prepubertal, 9- to 11-yr-old boys (N = 8) and girls (N = 7). Subjects performed three 40-s cycling bouts at 150% peak oxygen consumption ((V) over dotO(2peak)), with two 50-s rest intervals, followed by 2 min of passive recovery and 23 min of one of four randomly-assigned recovery levels: passive and 40%, 50%, and 60% (V) over dotO(2peak) (RP, R40, R50, and R60, respectively). Results: Mean values of peak [La] (by treatment) ranged between 9.9 +/- 1.5 and 10.8 +/- 2.0. Whereas HR and (V) over dotO(2) remained relatively higher, [La] decreased faster during all active recoveries compared with the passive mode. [La] during R60 was higher compared with [La] during R40. [La] was slightly higher in the first 10 min of R40 compared with R50, whereas from the 5th min onward, this difference was reversed. A similar pattern was seen in the boys and girls, separately. The calculated half-life of [La] was significantly higher during the passive compared with all three active recoveries, with no differences among the latter (22.0 +/- 5.0, 10.3 +/- 1.9, 10.5 +/- 2.2, and 11.5 +/- 2.1 min during RP, R40, R50, and R60, respectively). Conclusions: In summary, similar to the case in adults, the decrease in [La] after intense exercise in children is faster during active recovery compared with the passive mode. Further research is required to determine whether performance recovery parallels that of [La] in children and adults of both genders.