Purpose: This study examined the effects of age on recovery of peak torque of knee extensors (PTEX) and flexors (PTFL), and total work (TW) during high-intensity intermittent 30-s (HI30) and 60-s (HI60) exercise in boys (N=19; age, 11.4+/-0.5 yr), teens (N=17; age, 14.7+/-0.4 yr), and men (N=18; age, 24.1+/-2.0 yr).
Methods: Each age group's subjects were subdivided to participate in an HI30 or an HI60 protocol. The HI30 involved 4x18 maximal knee extensions and flexions (1-min rest between sets), and the HI60 comprised of 2x34 reps (2-min rest). PTEX (N.m.kg), PTFL (N.m.kg), and TW (J.kg) were recorded at each set. The percent recovery of PTEX, PTFL, and TW was calculated as percent of the value achieved in the first set.
Results: In HI60, the percent recovery for PTEX, PTFL, and TW after the first set was higher in boys compared with teens and men (P<0.01). In HI30, the percent recovery for PTEX, PTFL, and TW was higher in boys compared with men in all sets (P<0.01), and in teens compared with men in the last two sets (P<0.05). The percent recovery of PTFL and TW was higher in boys compared with teens in the last two sets (P<0.05). Lactate increase was most pronounced in men, less pronounced in teens, and least pronounced in boys (P<0.01). Heart rate recovered faster in boys compared with teens and men in both protocols (P<0.05).
Conclusions: The recovery was faster in boys than in teens and men during HI30 and HI60, as evident by the greater percent recovery in boys for a given time. Furthermore, it appears that the rate of recovery during HI30 and HI60 anaerobic exercise is maturity dependent.