High-intensity training increases spontaneous physical activity in children: a randomized controlled study.

Abstract

To test the hypothesis that resistance training may increase spontaneous physical activity in children. Two junior ice hockey teams were randomly assigned to unchanged training schedules (team ZSC, 21 boys; mean age, 13.2 years) or to participate twice weekly in guided resistance training for 4 months (team GCK, 25 boys; mean age, 13.4 years). Spontaneous physical activity energy expenditure (SpAEE; 3-axial accelerometry for 7 days), muscle strength, and body composition (dual energy x-ray absorptiometry) were measured at 0, 4, and 12 months. Baseline measures did not differ in the groups, except for higher leg and trunk strength in team ZSC. In the intervention group compared with the control group, SpAEE significantly (P < or = .02) increased at 4 months (+25.5% versus 0%) and 12 months (+13.5% versus -9.5%). Leg and arm strength increased because of training intervention; all other variables were unchanged. None of these variables correlated with changes in SpAEE. In boys who play ice hockey, spontaneous physical activity is inducible with resistance training; this effect seems to be independent of changes in body composition and strength. If this was confirmed in unselected children, resistance training might be a new strategy for childhood obesity prevention programs.