Ability of mechanical power estimations to explain differences in metabolic cost of walking and running among children

The relationship between metabolic cost and three estimates of mechanical power was examined for three groups of children. Thirty children, aged 7–8 (n = 10), 10–12 (n = 10) and 15–16 (n = 10) years, performed 4-min bouts of submaximal treadmill exercise at 6 randomly assigned speeds, 2 walking and 4 running. When metabolic and mechanical power measures were correlated, the two segmental methods were good predictors of O2 for individuals, but not for groups. When two age groups performed the same absolute speed, O2 was significantly different between groups, but mechanical power and energy transfer rates were not. The lower metabolic cost of the older children could not be explained by differences in mechanical power or energy transfer rates