Metabolic cost and efficiency in two forms of squatting exercise in children and adults.

These experiments investigated the oxygen consumption and work efficiency of adults and children performing identical movement patterns. Adult men (mean age 24) and male children (mean age 12) performed squatting exercises with and without a pause at the lowest point of the squat. The former were termed no rebound squats and the latter were termed rebound squats. Subjects performed the exercises without load and with loads equal to 5%, 10% and 15% of body mass. The results showed that the children consumed 10% more oxygen per unit total body mass than the adults. The gross efficiency of the adults was significantly greater than that of the children. Net and apparent efficiencies were not significantly different between the age groups. Gross and net efficiencies declined with load. Rebound squats required 13% less oxygen than no rebound squats. The gross, net and apparent efficiency of rebound squats was significantly greater than that of no rebound squats. It is suggested that the greater gross efficiencies of adults is related to their lower basal metabolic rate and that the greater efficiency of rebound exercise is related to the storage of energy in elastic tissues.