Total energy expenditure and spontaneous activity in relation to training in obese boys

Obese boys [n = 10, aged 10-11 y, average percent body fat (%BF) 32.4] were given a regimented training program (4 wk, 5 1-h sessions, 45 min cycling/wk at 50-60% of predetermined VO2max) to investigate whether they modify their energy expenditure by reducing or augmenting their spontaneous physical activities. No change was observed in mean weight (52.7 vs 52.9 kg), %BF based on 2H- and 18O-dilution and densitometry (32.4 vs 31.7), sleeping metabolic rate (5.83 vs 5.68 MJ/24 h), and spontaneous activity by heart rate recording (percent time of light intensity: 85.3 vs 83.6; medium: 11.2 vs 12.4; and heavy: 3.5 vs 3.9) and activity questionnaires (861 vs 821 min physical activity/wk). There was a 12% increase in average daily metabolic rate by doubly labeled water, half of which can be explained by the energy cost of training and the rest by an increase in energy expenditure outside the training hour. In conclusion, training leads to an appreciable augmentation in the overall energy expenditure of obese children, even with a lack of change in spontaneous physical activity.