Daily energy expenditure of young boys as related to maximal aerobic power.

Daily energy expenditure, and participation in regular physical activity over one year, were determined in 28 boys (age 12.3 years) by (1) heart rate (fh) recorded on an oxford Medilog tape recorder and used to approximate energy expenditure using individual fh-VO2 relationships established from a standard step test; total daily average energy expenditure, time spent, and energy expended in activity above a defined threshold, training fh = (.6 (fh max - fh rest) + fh rest) and, (2) a questionnaire designed to determine involvement in regular physical activities over the preceeding year. Maximal oxygen uptake (2.47 +/- 0.36 l-min-1) was measured on a treadmill test. A step-wise multiple regression analysis was used to describe the association between maximal aerobic power and the measures of body size (wt. - 43.8 kg, ht. - 152.2 cm), fatness (sum of skinfolds -67.4 mm), daily energy expenditure (11.66 MJ), and participation in regular physical activity. Body mass and fatness made the only significant contributions to the variance (R2 = 0.77). The relationship was VO2 (l.min-1) = 0.47 (body mass- kg) -0.04 (sum of 6 skinfolds) + 0.71. Measures of daily energy expenditure, the time the heart rate was above a training threshold, and the number of regular physical activities, added little to the measured variance (R2 = 0.78) above that accounted for by body mass amd fatness.