Relationship between physical inactivity and adiposity in prepubertal boys.
OBJECTIVE
To study the relationship between the energy expenditure for activity (EEAct), the level of activity and adiposity in a group of 9-year-old boys (n = 28) with different body composition (body weight, 38 +/- 10 kg [range, 23 to 66 kg]; fat mass, 23% +/- 10% [range, 8% to 42%]).


METHODS
Total energy expenditure (TEE) was measured by means of the heart-rate monitoring method. EEAct was calculated as TEE-(REE+0.1 TEE), where REE is the postabsorptive resting energy expenditure and 0.1 TEE corresponds to the postprandial thermogenesis (approximately 10% of TEE).


RESULTS
TEE, REE, and EEAct were 9388 +/- 1859, 5154 +/- 642, and 3295 +/- 1356 l J/day, respectively. Daily time devoted to sedentary and nonsedentary activities averaged 290 +/- 155 minutes (range, 69 to 621) and 534 +/- 150 minutes (range, 180 to 783), respectively. Time spent on sedentary activities was directly proportional to fat mass percentage (r = 0.46; p < 0.05). It was the only variable, among the free-living physical-activity [EEAct, TEE/(REE+0.1 TEE) ratio, time spent in nonsedentary and sedentary activities] variables, which remained significantly in the multiple step-down regression analysis final equation (r = 0.46; p < 0.05).


CONCLUSIONS
The positive relationship between adiposity and time spent on sedentary activities in 9-year-old boys suggests the importance of the role played by muscular activity, at least in the maintenance of obesity in childhood. Prepubertal children should be encouraged to spend less time on sedentary activities to treat and prevent their obesity.
Maffeis
C
C
Department of Pediatrics, University of Verona, Polyclinic, Italy.
Zaffanello
M
M
Schutz
Y
Y
D000273:Adipose Tissue / Q000033:anatomy & histology*; D001823:Body Composition; D001827:Body Height; D015992:Body Mass Index; D001833:Body Temperature Regulation; D001835:Body Weight; D002245:Carbon Dioxide / Q000378:metabolism; D002648:Child; D004063:Digestion; D004435:Eating; D004734:Energy Metabolism / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory; D009043:Motor Activity; D018482:Muscle, Skeletal / Q000502:physiology; D009765:Obesity / Q000503:physiopathology / Q000517:prevention & control / Q000628:therapy; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology; D011627:Puberty; D011659:Pulmonary Gas Exchange; D012044:Regression Analysis; D012146:Rest / Q000502:physiology; D012885:Skinfold Thickness; D013997:Time Factors
D002245:Carbon Dioxide