The influence of physical activity on body weight in children and adolescents is controversial.
In this study, a team of researchers from Europe tested whether intensity and duration of physical activity differed between obese and normal-weight adolescents, with no difference in estimated energy expenditure.
They compared physical activity in 18 (8 male, 10 female) obese adolescents (14 to19 years) with that in a matched, normal-weight control group.
Obese adolescents had a body mass index (BMI) (in kg/m2) greater than 30, whereas the control group had a BMI less than 27.
The team measured total energy expenditure (TEE) using the doubly labeled water method.
|Physical activity level was significantly lower in the obese group.|
|American Journal of Clinical Nutrition|
Physical activity was measured simultaneously by accelerometry.
The team then determined the physical activity level as the ratio of TEE to the resting metabolic rate (RMR) and activity energy expenditure as 0.9 TEE minus RMR.
Accelerometry data included total physical activity (counts × min-1 × d-1), accumulated and continuous duration of activity, and continuous 10-minute periods of physical activity of moderate intensity.
The research team found no significant difference in adjusted (analysis of covariance) TEE, RMR, or the activity-related energy expenditure between groups.
However, the physical activity level was significantly lower in the obese group.
Differences in total physical activity, accumulated time, continuous time, and continuous 10-min periods of physical activity of moderate intensity were observed between groups.
Dr Ulf Ekelund's team concluded, "Obese adolescents are less physically active than are normal-weight adolescents, but physical activity-related energy expenditure is not significantly different between groups".
"The data suggest that physical activity is not necessarily equivalent to the energy costs of activity".