Physical activity related energy expenditure and fat mass in young children.
OBJECTIVE
To examine whether body fat content in pre-pubertal children is influenced by physical activity related energy expenditure (AEE) and/or more qualitative aspects of physical activity.


METHODS
Cross-sectional study.


METHODS
101 pre-pubertal children were examined in Study 1: (age: 5.3 +/- 0.9 y; weight: 20.2 +/- 3.6 kg). In Study 2: 68 of the original children were re-examined (age: 6.3 +/- 0.9 y; weight: 23.6 +/- 5.0 y).


METHODS
Fat mass (FM) and fat free mass (FFM) were determined by bioelectrical resistance and skinfolds; AEE was estimated from the difference between total energy expenditure (TEE) by doubly labeled water and post-prandial resting energy expenditure (REE) by indirect calorimetry; qualitative information on activity was derived by questionnaire.


RESULTS
AEE was significantly correlated with FFM (r = 0.32 in both Studies) and body weight (r = 0.28 in Study 1; r = 0.29 in Study 2), but not FM. There were no significant relationships between AEE and any of the variables from the activity questionnaire in children (including TV time, playing time, and an accumulated activity index in h/week). After adjusting for FFM, age, and gender, FM was inversely related to activity time in h/week (partial r = -0.24 in Study 1; partial r = -0.32 in Study 2) but not AEE (P > 0.5).


CONCLUSIONS
After adjusting for FFM, age, and gender, a small portion of the variance in body fat mass in children (approximately 10%) is explained by time devoted to recreational activity, whereas none of the variance is explained by the combined daily energy expenditure related to physical activity.
Goran
M I
MI
Department of Nutrition Sciences, University of Alabama at Birmingham 35294, USA.
Hunter
G
G
Nagy
T R
TR
Johnson
R
R
D000273:Adipose Tissue; D001823:Body Composition; D002153:Calorimetry, Indirect; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005260:Female; D005502:Food; D006801:Humans; D008297:Male; D012146:Rest; D012885:Skinfold Thickness