Purpose: The aim of this study was to examine whether adiposity level is associated with subsequent physical activity (PA) level in childhood.
Methods: Study participants were 326 children participating in the Iowa Bone Development Study. PA and fat mass were measured using accelerometers and dual-energy x-ray absorptiometry (DXA) at approximately 5, 8, and 11 yr. Data for relevant variables such as parents' education and PA levels and family income were also collected. Gender-specific generalized linear models were fit to examine the association between percentage body fat (%BF) at age 8 and intensity-weighted moderate- to vigorous-intensity PA (IW-MVPA) at age 11.
Results: After adjusting for IW-MVPA at age 8, the interval between the age 8 and 11 examinations, residualized change scores of %BF and IW-MVPA from age 5 to 8, and mother's education level, %BF at age 8 was negatively associated with IW-MVPA at age 11 among boys (P < 0.05). After adjusting for IW-MVPA at age 8, physical maturity, and family income, %BF at age 8 was negatively associated with IW-MVPA at age 11 among girls (P < 0.05). Categorical data analysis also showed that the odds ratio (OR) of being in the lowest quartile relative to the highest quartile of IW-MVPA at age 11 for boys and girls with high %BF at age 8 were approximately four times higher than the OR for those with low %BF at age 8 (OR = 4.38, 95% CI = 1.05-18.24 for boys; OR = 4.48, 95% CI = 1.35-14.85 for girls).
Conclusions: This study suggests that adiposity level may be a determinant of PA behavior. Specific intervention strategies for overweight children may be needed to promote PA.
1Department of Health Studies, University of Chicago, Chicago, IL; 2Department of Health and Human Physiology, University of Iowa, Iowa City, IA; 3Department of Epidemiology, University of Iowa, Iowa City, IA; 4Department of Pediatrics, University of Iowa, Iowa City, IA; and 5Department of Preventive and Community Dentistry, University of Iowa, Iowa City, IA
Address for correspondence: Kathleen F. Janz, Ed.D., FACSM, 130 FH, Department of Health and Human Physiology, University of Iowa, Iowa City, IA 52242; E-mail: firstname.lastname@example.org.
Submitted for publication April 2010.
Accepted for publication June 2010.