Association between Physical Activity and Adiposity in Adolescents with Down Syndrome

Obesity is highly prevalent among adolescents with Down syndrome (DS); however, reported associations between body composition and moderate-to-vigorous physical activity (MVPA) have been small and nonsignificant. The purpose of this study was to compare group differences between adolescents with and without DS, including dual-energy x-ray absorptiometry (DXA) measured body composition and accelerometer-measured physical activity, and then examine associations within adolescents with DS.

Thirty-nine adolescents (22 with DS and 17 typically developing controls) 12-18 yr of age participated in the study. Groups had similar distributions of age, sex, and Tanner pubertal stage. Body composition was assessed by DXA, body mass index (BMI), and BMI percentile. MVPA was measured with ActiGraph GT3X+ accelerometers.

Adolescents with DS had significantly higher BMI, BMI percentile, and DXA-derived percent body fat (%BF) as well as lower MVPA compared with controls (P < 0.05). Associations between MVPA and %BF in adolescents with DS were moderate (r = -0.39, P = 0.07) but substantially stronger than BMI (r = -0.19, P = 0.40). However, linear regression analyses identified Tanner stage (β = -0.77, P < 0.001) and MVPA (β = -0.34, P = 0.047) as significant predictors of %BF. No relevant associations between body composition and MVPA were observed in adolescents with typical development (P > 0.05).

Our findings suggest that MVPA is associated with adiposity when measured with DXA among adolescents with DS.