Changes in Body Composition and Physical Fitness in Adolescents with Down Syndrome: The UP&DOWN Longitudinal Study

Background: Adolescents with Down syndrome (DS) demonstrate higher values of body composition and lower levels of physical fitness when compared with their peers with typically developing (TD) or their peers with intellectual disability but without DS. Objective: To examine, during a 2-year period, changes in indicators of body composition and physical fitness components in TD adolescents and adolescents with DS. Methods: Hundred adolescents with DS (64 males) aged 11-20 years old were matched by sex to 163 TD adolescents (108 males) aged 12-18. Indicators of body composition were determined by body mass index (BMI), waist circumference, waist-to-height ratio, skinfolds, and percentage of body fat (%BF). Components of physical fitness were assessed by the Assessing Level of Physical Activity (ALPHA) health-related fitness test battery for youth. Results: In the 2-year follow-up, significant (p < 0.05) decreases in BMI and increases in cardiorespiratory fitness and handgrip strength were seen for both groups; decreases in %BF were only seen for participants with DS; and increases in standing long jump were seen only for TD adolescents. Conclusions: Results indicate that during the 2-year study period, there were significant decreases in BMI and significant increases in handgrip strength and cardiorespiratory fitness in the TD group. For participants with DS, there was a significant decrease in %BF. However, participants with DS did not exhibit improvements in physical fitness.