Background

Aerobic capacity is an important and independent predictor of cardiovascular disease risk and mortality and is negatively associated with body fat percentage and fat mass.Individuals with Down syndrome (DS) have very low aerobic capacity and high body mass index, but interestingly, these constructs are not associated in this population.Accurate measures of body composition have not been previously available in this population to determine if this relationship holds true. PURPOSE: To determine the associations between accurate measures of body composition and aerobic capacity in individuals with DS compared to an age-matched control group.

Methods

Persons with (n=11; 25±4 yr; 4 males) and without DS (CON) (n=9; 24±4 yr; 4 males), matched for age and sex, had body composition assessed by dual energy x-ray absorptiometry and aerobic capacity measured with indirect calorimetry during a graded exercise test on a treadmill.

Results

Individuals with DS, when compared to CON, had a greater BMI (30.9±5.4 vs. 23.7±4.1 kg/m2) and waist circumference (93.2±9.5 vs. 81.9±0.1 cm), but lower aerobic capacity (22.1±5.2 vs. 33.3±8.0 mL/kg/min) (p<0.05).Body fat % (35.2±11 vs. 33.7±8%), fat mass (8.8±3.5 vs. 7.6±2.1 kg), and lean mass (47.9±8 vs. 44.4±12.1 kg) were not different between groups.Body fat % (r= -0.78) and lean mass (r= 0.74) were only correlated to aerobic capacity within the CON (p<0.05), and BMI was not related to aerobic capacity in either group.

Conclusions

These data suggest that aerobic capacity is not influenced by lean and fat mass among individuals with DS.It appears that having DS plays a larger role on aerobic capacity than body composition, which contrasts the expected relationship seen among peers without DS.