Physical fitness predicts functional tasks in individuals with Down syndrome

Individuals with Down syndrome (DS) exhibit reduced strength and aerobic capacity, which may limit their ability to perform functional tasks of daily living. This study was conducted to examine the relationship between timed performance on functional tasks of daily living and age, knee isometric strength, and peak aerobic capacity in a group of individuals with DS. This was a cross-sectional study involving 35 individuals (27 +/- 7.5 yr) with DS. Participants completed an isometric test of knee extensor and flexor strength, an individualized exercise test to measure peak aerobic capacity, and three timed functional tasks of daily living, which included chair rise, gait speed, and stair ascent and descent. Multiple regression analyses were performed to examine the relationship between timed task performance and age, knee isometric strength, and peak aerobic capacity. The multiple regression models explained 11-29% of the variance in timed task performance. Knee extensor strength was the most influential variable in predicting timed task performance (squared semipartial correlation coefficient [sr2] = 0.11-0.20), followed by aerobic capacity (sr2 = 0.10-0.14). Age was not a significant predictor of timed task performance. These findings suggest that physical fitness (defined here as aerobic capacity and knee extensor strength) limits the ability of adults with DS to perform functional tasks of daily living. Randomized controlled trials should be performed to test the probable causal relationship between exercises designed to improve physical fitness and functional tasks of daily living.