Oxygen uptake kinetics during exercise in adults with Down syndrome

Persons with Down syndrome (DS) have diminished submaximal and peak work capacity. This study evaluated the dynamic response of oxygen uptake at onset and recovery (VO2 kinetics) of constant-load exercise (moderate intensity 45% VO2peak) in adults with DS. A total of 27 healthy participants aged 18–50 years performed graded treadmill exercise to assess peak VO2: 14 with DS (9 males and 5 females) and 13 controls without disabilities (9 males and 4 females). Subjects also performed constant-load exercise tests at 45% VO2peak to determine VO2 on-transient and VO2 off-transient responses. Peak VO2 was lower in participants with DS as compared to controls (DS 30.2 ± 7.1; controls 46.1 ± 9.6 mL kg−1 min−1, P < 0.05). In contrast, at 45% VO2peak, the time constants for the VO2 on-transients (DS 34.6 ± 9.1; controls 37.6 ± 9.0 s) and VO2 off-transients (DS 36.5 ± 12.3; controls 37.7 ± 7.0 s) were not significantly different between the groups. Additionally, there were no differences between on-transient and off-transient time constants in participants with DS or controls. These data demonstrate that the VO2 kinetics at onset and recovery of moderate intensity exercise is similar between adults with DS and controls. Therefore, the submaximal exercise performance of these individuals is not affected by slowed VO2 kinetics.