A Single Bout of Constant-Load Exercise Test for Estimating the Time Constant of Oxygen Uptake Kinetics in Individuals With Stroke.

OBJECTIVE To examine the relationship between the time constant of oxygen uptake kinetics during the onset of exercise (τVO2) estimated from a single exercise bout and that obtained from three averaged exercise bouts in individuals with stroke. METHODS Twenty participants with stroke performed three bouts of a constant-load pedaling exercise at approximately 80% of the workload corresponding to the ventilatory threshold to estimate τVO2. The VO2 data from the first trial of three bouts were used to estimate τVO2 for a single bout. Additionally, data collected from three bouts were ensemble-averaged to obtain τVO2 for three averaged bouts as the criterion. RESULTS There was a very high correlation between τVO2 for a single bout (34.8±14.0 seconds) and τVO2 for three averaged bouts (38.5±13.4 seconds) (r=0.926, p<0.001). However, τVO2 for a single bout was smaller than that for three averaged bouts (p=0.006). CONCLUSION τVO2 for a single bout could reflect the relative difference in τVO2 for three averaged bouts among individuals with stroke. However, it should be noted that τVO2 for a single bout may be underestimated compared to τVO2 for three averaged bouts.