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 (τVO(2)) 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 τVO(2). The VO(2) data from the first trial of three bouts were used to estimate τVO(2) for a single bout. Additionally, data collected from three bouts were ensemble-averaged to obtain τVO(2) for three averaged bouts as the criterion. RESULTS: There was a very high correlation between τVO(2) for a single bout (34.8±14.0 seconds) and τVO(2) for three averaged bouts (38.5±13.4 seconds) (r=0.926, p<0.001). However, τVO(2) for a single bout was smaller than that for three averaged bouts (p=0.006). CONCLUSION: τVO(2) for a single bout could reflect the relative difference in τVO(2) for three averaged bouts among individuals with stroke. However, it should be noted that τVO(2) for a single bout may be underestimated compared to τVO(2) for three averaged bouts.