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 ((Formula presented)VO₂) 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 (Formula presented)tVO₂. The VO₂ data from the first trial of three bouts were used to estimate TVO₂ for a single bout. Additionally, data collected from three bouts were ensemble-averaged to obtain (Formula presented)VO₂ for three averaged bouts as the criterion. Results There was a very high correlation between (Formula presented)VO₂ for a single bout (34.8±14.0 seconds) and TVO₂ for three averaged bouts (38.5±13.4 seconds) (r=0.926, p<0.001). However, (Formula presented)VO₂ for a single bout was smaller than that for three averaged bouts (p=0.006). Conclusion (Formula presented)VO₂ for a single bout could reflect the relative difference in (Formula presented)VO₂ for three averaged bouts among individuals with stroke. However, it should be noted that (Formula presented)VO₂ for a single bout may be underestimated compared to (Formula presented)VO₂ for three averaged bouts.