Including supramaximal verification reduced uncertainty in VO2peak response rate

Abstract

Many reports describe using a supramaximal verification phase—exercising at a power output higher than the highest power output recorded during an incremental cardiopulmonary test—to validate VO2max. The impact of verification phases on estimating the proportion of individuals who increased VO2peak in response to high-intensity interval training (HIIT) remains an underexplored area in the individual response literature. This analysis investigated the influence of same-day and separate-day verification phases during repeated measurements (incremental tests—INCR1 and INCR2; incremental tests + supramaximal verification phases—INCR1+ and INCR2+) of VO2peak on typical error (TE) and the proportion of individuals classified as responders (i.e., the response rate) following 4 weeks of HIIT ( n = 25) or a no-exercise control period ( n = 9). Incorporation of supramaximal verification consistently reduced the standard deviation of individual response, TE, and confidence interval (CI) widths. However, variances were statistically similar across all groups ( p > 0.05). Response rates increased when incorporating either one (INCR1 to INCR1+; 24%–48%, p = 0.07) or two (INCR2 to INCR2+; 28%–48%, p = 0.063) supramaximal verification phases. However, response rates remained unchanged when either zero-based thresholds or smallest worthwhile difference response thresholds were used (50% and 90% CIs, all p > 0.05). Supramaximal verification phases reduced random variability in VO2peak response to HIIT. Compared with separate-day testing (INCR2 and INCR2+), the incorporation of a same-day verification (INCR1+) reduced CI widths the most. Researchers should consider using a same-day verification phase to reduce uncertainty and better estimate VO2peak response rate to HIIT.