Underestimation of economy from incremental tests: Implications for practitioners

Abstract

Summary Purpose Current practices for estimating exercise economy using an extrapolation of sub-gas exchange threshold (GET), and to a lesser degree supra-GET, data will likely result an underestimation of actual economy, however, this is yet to be empirically demonstrated. Despite contentions, these protocols remain in widespread use. Therefore, the aim of the present study was to investigate whether estimation of exercise economy from moderate only, and moderate and heavy intensity exercise underestimates actual oxygen cost. Summary of Facts and Results Twelve recreationally active males (mean ± SD; age 29 ± 9y, height 1.81 ± 0.07 m, mass 81.4 ± 10 kg) volunteered for this study. Following a maximal ramp test to determine the VO2peak, peak power (Wpeak), VO2 and power output at GET, participants completed a sub-GET only, a sub/supra-GET (both five-stage incremental tests), and a fixed WR protocol (10 min duration at 75% Δ). Economy was determined by extrapolation of sub- and sub/supra-GET VO2 and directly measured VO2 at 75% Δ. Within-subjects ANOVA was performed to identify differences in economy between sub-GET only, sub/supra-GET, and fixed WR protocols. Significant effects between the predicted values compared to the measured value were investigated post hoc using Bonferroni corrected paired t-tests. There was a significant effect of protocol on VO2 and economy (P Conclusion The large error obtained by extrapolating sub-GET exercise intensities for the purpose of estimating exercise economy needs to be acknowledged, as does the concomitant, albeit reduced, error that remains when incorporating supra-GET data. Exercise scientists and practitioners should adopt more appropriate testing protocols such as serial assessments, up-to and including race pace, to accurately assess economy.