Reproducibility of metabolic anchor points using gas exchange and the talk test

Abstract

The Talk Test (TT) has generated interest as a simple method for estimating ventilatory (VT) and respiratory compensation (RCT) thresholds. Comparison studies suggest that the TT is quite accurate at measuring VT and RCT across a variety of populations. However, no data are available on the reproducibility of responses obtained with the TT. Purpose: This study was designed to measure the comparative ability of respiratory gas exchange (GE) and the TT to identify the VT, RCT and maximal power output (PO) during cycle ergometry. Methods: Healthy volunteers (N = 24) performed 4 incremental (25W + 25W/2 min) exercise tests, in a counterbalanced order. In 2 of the tests, GE was used to define PO at VT, RCT, and max effort. In the other 2 trials, the TT was repeated during the last 30s of each 2 min stage, and was used to define PO at VT (equivocal TT), RCT (negative TT), and maximal effort. Results: There were significant differences between GE and TT for estimating VT (GE: 124W vs. 122W; TT: 154W vs. 153W (p=.001)) and RCT (GE: 190W vs. 186W; TT: 204W vs. 204W (p=.002)). There were no significant differences between GE and TT for estimating Maximal PO (GE: 238W vs. 237W; TT: 243W vs. 241W (p=.134)). There were no significant differences within method for estimating VT (GE: 124W vs. 122W (p=.780); TT: 154W vs. 153W (p=.788)), RCT (GE: 190W vs. 186W (p=.455); TT: 204W vs. 204W (p=.851)), and Maximal PO (GE: 238W vs. 237W (p=723); TT: 243W vs 241W (p=.621)). Conclusions: Estimates of PO, VT and RCT using the TT appear to be reproducible within method, and appear to be more reproducible than similar results measured by GE whether GE was measured by Watts or VO2. The TT EQ overestimates GE VT. Similarly, previous findings of a close correspondence between TT EQ and VT was not reproduced, particularly at low PO (<100 Watts).