Physiological drift during steady-state exercise based on the incremental Talk Test

Purpose. The Talk Test (TT) is recognised as a practical method for prescribing exercise intensity during incremental exercise, although its applicability to prolonged steady-state exercise – particularly with respect to physiological drift – remains underexplored. Therefore, this study aimed to evaluate whether workloads at different TT stages during incremental exercise predict responses during steady-state training. Methods. Well-trained individuals (1–3 h of hiking, 3–4 times per week) performed incremental exercise (2-min stages) to determine the equivocal (EQ), last positive (LP) and last positive-1 (LP-1) TT stages. Participants then completed 60-min uphill walking bouts at LP-1, LP and EQ intensities in random order. Repeated measures ANOVA with Tukey post-hoc tests assessed differences in physiological drift across TT stages during steady-state exercise. Results. During LP-1 and LP bouts, stable conditions were observed for the percentage of maximum heart rate (% HR_max) (< 85% HR_max), rating of perceived exertion (RPE) (< 4/10), blood lactate (2–3 mmol · l^–1) and TT score (~1.2/3). In contrast, during EQ, all values showed significant drift, including HR (> 95% HR_max), RPE (~7/10), blood lactate (~7 mmol · l^–1) and TT score (~2.4/3). Conclusions. Training intensity based on LP-1 or LP incremental TT provides conditions consistent with the moderate-intensity domain, with minimal drift during 60-min exercise. Steady-state exercise at the intensity of the EQ stage results in significant drift, comparable with the heavy or severe exercise domain (> maximal lactate steady-state). These findings suggest that TT-based intensities, particularly LP-1, may be suitable for prolonged training in physically active individuals, to build endurance. Future research should investigate the applicability of the TT in athletes, particularly its effectiveness for prolonged exercise.