Effects of Speech Passage Length on Accuracy of Predicting Metabolic Thresholds Using the Talk Test

The Talk Test (TT) is a simple technique for prescribing exercise training intensity, based on the ability to ‘speak comfortably’ after reciting a standard speech provoking stimulus. This study compares the length of the speech provoking stimulus on power output (PO) at standard TT speech comfort markers: last positive (LP), equivocal (EQ), negative (NEG), in relation to objective markers of exercise intensity, the ventilatory (VT) and respiratory compensation (RCT) thresholds. Eighteen healthy subjects performed incremental (25W/2 min) exercise with concomitant gas exchange to measure VT and RCT. They also performed (random order) incremental exercise without gas exchange while repeating standard speech provoking stimuli of 31, 62 and 93 words to allow identification of the LP, EQ and NEG stages of the TT. The mean (±SD) PO at LP (139±38, 117±39 and 103±38 W), EQ (164±38, 142±38 and 128±33 W) and NEG (196±42, 189±43, and 174±39 W) stages of the TT were analyzed for 31, 62 and 93 word passages, in relation to the PO at VT (128±43 W) and RCT (175±39W). PO at EQ and PO at NEG stages of the TT with the 93 word speech provoking stimulus were not significantly different than the PO at VT and PO at RCT, respectively. The mean error for predicting PO at VT approximated zero with the longer (93 word) speech passage duration for EQ (0.1±37 W) and for predicting the PO at RCT for NEG (0.1±29 W). The results suggest that a longer duration speech provoking passage optimizes accuracy of the TT estimation of VT and RCT.