A simplified approach for estimating the ventilatory and respiratory compensation thresholds

This study aimed to investigate whether ventilatory (VT) and respiratory compensation (RCT) thresholds could be derived from percentages of maximal running speed (Vmax). During the model building phase (1), VT & RCT of 31 competitive level athletes were identified with respiratory gas exchange. During the cross-validation phase (2), 20 subjects performed a treadmill test to identify Vmax and then they performed 30-min runs at velocities 2SE below or above the velocity at VT and RCT derived from (1), with measurement of blood lactate [BL], RPE, heart rate (HR), and speech comfort. Phase (1) revealed that VT and RCT were reached at 67 ± 9% and 84 ± 6% of Vmax. In (2) sustained running 2SE below VT (64% Vmax) was associated with the ability to finish 30-min, with low and constant [BL] (~2.5 mmol.l-1), moderate RPE (~3.0-3.5), a small HR drift, and ability to speak comfortably. Conversely, running at 2SE above RCT (86% Vmax) was associated with the inability to finish 30-min (18.5 ± 2.5 min to fatigue), increasing [BL] (end-exercise = 11.9 ± 0.9 mmol.l-1), high RPE (end-exercise = 8.9 ± 1.0), large HR drift (end-exercise = 98 ± 3% HRmax), and inability to speak comfortably. Simple percentages of Vmax (≤64% and ≥86%) obtained from a treadmill test without gas exchange, may be useful for prescribing exercise training intensities.