Critical power testing or self-selected cycling: Which one is the best predictor of maximal metabolic steady-state?

Critical power (CP) demarcates the boundary between heavy and very heavy exercise intensity domains, and therefore, the power output (PO) that can be sustained at the maximal metabolic steady-state during constant-PO exercise (i.e., maximal lactate steady-state (MLSS)). However, the estimated CP does not always reflect a sustainable intensity of exercise, where blood lactate concentration ([La]) and oxygen uptake (VO2) reach a plateau. Objectives: To test cyclists' ability to predict their highest PO associated with metabolic steady-state based on their own perception of effort. Design: Repeated measures. Methods: Thirteen healthy young cyclists (26 +/- 3years; 69.0 +/- 9.2 kg; 174 +/- 10 cm) were tested. Five time to -exhaustion trials were used to derive CP based on a 2-parameter hyperbolic model (CPHYP). Participants performed two 30-min rides at a self-selected PO that they considered their highest sustainable exercise intensity (CPsELF). Additionally, MLSS was determined as the highest PO at which variation in [La] <= 1.0 mmol L-1 between the 10th and 30th min was observed during a 30-min ride. Results: Mean PO at CPsELF (233 +/- 42 W) was similar (p > 0.05) to MLSS (233 +/- 41 W), whereas CPHYP (253 +/- 44 W) consistently overestimated (p < 0.05) the PO associated to metabolic steady-state. The limits of agreement (LOA) between MLSS and CPSELF were -20 to +20W (bias = OW, p> 0.05), whereas the LOA between CPHYP and CPSELF were 40 to OW (bias = -20 W, p < 0.05). CPSELF and MLSS presented similar (p> 0.05) metabolic response (i.e., VO2, [La], and HR). Conclusions: Compared to CPHYP, CPSELF may offer a more precise approach to predict the constant -PO associated with maximal physiological steady-state. (C) 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.