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 (V˙O2 ) 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±9.2kg; 174±10cm) 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] ≤1.0mmolL-1 between the 10th and 30th min was observed during a 30-min ride.

RESULTS: Mean PO at CPSELF (233±42W) was similar (p>0.05) to MLSS (233±41W), whereas CPHYP (253±44W) 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=0W, p>0.05), whereas the LOA between CPHYP and CPSELF were -40 to 0W (bias=-20W, p<0.05). CPSELF and MLSS presented similar (p>0.05) metabolic response (i.e., V˙O2 , [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.