Road cycle TT performance: Relationship to the power-duration model and association with FTP

Purpose: To determine the accuracy of critical power (CP) and Wʹ (the curvature constant of the power-duration relationship) derived from self-paced time-trial (TT) prediction trials using mobile power meters to predict 16.1 km road cycling TT performance. This study also aimed to test the agreement between functional threshold power (FTP) and CP. Methods: Twelve competitive male cyclists completed an incremental test to exhaustion, a 16.1-km road TT, an FTP test, and 4–5 self-paced TT bouts on a stationary bike within the lab, using mobile power meters. Results: CP and Wʹ derived from the power-duration relationship closely predicted TT performance. The 16.1 km road TT completion time (26.7 ± 2.2 min) was significantly correlated with the predicted time-to-completion (27.5 ± 3.3 min, r= 0.89, P<0.01). CP and FTP were not significantly different (275 ± 40 W vs. 278 ± 42 W, P>0.05); however, the limits of agreement between CP and FTP were 30 to -36 W. Discussion: The findings of this study indicate that CP and Wʹ determined using mobile power meters during maximal, self-paced TT prediction trials can be used to accurately predict 16.1-km cycling performance, supporting the application of the CP and Wʹ for performance prediction. However, whilst we demonstrated that the FTP was not significantly different from CP, the limits of agreement were too large to consider FTP and CP interchangeable.