Power–cadence relationship in endurance cycling

In maximal sprint cycling, the power–cadence relationship to assess the maximal power output (Pmax) and the corresponding optimal cadence (Copt) has been widely investigated in experimental studies. These studies have generally reported a quadratic power–cadence relationship passing through the origin. The aim of the present study was to evaluate an equivalent method to assess Pmax and Copt for endurance cycling. The two main hypotheses were: (1) in the range of cadences normally used by cyclists, the power–cadence relationship can be well fitted with a quadratic regression constrained to pass through the origin; (2) Pmax and Copt can be well estimated using this quadratic fit. We tested our hypothesis using a theoretical and an experimental approach. The power–cadence relationship simulated with the theoretical model was well fitted with a quadratic regression and the bias of the estimated Pmax and Copt was negligible (1.0 W and 0.6 rpm). In the experimental part, eight cyclists performed an incremental cycling test at 70, 80, 90, 100, and 110 rpm to yield power–cadence relationships at fixed blood lactate concentrations of 3, 3.5, and 4 mmol L−1. The determined power outputs were well fitted with quadratic regressions (R2 = 0.94–0.96, residual standard deviation = 1.7%). The 95% confidence interval for assessing individual Pmax and Copt was ±4.4 W and ±2.9 rpm. These theoretical and experimental results suggest that Pmax, Copt, and the power–cadence relationship around Copt could be well estimated with the proposed method.