Effect of pedal cadence on parameters of the hyperbolic power-time relationship.

The purpose of this study was to evaluate the effect of pedal cadence methodology on the relationship between power output and time to exhaustion. Twenty-four subjects each performed 12 all-out cycle ergometer tests (four at a constant 60 rpm, four at a constant 100 rpm, and four where they were allowed to select and, within each test, vary their cadence). The parameters of the hyperbolic power-time relationship, AWC (anaerobic work capacity) and CP (critical power), were estimated for each pedal cadence methodology using three regression models: nonlinear power-time, linear work-time, and linear power-time-1. In all cases, R2 was high and standard errors of the estimate of AWC and CP were low. With the two constant rpm methodologies, the estimates of AWC and CP were influenced by the choice of regression model. The estimates of AWC and CP were also influenced by the pedal cadence in the all-out tests. For example, the CP derived from the 100 rpm tests (mean +/- SD: 195 +/- 50 W) was lower (p < 0.05) than the CP from the other methodologies (207 +/- 50 W and 204 +/- 48 W), and the AWC from the variable cadence methodology (16.1 +/- 6.2 kJ) was greater than the AWC from constant rpm trials (14.5 +/- 5.9 kJ and 14.6 +/- 5.7 kJ). It is concluded that pedal cadence methodology influences the parameters of the power-time relationship.