The aim of this study was to evaluate the effect of a 15% increase in preferred pedal rate (PPR) on both time to exhaustion and pulmonary O(2) uptake (VO(2)) response during heavy exercise. Seven competitive cyclists underwent two constant-power tests (CPT) at a power output that theoretically requires 50% of the difference in VO(2) between the second ventilatory threshold and VO(2)max (Pdelta50). Each cyclist cycled a CPT at PPR (CPTPPR) and a CPT at +15% of PPR (CPT+15%) in a randomized order. The average PPR value was 94 +/- 4 rpm, and time to exhaustion was significantly longer in CPTPPR compared with CPT+15% (465 +/- 139 vs. 303+/- 42 s, respectively; p = 0.01). A significant decrease in VO(2) values in the first minutes of exercise and a significant increase in VO(2) slow component was reported in CPT+15% compared with CPT(PPR). These data indicate that the increase of 15% PPR was associated with a decrease in exercise tolerance and a specific VO(2) response, presumably due to an increase of negative muscular work, internal work, and an altering of motor unit recruitment patterns.