Constant external work cycle exercise : the performance and metabolic effects of all-out and even-paced strategies

The purpose of the present study was to establish whether the performance of an all-out sprint could be replicated and the metabolic responses moderated in two further trials involving pre-set constant average pedalling rates. A total of 24 subjects (12 males and 12 females) completed a 30-s high-speed maximal all-out effort on a cycle ergometer against an applied resistance equal to 7.5% of their body mass. On two further occasions the applied resistance was increased so that the external work of the all-out effort could be replicated by adopting a pre-determined constant average pedal rate. When the required pedal rate was within the range of 60-90 rev.min-1 the subjects were able to maintain the rate for the full 30-s and so could replicate the external work of the all-out effort. They were unable to sustain a faster constant rate within the range of 97-150 rev.min-1 for the full 30 s, resulting in approximately 7% less external work being achieved (P < 0.05). A lower level of fatigue, reflected by less of a reduction in peak power output in a subsequent 6-s sprint (P < 0.05), arose as a result of similar work produced under constant paced conditions compared with the all-out effort. Also, post-exercise blood lactate, pH and ammonia were less disturbed (P < 0.05) following the paced trial compared with similar work produced in the all-out effort. A possible explanation for these findings is that there may be a partial sparing of some type II fibres as a consequence of an initial submaximal intensity of exercise during the paced trial.