Day to day variation in time trial cycling performance.

In an attempt to assess the reproducibility of laboratory cycling performance, eight well-trained (VO2max = 4.6 +/- 0.2 l.min-1) male cyclists completed 12 trials involving 4 successive performance rides at each of three total work outputs (approximately 1600, 200, and 14 kilojoules, respectively). These trials, designated as long, medium, and short trials (LT, MT, ST), represented exercise bouts of 105.12 +/- 0.41, 12.03 +/- 0.17 and 0.55 +/- 0.11 minutes, respectively. The trials, conducted on a computerized cycle ergometer in an isokinetic mode, were separated by a minimum of 72 hrs. All trials for each subject were completed at the same time of day. In all trials, subjects were allowed to select the pace in order to complete the ride in the shortest possible time. The mean coefficient of variation (CV) for performance time in each trial was: LT = +/- 1.01%, MT = +/- 0.95%, and ST = +/- 2.43%, respectively. The CV for performance time in ST was significantly greater than the CV in either LT or MT. In LT, performance time was significantly faster, and the mean % VO2max was significantly higher in trial 4 versus trials 1-3. There was no order effect in the MT or ST rides. The CV for mean VO2 (l.min-1), mean % VO2max, and RER during the LT rides were +/- 3.02%, +/- 3.64%, and +/- 3.53%, respectively. These data suggest that trained cyclists have the ability to reproduce endurance performance with a CV of approximately 1.0% in a time-trial protocol.(ABSTRACT TRUNCATED AT 250 WORDS)