Biodynamics. Effect of pacing strategy on energy expenditure during a 1500-m cycling time trial.

PURPOSE A critical assumption in modeling optimal pacing strategy is that the amount of anaerobic energy that can be produced during a time trial is a constant value, independent of pacing strategy. To test this assumption, the effect of manipulations of pacing strategy on anaerobic work produced during a 1500-m cycling time trial was studied. Additionally, the effect of pacing strategy on aerobic and total work was studied. METHODS Nine well-trained cyclists performed three 1500-m cycle ergometer time trials with different strategies (conservative (SUB), even paced (EVEN), and aggressive (SUPRA)). Anaerobic work, aerobic work, and total work were calculated on the basis of V O2, RER, gross efficiency, and external power output. RESULTS ANOVA showed that total anaerobic work did not differ per strategy (EVEN: 27,604 +/- 1103 J, SUB: 26,495 +/- 1958 J, and SUPRA: 26,949 +/- 2062 J). No differences in aerobic work (EVEN: 28,266 +/- 1623 J,SUB: 27,950 +/- 1418 J, SUPRA: 27,844 +/- 1965 J) were evident, either. Subjects were able to accomplish significantly (P < 0.05) more total work during EVEN (55,870 +/- 2245 J) than during SUB and SUPRA (54,444 +/- 2306 and 54,794 +/- 2402 J, respectively). CONCLUSION No difference in anaerobic and aerobic work was found per pacing strategy. Though relevant for sports performance, the differences in total work were relatively small (approximately 2%), considering the broad range of imposed strategies. The assumption that anaerobic work is a constant value, independent of pacing strategy, seems valid in the range of different strategies that are currently simulated in the energy flow models.

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