Hettinga, F. J., De Koning, J. J., Meijer, E., Teunissen, L, & Foster, C. (2007). Effect of pacing strategy on energy expenditure during a 1500-m cycling time trial. Medicine and Science in Sports and Exercise, 39, 2212-2218.

[This abstract is included although it does not involve swimmers as subjects. It has very important implications for completing swimming races.]

"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". [The effect of pacing strategy on aerobic and total work also was studied.] Well-trained cyclists (N = 9) performed three 1500-m cycle ergometer time trials with different strategies (conservative, even-paced, and aggressive). Anaerobic work, aerobic work, and total work were calculated on the basis of VO2, respiratory exchange ratio, gross efficiency, and external power output.

Total anaerobic work and aerobic work did not differ between strategies. Ss were able to accomplish significantly more total work during the even-paced strategy compared to the conservative or aggressive strategies. The differences in total work were relatively small (~2%), considering the broad range of imposed strategies.

Implication. There were no differences in anaerobic and aerobic work expenditures among conservative, even-paced, or aggressive pacing strategies. The assumption that anaerobic work is a constant value, independent of pacing strategy, seems valid in the range of different strategies currently simulated in the energy flow models.

[This study shows why it is silly to go out too fast in an event because that uses up anaerobic capacity leaving less for the latter part of the race. On the other hand, going out too slow does not leave "extra" performance capacity for a finishing effort. For all practical purposes, the total amount of anaerobic and aerobic energy that can be applied to an event is fixed. The most economical use of those finite energy sources is through even pacing, whether in anaerobic or aerobic dominated events. Any deviation from even-pacing (e.g., "taking it out faster") will result in a worse performance than is possible with a consistent-pacing strategy that allows the total task to be completed. The task of completing a performance such as a swimming race is to complete the event with even-paced swimming so that all energy resources are spent at the moment of activating the touch-pad.]

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