Streeper, T., Peiffer, J., Faria, I. E., Quintana, R., & Parker, D. L. (2006).The effect of pacing strategy on O2 deficit during the first 5 Km of a 20 Km cycling time trial. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1534.

This study determined if pacing by heart rate causes a higher O2 deficit compared to pacing by power output or rating of perceived effort pacing. Highly trained cyclists (N = 7) served as Ss. Prior to completing the time trials, each S underwent a submaximal test that included 5-minute stages at 100, 150, and 200 Watts. From the power-VO2 relationship, the O2 demand for the first 5 Km of the time trial was calculated based on the average power output. The first of the three time trials was conducted without feedback. The average power and HR during the first trial were used to pace the Ss during their subsequent trials. During the first 5 Km of each time trial, expired gas was collected to determine the oxygen cost of that part of the exercise. The difference between the calculated oxygen demand and the actual oxygen cost represented the oxygen deficit.

The calculated oxygen deficits for the pacing strategies were not significantly different. However, heart rate and rating of perceived exertion were significantly different between pacing strategies. Heart rate was significantly lower when paced by power compared to pacing by heart rate or rating of perceived exertion. Similarly, rating of perceived exertion was significantly lower when paced by power compared to pacing by heart rate or rating of perceived exertion.

Implication. A pacing strategy for the first 5 Km of a 20 Km time trial does not alter oxygen deficit despite differing power output depending on the strategy. Pacing by power appears to induce a lower heart rate and perceived effort than pacing by concentrating on heart rate or perceived exertion. It would appear to be best to have athletes concentrate on their perception of power production when stipulating the content of a pacing strategy.

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