Relative Importance of Changes in Pacing Strategy and Mean Power Output to Performance

Abstract

INTRODUCTION: Besides mean power output (PO), the distribution of available energy over the race, i.e. pacing strategy, is a critical factor in performance. Modeling performance using an energy flow model provides a tool to study the effect of various determining factors in race performance. In the present study, the model was used to determine the relative importance of variation in pacing strategy and anaerobic PO to performance in self-paced exercise. METHODS: 7 cyclists performed four 1500m ergometer time trials (~2min). Pattern of anaerobic power output was calculated by subtracting aerobic power output from total power output and described monoexponentially. By systematically varying anaerobic energy distribution based on mean data over all trials, keeping total energy constant, performance outcomes of different pacing strategies were determined using an energy flow model. For each subject, fastest (F) and slowest (S) time trials were compared and the relative importance of the measured differences in anaerobic PO & pacing strategy was determined. RESULTS: Difference in final time between F and S was 3.7 ± 2.4s. The faster trials were performed with a higher anaerobic peak power (F: 728.2 ± 126.3 W; S: 593.0 ± 149.5 W), combined with a relatively high, but statistically unchanged anaerobic rate constant (F: 0.049 ± 0.019 s-1; S: 0.036 ± 0.012 s-1), meaning that the most successful pacing strategy was characterized by a short and fast start. The variation in mean anaerobic PO (F: 184.7 ± 22.8 W; S: 162.1 ± 25.5 W) in the present data accounted for 70% of the difference in final time between F and S. The remaining 30% was attributable to differences in pacing strategy. CONCLUSION: About 30% of the difference in final times between the fastest and slowest time trials can be explained by variations in pacing strategy towards a more optimal pacing profile, consisting of an increased peak power combined with a relatively high rate constant. 70% of the difference was explained by variation in anaerobic PO generated during the trial, caused by day to day variation or changes in motivation.