THE EFFECT OF HEART RATE PACING VS. CONSTANT POWER PACING ON CYCLING TIME TRIAL PERFORMANCE

Abstract

The advent of the heart rate monitor, and the most recent addition of the portable power unit, cyclist now have two devices from which to pace from. However, there has been no research to demonstrate the benefits of power output pacing vs. HR pacing. PURPOSE To examine the differences in time to completion for a 576 kj (approx. 20Km) time trial (TT), using HR vs. power output (PO), as a pacing strategy. METHODS Eight trained male cyclists (age: 29.4 ± 8.9 yrs; mass: 71.6 ± 8.7 Kg; VO2max: 61.3 ± 6.1 ml/kg/min) each completed three 576 kj time trials on an electronically braked cycle ergometer. The initial TT (TTRPE) was completed with distance covered, as the only feedback given, during which average HR and average power output were calculated. During TTHR subjects were asked to maintain the average HR for the TTRPE ± 3% for the first 518.4 kj (approx 18 km) of the trial, after which the subjects were allowed to complete the remaining 57.6 kj (approx 2 km) at any HR. During TTPO, subjects were instructed to complete 518.4 kj maintaining the average power output from TTRPE ± 3%, with no guidelines for power output in the final 57.6 kj. Upon completion of the initial TTPRE, TTHR and TTPO were completed by each subject in a random order. RESULTS Time to complete the trial was not significantly different in the PO trial vs. the HR trial (35.7 ± 3.7 vs. 35.2 ± 3.9 min.) Average power was not significantly different in the PO trial (275.8 ± 32.7 vs. 279.5 ± 36.2 Watts.) Average HR was significantly higher during the HR trial vs. the PO trial (172.1 ± 10.3 vs. 169.2 ± 6.6 bpm.)(p = .02) Average RPE was not significantly different for the HR trial vs. the PO trial. Power was significantly lower during the 1st quarter of the PO trail when compared to the HR trial (301.6 ± 44.0 vs. 270.1 ± 31.8 Watts) CONCLUSION This data suggest that there is no difference in TT performance while pacing with HR vs. PO. However, pacing with PO did results in significantly lower heart rates.