The Effects of Pace Variation on Cost of Running in Trained Runners

Abstract

The cost of running (CR), an important determinant of running performance, is usually measured during constant speed running. However, constant speed does not reflect the nature of competitive races in which stochastic variations in pace often occur. PURPOSE: This study was designed to evaluate whether variations in running speed influence CR in trained runners. METHODS: Twenty well-trained runners (12 m, VO2max=73±7 ml/kg; 8f, VO2mx=57±6 ml/kg) completed an incremental test to determine VO2max & ventilatory threshold (VT). Subsequently, they ran four 6-min bouts at an average speed ∼90% VT. Each interval was run with minute to minute pace variation around the subject’s average speed. The CR was measured over the last 2-min. The coefficient of variation (CV) of running speed was calculated to quantify pace variations; ± 0.0 m·s-1 (CV=0%), ± 0.04 m·s-1 (CV=1.4%), ± 0.13 m·s-1(CV=4.2%), and ± 0.22 m·s-1(CV=7%). RESULTS: No differences in CR, HR, RPE, or blood lactate (BLa) were found amongst the variations in running pace. CONCLUSION: Contrary to our hypothesis, pace variation, within the limits often seen in competitive races did not affect CR when measured at a running speed below VT.