An examination of a modified Yo-Yo test to measure intermittent running performance in rugby players

Abstract

This study examined how starting each shuttle in the prone position altered the internal, external and perceptual responses to the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1). Using a randomized crossover design, 17 male rugby players completed the Yo-Yo IR1 and prone Yo-Yo IR1 on two separate occasions. External loads (via microtechnology), , heart rate (HR) and rating of perceived exertion (RPE) were measured at 160, 280 and 440 m (sub-maximal) and when the test was terminated (peak). The pre-to-post change in blood lactate concentration (Δ[La]b) was determined for both tests. All data were analysed using effect sizes (ES) and magnitude-based inferences. Between-trial differences (ES ± 90% CL) indicated that total distance was most likely lower (−1.87 ± 0.19), whereas other measures of peak external load were likely to very likely higher during the prone Yo-Yo IR1 (0.62–1.80). Sub-maximal RPE was likely to most likely higher (0.40–0.96) and peak RPE very likely higher (0.63 ± 0.41) in the prone Yo-Yo IR1. The change in [La]b was likely higher after the prone Yo-Yo IR1. Mean HR was possibly lower at 440 m (−0.25 ± 0.29) as was peak HR (−0.26 ± 0.25) in the prone Yo-Yo IR1. , and were likely to very likely higher at 280 and 440 m (ES = 0.36–1.22), while peak values were possibly to likely higher (ES = 0.23–0.37) in the prone Yo-Yo IR1. Adopting a prone position during the Yo-Yo IR1 increases the internal, external and perceptual responses, placing greater emphasis on metabolically demanding actions typical of rugby.