Yo-Yo Intermittent Recovery Level 2 Test Performance and Leg Muscle Growth in a Six-month Period among Pubescent Soccer Players at Different Stages of Maturity

Abstract

This study examined the relationships between longitudinal changes in data obtained in the Yo-Yo intermittent recovery level 2 test (Yo-Yo IR2), maximal oxygen consumption (_VO 2 max) and leg muscle size and function in pubescent soccer players. Forty-four soccer players with a mean age of 12.8±0.2 years participated, and were classiˆed into three maturational groups (Late, Average and Early) according to their peak height velocity age. The Yo-Yo IR2 anve-jump tests along with measurement of _VO 2 max and thigh muscle volume were conducted on two occa-sions 6 months apart. Performances in the Yo-Yo IR2 for the Late, Average and Early groups were 311±61, 371±88 and 411±72 meters at thêrst measurement, and 389±73, 509±117 and 621±69 meters 6 months later. Consequently, two-way repeated-measures ANOVA revealed a signiˆcant interaction whereby the improvement in Yo-Yo IR2 performance was larger in the Early group (51.3%) than in the Late group (24.8%). Greater increases of thigh muscle volume and the result of thêve-jump test were found in the Early group, and these were correlated sig-niˆcantly (r＝0.52, pº0.05; r＝0.39, pº0.05) with improvement of Yo-Yo IR2 performance. In contrast, there was no relationship (r＝－0.02, n.s.) between the increments of _VO 2 max and Yo-Yo IR2 performance. These results suggest that performance in the Yo-Yo IR2 is aŠected by maturity to a great extent, early-maturing players having an advantage in terms of leg muscle development.