The initial Yo-Yo test served as preparation for the four subsequent experimental Yo-Yo tests (trials). The Yo-Yo intermittent recovery test (level 1) has been described elsewhere (Krustrup et al., 2003). Briefly, the test involves completing a series of 20-m shuttle runs at progressively increasing speed until volitional exhaustion. Consequently, the total distance covered during the initial Yo-Yo test was used solely as the reliability trial for comparison with