Validity of the Yo-Yo intermittent recovery test level 1 in assessing or estimating V̇O2max among female soccer players

The Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) has gained large popularity in soccer to evaluate players' ability to perform repeated intense exercise (Bangsbo et al., 2008; Krustrup et al., 2003; Krustrup et al., 2005). However, to date no study has simultaneously evaluated if maximal oxygen consumption (V̇O_2max) could also be accurately assessed (via portable spirometry) or estimated (through an indirect formula based on distance covered) during the YYIR1 in a population of female soccer players. Therefore, a comparison of both direct and indirect V̇O_2max values attained during the YYIR1 with direct V O2max measurements obtained during laboratory testing (gold standard) is still lacking.