Relationships and agreement between Yo-Yo intermittent recovery test level 1 performance and laboratory VO2max in adolescent male soccer players: roles of maturity status, playing position, and running economy.

BACKGROUND

Accurate assessment of aerobic fitness is essential in youth soccer. The Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) provides a practical estimate of maximal oxygen uptake (VO2max), but its agreement with laboratory values across maturity stages remains uncertain.

AIM: To examine the relationship and agreement between YYIR1 performance and laboratory-measured VO2max in adolescent male soccer players, and to assess whether biological maturation, playing position, and running economy (RE) affect estimation consistency.

SUBJECTS AND

METHODS

Twenty-three players (13.7 ± 0.5 years) completed YYIR1 and laboratory treadmill tests (LTT). VO2max was measured during LTT and estimated from YYIR1 performance. Effects of biological maturation [pre-, circa-, post-peak height velocity (PHV)], position, and RE were analysed.

RESULTS

YYIR1 underestimated VO2max by 5.2% versus LTT (p < 0.001) but showed strong correlation (r = 0.82). Bland-Altman analysis indicated acceptable agreement. Estimation consistency was higher in pre- and circa-PHV players, though subgroup sizes were small. Maturation, position, and RE had no significant effects.

CONCLUSIONS

YYIR1 is strongly associated with laboratory VO2max but systematically underestimates it. Coaches may use YYIR1 distance to monitor intermittent endurance, while interpreting estimated VO2max with caution. Larger, maturity-balanced samples are needed to clarify subgroup differences and improve youth-specific prediction accuracy.