Factors influencing the performance of young football players in the yo-yo intermittent endurance test (Level 2)

Study aim: To find out whether the ability to accelerate, decelerate and turn may contribute to the performance of young football players during the Yo-Yo Intermittent Endurance Test - Level 2 (YYIEL2).

Material and methods: A group of 239 young male football players from three age categories: under 15 years (U15; n = 102), under 17 years (U17; n = 59) and under 19 years (U19; n = 74) were evaluated in sprint, agility, and intermittent exercise performance. Multiple regression models weighted for maturity status were applied.

Results: Significant (p<0.001) differences were found between the U15 and both other groups in all tests. The YYIEL2 was significantly correlated with 5-m and 30-m sprints and agility (r = 0.361, 0.499 and 0.555, respectively; p<0.001) and the latter 3 variables explained 31% (p<0.001) of the total variance of the YYIEL2 performance, the agility test alone being the strongest predictor (b = 0.56; p<0.001).

Conclusions: Despite the usefulness of the YYIEL2 test used in football to determine aerobic fitness, other factors than O₂max, such as peripheral limitations and the ability to accelerate, decelerate and turn, may influence the performance during the test.