Reliability and validity of Yo-Yo tests in 9- to 16-year-old football players and matched non-sports active schoolboys

AbstractThe purpose of this study was to examine the test–retest reliability and construct validity of three age-adapted Yo-Yo intermittent tests in football players aged 9–16 years (n = 70) and in age-matched non-sports active boys (n = 72). Within 7 days, each participant performed two repetitions of an age-related intensity-adapted Yo-Yo intermittent test, i.e. the Yo-Yo intermittent recovery level 1 children's test for 9- to 11-year-olds; the Yo-Yo intermittent endurance level 1 for 12- to 13-year-olds and the Yo-Yo intermittent endurance level 2 test for 14- to 16-year-olds. Peak heart rate (HRpeak) was determined for all tests. The distance covered in the tests was 57% (1098 ± 680 vs. 700 ± 272 m), 119% (2325 ± 778 vs. 1062 ± 285 m) and 238% (1743 ± 460 vs. 515 ± 113 m) higher (p ≤ .016), respectively for football-trained than for non-sports active boys aged 9–11, 12–13 and 14–16 years. The typical errors of measurement for Yo-Yo distance, expressed as a percentage of the coefficient of variation (c...