Aerobic fitness testing in 6- to 9-year-old children: reliability and validity of a modified Yo-Yo IR1 test and the Andersen test

This study analysed the reliability and validity of two intermittent running tests (the Yo-Yo IR1 test and the Andersen test) as tools for estimating VO(2max) in children under the age of 10. Two groups, aged 6-7 years (grade 0, n = 18) and 8-9 years (grade 2, n = 16), carried out two repetitions of a modified Yo-Yo IR1 test (2 × 16 m) and the Andersen test, as well as an incremental treadmill test, to directly determine the VO(2max). No significant differences were observed in test-retest performance of the Yo-Yo IR1 test [693 ± 418 (±SD) and 670 ± 328 m, r (2) = 0.79, CV = 19%, p > 0.05, n = 32) and the Andersen test (988 ± 77 and 989 ± 87 m, r (2) = 0.86, CV = 3%, p > 0.05, n = 31). The Yo-Yo IR1 (r (2) = 0.47, n = 31, p