The aim of this study was to determine the reliability of the squat jump test (SJ) and countermovement jump test (CMJ), in fifty-six children (30 girls and 26 boys) with ages ranging from 6 to 8 years. Each subject performed two evaluation sessions (T1, T2) with seven days between tests. The results show that the CMJ test has a high intratrial reproducibility in T1 and T2 measured through intraclass correlation coefficient (ICC ≥ 0.95). The ICC for the SJ test had a high value (0.99) only in T1. The variability for both tests among children under 9 years of age is higher than those reported for adult subjects in other studies. The intersession reliability was questionable with a high methodical error (ME= 9.86–15.1%, for the SJ and CMJ, respectively) and a significant worsening of the results of CMJ in T2 (p < .05).
Acero, Fernandez-del Olmo, and Sánchez are with the Faculty of Sport Science and Physical Education (INEF Galicia), University of A Coruña, Coruña, Spain. Otero is with the Dept. of Biostatistics and Research Methods, University of Santiago of Compostela, Compostela, Spain. Aguado is with the Faculty of Sport Science, University of Castilla-La Mancha, Spain. Rodríguez is with INEF of Catalunya, University of Barcelona, Barcelona, Spain.