Reliability of dynamic strength knee muscle testing in children

The isokinetic knee test is reliable in young individuals in a broad age range between 6 years of age to puberty, but not specifically in the youngest subgroup, in which cooperation may be less dependable. Hence, the purpose of this study was to investigate the reliability of isokinetic knee flexor/extensor muscle torque in a narrow age range: 6-8 years old. The sample consisted of 12 boys tested in three sessions with 3 days of rest between sessions. During each session, two tests were performed with each knee. Intrasession correlation coefficients ranged between .94 and .99 for quadriceps and between .78 and .96 for hamstrings. Interclass correlation coefficients, which express the reliability of a single test, were high (ranging from .85 to .95). Analysis of variance for repeated measurements showed that sixfold repetition of the test had no significant effect on peak torque measurements. These data suggest that the isokinetic knee flexion/extension torque is reliable in boys 6-8 years old.