Assessment of Reliability in Isokinetic Testing Among Adolescent Basketball Players

Background. The reproducibility of day-to-day testing of isokinetic concentric and eccentric muscular actions among adolescent basketball players aged 14 to 16 years and relationships of mean within-subject variation in two isokinetic testing sessions with chronological age, biological maturation (estimated age at peak height velocity), training experience, body size, lower-body morphology, and initial strength performance were evaluated.
Material and Methods. The sample included 27 basketball players who completed replicate test sessions of 5 repetitions of reciprocal concentric and eccentric knee extensions and flexions at 60º s^–1. A randomly selected subsample of 8 players completed a third testing session to confirm reliability estimates.
Results. Coefficients of variation (CV) between sessions 1 and 2 ranged from 8.1% to 17.4%, and intraclass coefficients (ICCs) ranged from 0.72 to 0.89. For sessions 1 and 3, CVs ranged from 3.9% to 6.0%, and ICCs ranged from 0.95 to 0.99. The initial level of strength of eccentric knee flexion (r=–0.43) and eccentric knee extension (r=–0.42) were correlated (P<0.05) with eccentric knee extension within-variation between two sessions. Training experience (r=–0.37, P<0.05) and initial values of concentric knee flexion (r=–0.62, P<0.01) were correlated with concentric knee flexion within-subject differences. Within-subject variation of eccentric knee extension was correlated (P<0.05) with chronologic age (r=0.41), estimated age at peak height velocity (r=–0.38), body size (r=0.41 to 0.47), and leg volume (r=0.39).
Conclusions. Familiarization sessions may improve the reliability of concentric and eccentric knee isokinetic strength testing at 60º s^–1 in adolescent basketball players. Age, maturity status, and training experience of young athletes should be considered when testing knee isokinetic strength at 60º s^–1.