Reliability of lower extremity functional performance tests

Clinicians routinely have used functional performance tests as an evaluation tool in deciding when an athlete can safely return to unrestricted sporting activities. These practitioners assumed that these tests provide a reliable measure of lower extremity performance; however, little research has been reported on the reliability of these measures. The purpose of this investigation was to determine the reliability of lower extremity functional performance tests. Five male and 15 female volunteers were evaluated using the single hop for distance, triple hop for distance, 6-m timed hop, and cross-over hop for distance as described by Noyes (10). One clinician measured each subject's performance using a standardized protocol and retested subjects in the same manner approximately 48 hours later. The order of testing was randomly determined. Subjects' average and individual scores on each functional performance test were used for statistical analysis. Intraclass correlation coefficients (ICCs) and standard error of measurement (SEM) values based on average day 1 and day 2 scores were used to estimate the reliability of each functional performance test. Intraclass correlation coefficients were .96, .95, and .96, and SEMs were 4.56 cm, 15.44 cm, and 15.95 cm, respectively, for the single hop, triple hop, and cross-over hop for distance tests. An ICC of .66 and SEM of .13 seconds for the 6-m timed hop resulted from limited variability between measurements; however, its small SEM value inferred that the inconsistency of measurement would occur in an acceptably small range. A repeated measures analysis of variance revealed no significant difference ( p > .05) between individual trial scores except for the single hop for distance. We concluded that this difference represented a learning effect not found with the other tests. The results of this investigation demonstrate that clinicians can use functional performance testing to obtain reliable measures of lower extremity performance when using a standardized protocol.