Test-retest reliability of the lateral step-up test in young adult healthy subjects.

The lateral step-up test is often utilized by clinicians to assess lower extremity performance capabilities. Reliability of the lateral step-up test, however, is not available. Therefore, the purpose of this study was to determine the test-retest reliability of a 15-sec and a 50-repetition lateral step-up test on a .15-m (6-inch) and .2-m (8-inch) step. For each of the 15-sec lateral step-up tests, subjects were asked to perform as many repetitions as possible during the 15-sec time frame, while for each of the 50-repetition lateral step-up tests, subjects were asked to perform 50 repetitions as quickly as possible. Eighteen healthy subjects were studied. Data were analyzed through a repeated measures analysis of variance, intraclass correlation coefficients (ICC) (2, 1), and standard errors of measurement. The ICC values were .90 and .94 for the .15-m and .2-m 15-sec lateral step-up tests and .91 and .96 for the .15-m and .2-m 50-repetition lateral step-up tests, respectively, revealing test-retest reliability to be high for each of the tests. Significant differences, however, were noted between the testing days for each of the 50-repetition lateral step-up tests, indicating that the measures may not be stable. No significant differences were seen between testing days for either of the 15-sec lateral step-up tests. While the results support the use of each of the 15-sec lateral step-up tests as reliable, stable measures of lower extremity performance, caution should be used when interpreting the results of either of the 50-repetition lateral step-up tests if used as demonstrated in this study.