A new clinical test of dynamic standing balance in the frontal plane: the side-step test

Objective: To confirm retest reliability for the side-step test and to investigate the validity of the side-step test by correlating performance on this test with that on other commonly used measures of balance and mobility. Setting: Katta Public Hospital, Miyagi, Japan. Design: Cross-sectional study. Intraclass correlation coefficient was examined by calculating the intra-rater reliability of the side-step test. Moreover, the validity of the test was examined by correlating maximum side-step length with gait parameters. Subjects: This study recruited 28 hemiplegic subjects ( 17 with left-sided hemiplegia and 11 with right-sided hemiplegia). Measures: We measured balance ability and walking ability as follows: dynamic balance ability was assessed from maximum side-step length from the side-step test, static balance ability from one-footed standing duration, and walking ability from maximum walking speed, stride length and cadence. Balance ability was measured on both the affected and unaffected side. Maximum side-step length was standardized in terms of lower extremity length. Results: Intraclass correlation coefficient of maximum side-step length was 0.97 bilaterally. There was a high linear correlation between maximum side-step length and both maximum walking speed and stride length; Pearson's product-moment correlation coefficient ranged from 0.84 to 0.89. One-footed standing duration was significantly correlated with maximum side-step length, maximum walking speed and stride length, and these relationships were non-linear. Conclusion: The reliability and validity of the side-step test was confirmed.