Effect of stride count on the validity and reliability of autocorrelation-based gait variability variables in older adults requiring long-term care

[Purpose] In this study, we aimed to investigate the effects of stride count on the values, validity, and test-retest reliability of autocorrelation-based gait variability variables in older adults requiring long-term care. [Participants and Methods] Thirty participants walked along a 20-meter walkway with a triaxial accelerometer attached to the trunk. The experimental protocol included two walking sessions, each consisting of two consecutive trials. Autocorrelation coefficients were derived from trunk acceleration signals while varying the stride count from 2 to 10 in one-stride increments. We analyzed the influence of stride count on the absolute differences between autocorrelation coefficients and their 10-stride reference values. Additionally, for each stride count, we assessed correlations between autocorrelation coefficients and age-related outcomes, as well as the test-retest reliability of these coefficients. [Results] Absolute differences in autocorrelation coefficients decreased as stride count increased. Variations in stride count influenced age-related outcomes associated with autocorrelation coefficients. Test-retest reliability improved with increasing stride count. [Conclusion] These findings indicate that changes in stride count affect the values, validity, and test-retest reliability of autocorrelation-based gait variability variables in older adults requiring long-term care.