Greater Stance Time Variability is Associated with Lower Step Activity in Older Adults

Abstract

Previous research has shown that older adults with greater gait variability are at a higher risk for falling. Falls increase fear of falling and may subsequently result in mobility disability manifesting as decreased physical activity. Physical activity is commonly gauged from continuous step activity monitoring. While decreased step activity has been associated with impaired gait, the associations between gait variability and step activity are not understood. PURPOSE: To examine the relationship between gait variability and step activity in older adults. METHODS: Spatiotemporal gait parameters were recorded for 19 healthy older adults (mean age 74.5 ± 6.3 years; 9 males/ 10 females) walking at a normal walking speed across a GAITRite walkway for 5 trials. Step activity (# of steps) was collected using a research-grade step activity monitor for 7 consecutive days. Average number of steps for the 7 days was used. Coefficient of variation (defined as % of SD over mean) of gait speed, stride length, step width, swing time, stance time and double support time were calculated. Pearson’s and Spearman’s correlation coefficients were used based on normality to determine the relationship between gait variability and step activity. RESULTS: Stance time variability showed significant moderate inverse correlation with step activity (rho = -0.482, p = 0.036). Swing time variability showed moderate inverse correlation with step activity with a trend towards significance (r = -0.451, p = 0.052). Variability of gait speed (rho = -0.349, p = 0.143), stride length (r = -0.3, p = 0.212), step width (rho = -0.088, p = 0.721), and double support time (rho = -0.249, p = 0.304) showed weak inverse but not significant correlation with step activity. CONCLUSION: In general, gait variability seems to be inversely related to step activity in older adults meaning those with greater gait variability showed lower step activity. In particular, stance time variability has earlier shown to be critical in identifying older adults with mobility disability and those older adults at risk for future disability. Our finding of decreased step activity in those older adults with increased stance time variability suggests that step activity monitoring could provide surrogate and complimentary measures to identify mobility disability in older adults.