Exercise is an evidence-based strategy for preventing falls. However, its efficacy may vary based on individual characteristics, like gait speed. The study examined whether baseline gait speed modified the effects of home-based exercise on subsequent falls among older adults. This is a secondary analysis of a 12-month, randomized controlled trial in community-dwelling adults who were ≥ 70years old and who had fallen within the previous 12months. Participants were randomized to either 12months of home-based exercise (n = 172) or standard of care (n = 172). This study examined intervention effects on fall rates at 6 and 12months stratified by baseline gait speed (slow [<0.80m/s] or normal [≥0.80m/s]) using negative binomial regressions. Baseline gait speed was investigated as a potential modifier of the intervention effects on mobility and cognitive function using linear mixed modeling. At baseline, 134 participants had slow (exercise = 70; standard of care = 64) and 210 had normal (exercise = 102; standard of care = 108) gait speeds. For participants with slow gait speed, exercise reduced fall rates by 44% at 6months (incidence rate ratio = 0.56; 95% CI = 0.33 to 0.95) but not at 12months (incidence rate ratio = 0.63; 95% CI = 0.38 to 1.03) compared with standard of care; for participants with normal gait speed, there was no significant effect of exercise on fall rates at 6 or 12months. Gait speed modified intervention effects; in the exercise group, participants with slow gait showed significant improvements in the Timed "Up & Go" Test at 6months (estimated mean difference = -4.05; 95% CI = -6.82 to -1.27) and the Digit Symbol Substitution Test at 12months (estimated mean difference = 2.51; 95% CI = 0.81 to 4.21). Older adults with slow gait speed had a reduction in subsequent falls in response to exercise at 6months. Gait speed modified the effects of exercise on mobility and cognition. Older adults with slow gait speed may be a target population for exercise-based fall prevention.
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