Use of the reliable change index to evaluate the effect of a multicomponent exercise program on physical functions.

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Using the reliable change index (RCI), we aimed to examine the effect of a multicomponent exercise program on the individual level. Overall, 270 adults (mean age, 78years) completed a multicomponent physical exercise program (strength, aerobic, gait, and balance) for 40min, 1-2 times per week, continued up to 1year at a daycare center. Effectiveness was assessed using grip, ankle, knee, and hip strength; Timed Up & Go (TUG); Berg Balance Scale (BBS); gait speed; and 6-min walking distance. These were measured at baseline and every 3months thereafter. We calculated the RCI using the data between two-time points (baseline and at 3, 6, 9, or 12months) in each participant and then calculated the mean RCI value across the participants. A paired t-test was also employed to evaluate the effect of the intervention as an average-based statistics. The highest mean RCI values were on ankle plantar-flexion strength, followed by gait speed, hip abduction strength, BBS, knee extensor strength, 6-min walk distance, grip strength, and finally TUG. Paired t-test also revealed significant improvement with moderate effect sizes for ankle plantar-flexion strength (0.504), gait speed (0.413), hip abduction strength (0.374), BBS (0.334), knee extensor strength (0.264), and 6-min walk distance (0.248). Significant but small effect size was seen on TUG (0.183). The RCI is a convenient method of comparing the effect between different assessments, especially at an individual level. This index can be applied to the use of personal feedback.