Daily Life Physical Activity Modulates the Effects of an Exercise Program on Lower-Extremity Physical Function in Japanese Older Adults

Decreasing daily life physical activity (PA) outside an exercise program might hinder the benefit of that program on lower-extremity physical function (LEPF) in older adults. The purpose of this study was to investigate how daily life PA modulates the effects of an exercise program on LEPF. The participants were 46 community-dwelling older adults (mean age, 70.1 ± 3.5 years) in Kasama City, a rural area in Japan. All participated in a fall-prevention program called square-stepping exercise once a week for 11 weeks. We evaluated their daily life PA outside the exercise program with pedometers and calculated the average daily step counts during the early and late periods of the program. We divided participants into 2 groups on the basis of whether or not they decreased PA by more than 1000 steps per day between the early and late periods. To ascertain the LEPF benefits induced by participating in the exercise program, we measured 5 physical performance tests before and after the intervention: 1-leg stand, 5-time sit-to-stand, Timed Up and Go (TUG), habitual walking speed, and choice-stepping reaction time (CSRT). We used a 2-way analysis of variance to confirm the interaction between the 2 groups and the time effect before and after the intervention. During the exercise program, 8 participants decreased their daily life PA (early period, 6971 ± 2771; late period, 5175 ± 2132) and 38 participants maintained PA (early period, 6326 ± 2477; late period, 6628 ± 2636). Both groups significantly improved their performance in TUG and CSRT at the posttest compared with the baseline. A significant group-by-time interaction on the walking speed (P = .038) was observed: participants who maintained PA improved their performance more than those who decreased their PA. Square-stepping exercise requires and strengthens dynamic balance and agility, which contributed to the improved time effects that occurred in TUG and CSRT. On the contrary, because PA is positively associated with walking speed, maintaining daily life PA outside an exercise program may have a stronger influence on walking speed. To enhance the effectiveness of an exercise program for young-old adults, researchers and instructors should try to maintain the participant's daily life PA outside the program. Regardless of decreasing or maintaining daily life PA, the square-stepping exercise program could improve aspects of LEPF that require complex physical performance. However, a greater effect can be expected when participants maintain their daily life PA outside the exercise program.