Can physical activity offset the detrimental consequences of sedentary time on frailty? A moderation analysis in 749 older adults measured with accelerometers

Objectives: To determine whether or not and to what extent the association between sedentary time and frailty was moderated by moderate-to-vigorous physical activity in older adults. Design: Cross-sectional. Setting: Community-dwelling individuals. Participants: 749 (403 females and 346 males) white older adults. Measurements: Sedentary time and moderate-to-vigorous physical activity were measured with accelerometers. Frailty was objectively measured using the Frailty Trait Scale. All models were adjusted for age, sex, education, income, marital status, body mass index, moderate-to-vigorous physical activity, and accelerometer wear time. Results: The regression model reported a significant effect of sedentary time on frailty (P < .05). Nevertheless, the results indicated that moderate-to-vigorous physical activity moderates the relationship between frailty status and sedentary time. The Johnson-Neyman technique determined that the estimated moderate-to-vigorous physical activity point was 27.25 minutes/d, from which sedentary time has no significant effect on frailty. Conclusions: Moderate-to-vigorous physical activity is a moderator in the relationship between sedentary time and frailty in older adults, offsetting the harmful effects of sedentary behavior with 27 minutes/d of moderate-to-vigorous activity. Engaging in moderate-to-vigorous physical activities should be encouraged. Reducing sedentary behavior may also be beneficial, particularly among inactive older adults.