Replacing Sedentary Behavior With Physical Activity of Different Intensities: Implications for Physical Function, Muscle Function, and Disability in Octogenarians Living in Long-Term Care Facilities

Background: We investigated the associations of replacing sedentary behavior (SB) with physical activity of different intensities on the physical function of octogenarians living in long-term care facilities. Methods: This pooled study recruited 427 older adults aged 80 years and older (69.1% female; body mass index: 27.53). For 345 participants who provided valid data, we assessed device-measured time spent in SB, light-intensity physical activity (LIPA), and moderate to vigorous physical activity (MVPA). We assessed lower limb physical function, strength, mobility, and disability. We used compositional data analysis to investigate the associations of replacing SB with physical activity on the outcomes. Results: Reallocation of SB to LIPA and MVPA was associated with a higher number of 30-second Chair Stand cycles (LIPA: +0.21, MVPA: +1.81; P<.001), greater peak force (LIPA: +11.96 N, MVPA: +27.68 N; P < .001), peak power (LIPA: +35.82 W, MVPA: +92.73 W; P < .001), peak velocity (LIPA: +0.03 m/s, MVPA: +0.12 m/s; P < .001), higher levels of grip strength (LIPA: +0.68 kg, MVPA: +2.49 kg; P < .001), and less time in the Time Up and Go (LIPA: ???7.63 s, MVPA: ???12.43 s; P < .001). Conclusions: Replacing SB with LIPA or MVPA is associated with physical function and disability of older adults living in long-term care facilities.