Can Physical Activity Make Up for the Self-Care Disability Effects of Too Much Sitting? A Moderation Analysis in Octogenarians Residing in Living Care Facilities

Physical activity can delay the progression of self-care disability in older adults residing in living care facilities. Nonetheless, older adults residing in living care facilities spend most of their time sedentary and do not meet the physical activity recommendation, which may result in increasing self-care disability in this population group. In this study, we aimed to determine whether the association between sedentary time and self-care disability was moderated by moderate-to-vigorous physical activity (MVPA) in older adults residing in living care facilities. Sedentary time and MVPA were both measured with accelerometers. Self-care disability was assessed with the Barthel Index. A multivariate regression model was used to ascertain the effects of the interaction between sedentary time and MVPA on the self-care disability of participants. The Johnson-Neyman technique was then used to estimate the exact MVPA threshold at which the effect of sedentary time on self-care disability became nonsignificant. We found a significant effect of sedentary time on self-care disability (standardized β=-1.66; 95% CI -1.77 to -1.54, P = .013). Results indicated that MVPA moderates the relationship between self-care disability status and sedentary time (standardized β= 1.14; 95% CI 1.13 to 1.14, P = .032). The Johnson-Neyman technique determined that 51 min/day of MVPA would offset the negative effects of sedentary time on self-care disability. Our results suggest physical therapists should focus on reducing sedentary time alongside physical activity to prevent the progression to dependency in octogenarians residing in living care facilities.