Background: Cross-sectional evidence exists on the beneficial effects of breaks in sedentary time (BST) on frailty in older adults. Nonetheless, the longitudinal nature of these associations is unknown. This study aimed to investigate the direction and temporal order of the association between accelerometer-derived BST and frailty over time in older adults.
Methods: This longitudinal study analyzed a total of 186 older adults aged 67-90 (76.7 ± 3.9 years; 52.7% females) from the Toledo Study for Healthy Aging over a 4-year period. Number of daily BST was measured by accelerometry. Frailty was assessed with the Frailty Trait Scale. Multiple cross-lagged panel models were used to test the temporal and reciprocal relationship between BST and frailty.
Results: For those physically inactive (n = 126), our analyses revealed a reciprocal inverse relationship between BST and frailty, such as higher initial BST predicted lower levels of later frailty (standardized regression coefficient [β] = -0.150, 95% confidence interval [CI] = -0.281, -0.018; p < .05); as well as initial lower frailty levels predicted higher future BST (β = -0.161, 95% CI = -0.310, -0.011; p < .05). Conversely, no significant pathway was found in the active participants (n = 60).
Conclusions: In physically inactive older adults, the relationship between BST and frailty is bidirectional, while in active individuals no associations were found. This investigation provides preliminary longitudinal evidence that breaking-up sedentary time more often reduces frailty in those older adults who do not meet physical activity recommendations. Targeting frequent BST may bring a feasible approach to decrease the burden of frailty among more at-risk inactive older adults.
Keywords: Aging; Functioning and disability; Longitudinal; Sedentary time; Structural equation modeling.
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