Abstract
BackgroundAge-related accumulation of chronic medical conditions increases disability in older adults. Physical activity potently combats chronic conditions and disability. However, it is unclear whether activity maintenance alleviates the effects of chronic conditions on disability and if this buffering effect differs with age. This study examined whether long-term physical activity can forestall functional limitations in the face of accumulating chronic conditions among middle-aged and older adults.MethodsParticipants (n = 2,119; 54.7% female) were from the Survey of Midlife Development in the United States. Self-reported physical activity, number of chronic conditions, and functional limitations were obtained across 18–20 years. Functional limitations were regressed against the change in chronic conditions, physical activity, and their interaction over time in a multilevel model of change. Baseline age was added as an additional moderator.ResultsFaster accumulation of chronic conditions [B(SE) = 2.08(0.32), p < .001] and steeper declines in activity [B(SE) = −2.29(0.41), p < .001] were associated with greater increases in functional limitations over time. Among those with faster-than-average increases in conditions, those who maintained activity had a slower progression of functional limitations, compared to those whose activity declined more rapidly [B(SE) = −11.18(3.96), p = .005]. Baseline age moderated the buffering effect of activity maintenance; older adults were protected against functional limitations only when conditions accumulated slowly [B(SE) = 0.23(0.08), p = .005].ConclusionThis study provides evidence for an age-dependent buffering effect of activity maintenance on the longitudinal relationship between chronic conditions and functional limitations. Intervention strategies using physical activity to forestall disability should target midlife adults and consider the rate of condition accumulation.
Highlights
Age-related accumulation of chronic medical conditions increases disability in older adults
This study examined the interactive influences among trajectories of physical activity engagement, chronic medical conditions and functional limitations over 20 years among middle-aged and older adults
The results suggest that the trajectories of both chronic conditions and physical activity independently affected change in limitations over time, after controlling for potential confounders
Summary
Age-related accumulation of chronic medical conditions increases disability in older adults. Physical activity potently combats chronic conditions and disability. This study examined whether long-term physical activity can forestall functional limitations in the face of accumulating chronic conditions among middle-aged and older adults. Results: Faster accumulation of chronic conditions [B(SE) = 2.08(0.32), p < .001] and steeper declines in activity [B(SE) = −2.29(0.41), p < .001] were associated with greater increases in functional limitations over time. Baseline age moderated the buffering effect of activity maintenance; older adults were protected against functional limitations only when conditions accumulated slowly [B(SE) = 0.23(0.08), p = .005]. Conclusion: This study provides evidence for an age-dependent buffering effect of activity maintenance on the longitudinal relationship between chronic conditions and functional limitations. Intervention strategies using physical activity to forestall disability should target midlife adults and consider the rate of condition accumulation
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