Patterns of Sedentary Behavior and Mortality in U.S. Middle-Aged and Older Adults

Abstract

Background Excessive sedentary time is ubiquitous in Westernized societies. Previous studies have relied on self-report to evaluate the total volume of sedentary time as a prognostic risk factor for mortality and have not examined whether the manner in which sedentary time is accrued (in short or long bouts) carries prognostic relevance. Objective To examine the association of objectively-measured sedentary behavior (its total volume and accrual in prolonged, uninterrupted bouts) with all-cause mortality. Design Prospective cohort study. Setting Contiguous United States Participants 7,985 black and white adults ≥45 years. Measurements Sedentary time was measured using a hip-mounted accelerometer. Prolonged, uninterrupted sedentariness was expressed as mean sedentary bout length. Hazard ratios [HRs] were calculated comparing quartiles 2-4 to quartile 1 for each exposure (quartile cutpoints: 689.7, 746.5, and 799.4 min/day for total sedentary time; 7.7, 9.6, and 12.4 min/bout for sedentary bout duration) in models that included moderate-vigorous physical activity. Results Over a median follow-up of 4.0 years, there were 340 deaths. In multivariable adjusted models, greater total sedentary time (HR [95% CI]: 1.22 [0.74-2.02], 1.61 [0.99-2.63], and 2.63 [1.60-4.30]; P-trend <0.001) and longer sedentary bout duration (HR [95% CI]: 1.03 [0.67-1.60], 1.22 [0.80-1.85], and 1.96 [1.31-2.93]; P-trend <0.001) were each associated with a higher all-cause mortality risk. Evaluation of their joint association showed that participants classified as high for both sedentary characteristics (e.g. high sedentary time [≥12.5 h/day] and high bout duration [≥10 min/bout]) had the highest morality risk. Limitations Participants may not be representative of the general US population. Conclusions The total volume of sedentary time as well as how one accrues sedentary time are both associated with all-cause mortality; suggestive that physical activity guidelines should target reducing and interrupting sedentary time to reduce mortality risk. Primary Funding Source National Institutes of Health

Objectively measured physical activity, sedentary behaviour and all-cause mortality in older men: does volume of activity matter more than pattern of accumulation?

“…22 Additionally, a recent study of older women found that the raised risks of mortality associated with higher sedentary time were fully attenuated after adjusting for MVPA. 27 In our study, each 30 min/day increase in LIPA was associated with a 17% reduction in mortality, which was robust to adjustment for sedentary behaviour and MVPA, suggesting that the increase in LIPA rather than the reduction in sedentary behaviour was most important. In a younger NHANES sample, a reduction in mortality of 16% was found per hour of LIPA.…”

“…Data are from a population-based cohort of community-dwelling older predominantly white British men, so results may not apply to women, other ethnicities or younger men; however, other studies have not found evidence that the associations between PA or sedentary behaviour and mortality differ by gender 17 23 25 26 36 and a recent study of older women finds associations in the same direction as ours, although due to methodological differences it is hard to compare effect sizes. 27 Given that LIPA and sedentary time are highly correlated, it can be difficult to distinguish their effects; we did not use isotemporal substitution analyses as the sedentary behaviour and LIPA were too highly correlated, resulting in problems with collinearity and model convergence. In sensitivity analyses, our findings did not meaningfully change after exclusion of men with mobility disability, prevalent CVD and the first year of follow-up, suggesting findings are not likely to be due to reverse causality.…”

“…4 Recently, prospective cohort studies using bodyworn devices to measure PA report that more time spent in MVPA is associated with lower mortality risks and sedentary behaviour with higher risks. [17][18][19][20][21][22][23][24][25][26][27] However, few address the question of pattern of accumulation of activity rather than total volume. Most of the studies use the US National Health and Nutrition Examination Survey (NHANES) data set, [17][18][19][20][21][22][23] and not all findings are consistent.…”

Challenges of Ageing in Portugal: Data from the EpiDoC Cohort

“…These results are consistent with data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study from the United States, in which middle-aged and older adults spend 77.4% of their time in sedentary behaviours. 40 Other studies found similar results. 39 By contrast, older Norwegians have a more active lifestyle, when compared with the Portuguese population.…”

Physical Activity and Function in Assisted Living Residents

“…Long periods of sedentary activity are common among older adults and have a negative impact on both physical and mental health (Diaz et al, 2017; Dunstan, Thorp, & Healy, 2011; Hamer & Stamatakis, 2014). This is true even for those who meet the guidelines for time spent in moderate level activity.…”