Patterns of sedentary and active time accumulation are associated with mortality in US adults: The NHANES study

Abstract

PurposeSedentary behavior has become a public health pandemic and has been associated with a variety of comorbidities including cardiovascular disease, type 2 diabetes, and some cancers. Previous studies have also shown that excessive amount of sedentary behavior is associated with all-cause mortality. However, no studies investigated whether patterns of sedentary and active time accumulation are associated with mortality independently of total sedentary and total active times. This study addresses this question by i) comparing several analytical ways to quantify patterns of both sedentary and active time accumulation through metrics of fragmentation of objectively-measured physical activity and ii) exploring the association of these metrics with all-cause mortality in a nationally representative US sample of elderly adults.MethodsThe accelerometry data of 3400 participants aged 50 to 84 in the National Health and Nutrition Examination Survey 2003-2006 cohorts were analyzed. Ten fragmentation metrics were calculated to quantify the duration of sedentary and active bouts: average bout duration, Gini index, average hazard, between-state transition probability, and the parameter of power law distribution. The association of these fragmentation metrics with all-cause mortality followed through December 31, 2011 was assessed with survey-weighted Cox proportional hazard models.ResultsIn models adjusted for age, sex, race/ethnicity, education, body mass index, common comorbidities, and total sedentary/active time, four fragmentation metrics were associated with lower mortality risk: average active bout duration (HR=0.72 for 1SD increase, 95% CI = 0.590.88), Gini index for active bouts (HR = 0.75, 95% CI = 0.64-0.86), the parameter of power law distribution for sedentary bouts (HR = 0.75, 95% CI = 0.63-0.90), and sedentary-to-active transition probability (HR = 0.77, 95% CI = 0.61-0.96), and four fragmentation metrics were associated with higher mortality risk: the active-to-sedentary transition probability (HR = 1.40, 95% CI=1.23-1.58), the parameter of power law distribution for active bouts (HR = 1.33, 95% CI = 1.16-1.52), average hazard for durations of active bouts (HR = 1.32, 95% CI = 1.18-1.48), and average sedentary bout duration (HR =1.07, 95% CI = 1.01-1.13). After sensitivity analysis, average sedentary bout duration and sedentary-to-active transition probability became insignificant.ConclusionLonger average duration of active bouts, a lower probability of transitioning from active to sedentary behavior, and a higher normalized variability of active bout durations were strongly negatively associated with all-cause mortality independently of total active time. A larger proportion of longer sedentary bouts were positively associated with all-cause mortality independently of total sedentary time. The results also suggested a nonlinear association of average active bout duration with mortality that corresponded to the largest risk increase in subjects with average active bout duration less than 3 minutes.

Modeling Temporal Variation in Physical Activity Using Functional Principal Components Analysis

“…We hypothesized that a higher L 2 norm would be associated with a healthier profile. This is based on evidence [7,8] that it is better to exercise multiple times in a day in short bouts of time, rather than to exercise just once for a long stretch of time. There has been growing literature investigating how patterns of sedentary and active time accumulation are associated with all-cause mortality independently of total sedentary and total active times.…”

“…There has been growing literature investigating how patterns of sedentary and active time accumulation are associated with all-cause mortality independently of total sedentary and total active times. Studies show that a larger proportion of longer sedentary bouts are positively associated with mortality, suggestive that physical activity guidelines should target not only reducing but also interrupting sedentary time to reduce mortality risk [7,8].…”

Active-to-Sedentary Behavior Transitions, Fatigability, and Physical Functioning in Older Adults

“…Although both individuals may accrue similar amounts of active and sedentary time over a typical day or week, the number of transitions between active and sedentary states, or degree of activity fragmentation, differs dramatically. Extracting information on activity fragmentation from accelerometry data may thus provide a new and more informative criterion to identify individuals earlier in their transition from moderately active to largely sedentary (14,15).…”

“…The purpose of this article is to introduce an index of activity fragmentation, the Active-to-Sedentary Transition Probability (ASTP) (14,15), as an early marker of fragmented PA, diminished reserve capacity, and declining functional status in older adults. ASTP is easy to calculate, interpret, and translate across accelerometer devices and studies, which may improve cohesiveness across accelerometer-based research.…”

“…ASTP is easy to calculate, interpret, and translate across accelerometer devices and studies, which may improve cohesiveness across accelerometer-based research. Although similar fragmentation indices have been used to assess sleep quality (14,16,17), to the best of our knowledge, they have not been considered as an informative feature of daily PA in older adults. To provide proof of concept, we examined the association between ASTP and established measures of fatigability (18,19), endurance capacity (20,21), and functional performance (2,22) in well-functioning older adults participating in the Baltimore Longitudinal Study of Aging (BLSA).…”