Effects of Reallocating Time Spent Engaging in Sedentary Behavior and Physical Activity on Mortality in Older Adults: ELSIA Study

Replacing Sedentary Behavior Time With Physical Activities, Recommended Physical Activity, and Incident Coronary Heart Disease

OBJECTIVE

To prospectively analyze the associations with coronary heart disease (CHD) risk of reallocating time from sedentary behavior to various physical activities using the isotemporal substitution model, particularly according to whether the participants meet the recommended physical activity level.

METHODS

We included 455,298 UK Biobank participants free of CHD at baseline (March 13, 2006, to October 10, 2010). Sedentary behavior time was quantified by summing up the time spent on television watching, computer (not at work), and driving. Physical activities were categorized as daily-life activities (walking for pleasure, light do-it-yourself, and heavy do-it-yourself) and structured exercise (strenuous sports and other exercise).

RESULTS

During a median follow-up of 11 years, 20,162 incident CHD cases were documented. Sedentary behavior time was significantly associated with a higher risk of CHD, independent of physical activity. Replacing 30 min/d of sedentary behavior with an equal time of various physical activities was associated with a 3% to 12% risk reduction of CHD. Replacing 1 h/d of sedentary behavior with different types of physical activities was associated with a 6% to 23% risk reduction of CHD. Sedentary behavior to strenuous sports reallocations showed the largest benefit. Reallocations of sedentary behavior to various physical activities showed particularly greater benefits among those who did not meet the physical activity recommendations.

CONCLUSIONS

Replacing sedentary behavior time with various daily-life activities or structured exercise is associated with significant reductions in CHD risk.

Dynapenia in all-cause mortality and its relationship with sedentary behavior in community-dwelling older adults

The aim of the present study was to investigate the relationship of dynapenia combined with sedentary behavior (SB) on the risk of mortality in older adults living in a Brazilian community. A total of 322 participants aged ≥ 60 years from the ELSIA (Longitudinal Study of Elderly Health in Alcobaça) prospective cohort were included. Dynapenia was diagnosed when the handgrip strength was < 27 ​kg for men and < 16 ​kg for women. The exposure time to SB was assessed considering the total time spent sitting during one day in the week and one day on the weekend. When combined with dynapenia, we derived the construction of four groups: best behavior (absence of dynapenia and low SB), intermediate behavior (absence of dynapenia and high SB; presence of dynapenia and low SB) and worst behavior (presence of dynapenia and high SB). Mortality was assessed by the follow-up time until death and/or censorship. During the 5-year follow-up of the study, 55 participants progressed to death. In the adjusted models, the dynapenia and the time spent exposed to SB were analyzed in a combined way, the older adults with worse behavior (high SB and dynapenia) had higher risk ratios for mortality (hazard ratio 2.46; 95% confidence interval 1.01-5.97) than the best behavior group. Older adults with dynapenia are at greater risk for all-cause mortality, which is aggravated by the addition of longer exposure to SB.