Is rest-activity rhythm prospectively associated with all-cause mortality in older people regardless of sleep and physical activity level? The 'Como Vai?' Cohort study.

OBJECTIVE: This study aims to test the association of rest-activity rhythm (intradaily variability and interdaily stability) with all-cause mortality in an older adult cohort in Brazil. It also assesses whether the amount of time spent at each intensity level (i.e., physical activity and nocturnal sleep) interferes with this association. METHODS: This cohort study started in 2014 with older adults (≥60 years). We investigated deaths from all causes that occurred until April 2017. Rest-activity rhythm variables were obtained using accelerometry at baseline. Intradaily variability indicates higher rhythm fragmentation, while interdaily stability indicates higher rhythm stability. Cox proportional-hazard models were used to test the associations controlling for confounders. RESULTS: Among the 1451 older adults interviewed in 2014, 965 presented valid accelerometry data. During the follow-up period, 80 individuals died. After adjusting the analysis for sociodemographic, smoking, morbidity score, and number of medicines, an increase of one standard deviation in interdaily stability decreased 26% the risk of death. The adjustment for total sleep time and inactivity did not change this association. On the other hand, the association was no longer significant after adjusting for overall physical activity and moderate to vigorous physical activity. CONCLUSION: Rest-activity rhythm pattern was not associated with mortality when physical activity was considered, possibly because this pattern could be driven by regular exercise. Promoting physical activity remains a relevant strategy to improve population health.

Social Support and Leisure-Time Physical Activity Among the Elderly: A Population-Based Study.

BACKGROUND: Physical inactivity in elderly is a public health problem. The purpose of this study is to describe and test the association between social support and leisure-time physical activity among the elderly. METHODS: A cross-sectional, population-based study with 1,285 subjects (60+ years old) living in a city in southern Brazil was carried out in 2014. Physical activity practice was measured using the International Physical Activity Questionnaire [leisure domain: at least 150 minutes per week of walking + moderate physical activity + 2(vigorous physical activity)], while social support was measured using the Physical Activity Social Support Scale. RESULTS: The prevalence of elderly who reached the recommendations of leisure-time physical activity was 18.4%. The elderly persons who had the company of family or friends to walk had a 2.45 times higher prevalence of reaching the recommendations of physical activity in leisure than those who did not. Those who had company of friends to practice moderate-to-vigorous physical activity (MVPA) were 3.23 times more likely to reach physical activity recommendations than their counterparts. The least common social support was the joint practice for walking and for MVPA. CONCLUSION: Strategies that incentivize family members and friends to provide social support to the elderly for physical activity focusing on joint practice must be encouraged.