Our study extends the available literature on the survival benefits of physical activity in the very old. We confirmed the suggestion of a beneficial effect of spending time in physical activities on all-cause mortality in elderly adults observed in previous studies and additionally showed that engagement in other less physically demanding activities is associated with decreased risk. Our 28-year follow-up study found that all-cause mortality is lower among participants with daily participation of 15 minutes or more in active activities versus none and with participation of 6 hours or more in less physically demanding activities versus less than 2 hours.
Physical activity has well-documented health benefits, and its relationship with mortality has been explored by a large number of studies (reviewed in 32
). A meta-analysis of 55 analyses (31 studies) reported an RR of death of 0.80 for physical activity (32
). Most found a significantly decreased risk of mortality with increasing levels of physical activity (measured in vastly different ways). The inverse dose–response relationship has been shown in both men and women and in studies conducted in diverse countries (United States, Australia, Britain, Spain, The Netherlands, Denmark, Sweden, Finland, and other European countries) (1
Far fewer studies have focused specifically on elderly adults. The Adventist Mortality Study of 9,484 men found that moderate activity was associated with a protective effect on mortality and decreased with increasing age (2
). The hazard ratios were 0.60, 0.75, 0.75, 0.96, and 0.90 for moderate activity level versus low activity level for age groups 50–59, 60–69, 70–79, 80–89, and 90–99 years, respectively, and 0.63, 0.81, 0.92, 1.11, and 0.92 for high activity level versus low. As part of the Italian Silver Network Home Care project, 2,757 elderly adults with a health problem were followed for at least 1 year (17
). Active participants (physical activity for 2 or more hours per week) were 50% less likely to die compared with those with no or very low levels of physical activity. This inverse relationship was still significant in those greater than 80 years old. Although we found no evidence of an attenuation in the association of physical activity and reduced mortality in late life, we did find that high activity level (1+ hours/day) showed no greater reduction in risk than moderate activity (¼ to ¾ hour/day).
Likewise, few studies have analyzed the effect of less physically demanding activities on mortality in elderly adults and the different classifications used make comparisons difficult. The New Haven site of the Epidemiological Studies of the Elderly classified activities as “social” (attending church, going to movies, theater, or sporting events, playing games, etc.) and “productive” (gardening, preparing meals, shopping, community work, and employment) (10
). In this study of 2,761 men and women aged 65 and older increased participation in either type of activity was associated with decreased mortality. In the Swedish Panel Study of Living Conditions of the Oldest Old, a 4-year follow-up analysis of 463 participants aged 77 and older, leisure activities were classified as “social-friendship” (visiting with friends), “social-cultural” (going to movies, theaters, concerts or museums, eating out, and participating in study groups), “solitary-sedentary” (reading and solving crossword puzzles), and “solitary-active” activities (gardening and engaging in hobbies) (35
). Greater participation in “solitary-active” activities was associated with a significant reduction in mortality. The Aging in Manitoba Study of 2,291 participants aged 67–95 years followed for 6 years, classified these types of activities as “social activities” (visiting family and friends, church-related activities, travel, and sports), “solitary activities” (hobbies, handwork, music, art, theater, reading, and writing), and “productive activities” (volunteer work, housework, gardening, and yard work) (36
). Greater overall activity level was associated with reduced mortality. Individually, only church-related activities and light housework or gardening were significantly associated with decreased mortality.
Current surveillance data indicate that approximately 50% of adults aged 65–74 years and 65% of those aged 75 years and older do not meet recommended levels of regular physical activity (37
). In fact, using a national sample of more than 3,000 adults from the Americans’ Changing Lives study, Shaw and colleagues (39
) found steady declines in leisure-time physical activity, beginning in midlife (about age 33) and growing steeper at progressively older ages. In addition, sex differences in physical activity widened over time with no narrowing in later life. This is consistent with our findings that 2+ hours/day participation in active activities declined more steeply with age in women (19%, 17%, 12%, and 6% for those aged <70, 70–74, 75–79, and 80+ years, respectively) than in men (21%, 20%, 20%, and 12%). Much of the excess decline in leisure-time physical activity among women found by Shaw and colleagues was due to sex differences in time-varying health factors. These may involve differences in the kinds of health conditions that men and women experience as they age. For example, rheumatoid arthritis, a condition which can limit physical activity substantially, is more common in older women than older men; 7% versus 4% in our study. However, our finding that participation in activities had a greater reduction in mortality among those who had cut down or stopped any activity due to illness or injury than those who had not suggests the importance of maintaining activity. Attending to health-related barriers faced by older women and men may help them to maintain an active lifestyle and prolong life.
Although our question about vigorous activity at age 40 was retrospective and subject to recall bias, those were active at age 40 were twice as likely to engage in active activities at older ages than those who did not. Recent promotion of physical activities to improve health (38
) in young and middle-aged adults would thus appear to have not only short-term benefits but also help maintain physical activity in old age.
Like most previous studies reporting on the association of potential risk factors and mortality, our investigation is an observational study. Because in the general population health-promoting habits often cluster, individuals in observational studies who exercise may differ from those who do not in smoking, alcohol intake, medical history, etc. However, adjusting for other risk and potential confounding factors did not materially change the RRs observed for physical activity. Nonetheless, unrecognized and uncontrolled confounders cannot be ruled out in this or any observational study.
We acknowledge several limitations in our study. The indices of physical activities used are crude and self-reported and their reliability and validity were not ascertained. Although our data on potential confounders are also self-reported, previous studies in our population and others support the reliability of medical history of major chronic disease (27
) and of self-reported height and weight (27
). Another limitation is that changes over time in all potential risk factors may affect outcome. Additionally, as our participants were mostly white, highly educated, and of middle social–economic class, they may not be representative of the general population. Although this may limit the generalizability of our results, it offers the advantage of reduced potential confounding by race, education, social–economic class, and presumed access to health care.
This cohort also has the advantages of population-based prospective design, large sample size, and substantial data on important confounders, including factors previously found to be related to mortality and exercise. The long and almost complete follow-up resulted in a large number of outcome events. In addition, we had information on activities not often asked in an exercise survey.