Trajectories of Exercise and Mortality in Late Life
Greater physical activity correlates well with lower mortality in later life. Given the way that human data is collected, and the way in which epidemiological studies are carried out, it is hard to determine causation, however. Is it that exercise is protective, or is it that more robust people both live longer and exercise more often? Fortunately the equivalent animal studies on exercise are unambiguous, and show that exercise does in fact act to improve long-term health and reduce premature mortality. Here, researchers expand on the existing evidence by focusing on trends in physical exercise in later life, and how those trends correlate with mortality. They find the expected outcome, in that a reduction in exercise over time is worse than the alternatives.
Lifelong physical activity (PA) promotes a wide range of health benefits and has long been recognized as an important protective factor for chronic diseases. These beneficial effects consistently translate into lower mortality rates in both men and women. The salutary effects of PA might extend to late life, as it is known to delay the onset of disability and to increase lifespan. Furthermore, PA might be negatively associated with other adverse outcomes such as hospitalization, thereby reducing health care expenditure. Remarkably, at advanced ages, PA levels might surpass other cardiovascular or sociodemographic risk factors that are classically associated with adverse outcomes in younger cohorts.
A common methodological limitation in exploring the association between PA and adverse outcomes in older populations is the use of a single time-point assessment of PA (primarily the baseline PA levels) as the exposure variable, which does not account for the dynamic nature of PA behaviours. It is plausible that prospective trajectories (patterns) of PA levels along time in late life may influence adverse outcomes distinctly as compared with cross-sectional estimates, a hypothesis that remains untested to our knowledge. The main aim of this study is to investigate the existence of different PA trajectories within the Toledo Study of Healthy Aging (TSHA) sample, a Spanish longitudinal population-based study, and to evaluate their associations with adverse outcomes (mortality, disability onset and worsening, and hospitalization).
We found four PA-decreasing and one PA-increasing trajectories: high PA-consistent (n = 566), moderate PA-mildly decreasing (n = 392), low PA-increasing (n = 237), moderate PA-consistent (n = 191), and low PA-decreasing (n = 293). Belonging to the high PA-consistent trajectory group was associated with reduced risks of mortality as compared with the low PA-decreasing group (hazard ratio (HR) 1.68) and hospitalization compared with the low PA-increasing and low PA-decreasing trajectory groups (HR 1.24 and HR 1.25, respectively) and with lower rates of incident (odds ratio (OR) 3.14) and worsening disability (OR 2.16) in relation to the low PA-decreasing trajectory group and at follow-up. Increasing PA during late life (low PA-increasing group) was associated with lower incident disability rates (OR 0.38) compared with the low PA-decreasing group, despite similar baseline PA.