Whenever looking at correlations between behavior and lifespan, or behavior and health, one should always ask whether calorie intake or physical activity level could be involved. Both animal and human studies tell us that the effects of both of these items are large in comparison to almost all other commonly varying factors, with smoking being one of the few exceptions to that rule. In recent years, the growing use of accelerometers rather than self-reporting in studies of exercise have revealed that even quite modest physical activity correlates with a sizable difference in outcomes in later life. Animal studies tell us that exercise does in fact cause improvements in health and at least healthy life span if not maximum life span. It is very hard to pull out causation from human statistics, but it is reasonable to arrange one's life on the basis that causation in other mammals matches up with causation in humans in this matter.
Retirement as an institution has interesting correlations with life span, especially in those countries where it is voluntary, and people are not forced into it, pushed out of their own lives by uncaring bureaucrats. More than one set of research results indicates that retirement is bad for health, and there is the suggestion that this might be because of declining physical activity. Certainly it is easy enough to point to correlations between ill health and retirement - people who age more rapidly or become ill and frail will certainly retire at much higher rates. Much of this research goes beyond the event of retirement itself to look at what happens later, however, and that is where suggested causation emerges from the data.
The open access paper I'll point out today might be taken to indicate that most earlier studies of this nature are perhaps overly simplistic. There are many life paths to consider: an obese individual who retires due to ill health is in a very different bracket of influences and outcomes from a thin individual who transitions from a desk job to actively gardening during the day. Some groups of people do actually undertake more physical activity following retirement. The paper itself splits out retirees into a fair number of categories, and it is worth looking through to find the tables and charts. What we might take away from this is a reminder that rejuvenation therapies are on the horizon, some already in early clinical development, and for many of us a few years here or a few years there may wind up being the difference between living to benefit or dying just at the verge of the new era of treatments for the causes of aging.
Participation in physical activity declines with age concurrent to an increasing risk of preventable health conditions like type 2 diabetes. Yet physical activity is widely recognized as crucial for strengthening and maintaining physical and mental health during aging. Some transitions out of the labor market, such as retirement and semi-retirement, may free up time that could be used to (re) engage in physical activity. Retirement can be seen, therefore, as a potentially sensitive period in the lifecourse to target interventions for promoting healthy ageing. Evidence on physical activity during retirement from cross-sectional studies is mixed and limited by the spectre of reverse causality. Some longitudinal studies have the potential to approximate the transition to retirement, so should be regarded as higher quality evidence. Of the longitudinal studies, some have attempted to isolate the impact of retirement on leisure-time physical activity specifically. Others have investigated whether trajectories in physical activity across retirement vary by indicators of socioeconomic circumstances. Findings remain equivocal, however, providing no firm answer on how retirement affects participation in physical activity.
Accordingly, the purpose of this longitudinal study was to examine participation in different intensities of physical activity among people transitioning out of full-time employment to different forms of retirement, while also accounting for transitions to unemployment, part-time work, or disability status. Data was obtained for 5,754 people in full-time employment aged 50-75 from the US Health and Retirement Survey. Logistic regression was used to examine trajectories in twice-weekly participation in light, moderate and vigorous physical activity among those transitioning to part-time work, semi-retirement, full retirement, or economic inactivity due to disability, in comparison to those remaining in full-time employment.
Twice weekly participation in vigorous and light physical activity changed little for those who remained in full-time employment, while moderate physical activity decreased between baseline and follow-up. Differences in physical activity according to transitional categories at follow-up were evident. Baseline differences in physical activity across all intensities were greatest among participants transitioning from full-time to part-time employment compared to those who remained in full-time employment throughout the study period. Those transitioning to unemployment were already among the least physically active at baseline, irrespective of intensity. Those transitioning to full-time retirement were also among the least active. Declines in physical activity were reported for those transitioning to economic inactivity due to a disability. Physical activity increased regardless of intensity among participants transitioning to semi-retirement and full retirement. Light physical activity increased for those transitioning to unemployment, though less change was evident in moderate or vigorous physical activity.
Insufficient physical activity is suggested to cause 6% of coronary heart disease, 7% of type 2 diabetes, 10% of breast cancer, 10% of colon cancer, and 9% of premature mortality. Although finding opportunities to promote the initiation and maintenance of physically active lifestyles is needed across the lifecourse, this study supports previous evidence that indicates the process of retirement as one such time period. Inevitably, the findings raise questions and hypotheses requiring analyses that are beyond the remit of the paper and, in some cases, also the data available. For example, is the rise in physical activity regardless of intensity among people moving into semi-retirement due to less time spent in employment? Why are people who move into part-time work already more physically active than their counterparts who remained in full-time work? Is the rise in light physical activity among people who become unemployed sustained among those who re-enter some level of employment? What factors buffer the potential impact of disability on the substantial decreases in physical activity? What types of activities do people become more or less engaged in and are there differences between transitional groups? To what extent do changes in physical activity coinciding with the transition out of full-time employment reflect personal choices versus any number of possible competing demands upon time, including informal caring and volunteering? This is not an exhaustive list and it is clear that much remains unknown. Yet, the need to promote physical activity in ageing populations remains a pressing concern and these hypotheses warrant investigation in order to target future interventions accordingly.