By Ilia Stambler
Exercise is generally considered beneficial for promoting healthy longevity. It is perhaps one of the very few means available to us today to influence our health and longevity. But how much exercise is good for healthy longevity? (What are the dosages)? Which kinds, combinations and time schedules of exercise are good? (What are the regimens?) What dosages and regimens of exercise promote healthy longevity for which people? (What is the personalization?) In particular, what exercise dosages and regimens promote healthy longevity in older people, taking into account their declining functional capacity? “The devil is in the details.”
These still appear to be largely open questions, emphasizing the need for thoughtful research. The openness of these questions is exemplified by historical examples of longevity studies, often showing discrepancies and contradictions in the effects of exercise on longevity for different groups. Some of the examples are listed below, demonstrating the virtual impossibility to speak of longevity benefits of “exercise generally” and emphasizing the need for personalization, and careful and thoughtful study.
One of the earliest examples of such discrepancies can be found, in the beginning of the 20th century, in the works by the American longevity researcher James Rollin Slonaker (1866-1954) considering the relation of exercise to longevity in rats. In Slonaker’s experiment, the animals were subjected to different levels of physical exertion. It was found that, in the exercising group, the more exercise the animals had, the longer they lived. However, the animals that did not exercise at all, but had “usual mobility,” lived longer than those who exercised. The question then arose whether exercise per se is beneficial, or rather which amounts of exercise are beneficial. May physical work shorten life? What would be an exact threshold at which physical work becomes exhaustive, and at which the beneficial effects of stimulation and training are superseded by fatigue and wear and tear?
(Slonaker, J. R., “The normal activity of the albino rat from birth to natural death, its rate of growth, and duration of life,” Journal of Animal Behavior, 2, 20-42, 1912.)
The confusion regarding the role of physical activity for longevity, introduced by Slonaker, has continued in longevity science literature. Generally, physical exercise has been regarded as beneficial for longevity. Yet, there have been conflicting findings.
Thus, it was found that athletes live longer than normal insured men, but shorter than “physically underdeveloped” people. (Louis I. Dublin, “Longevity of college athletes,” Harper’s Monthly Magazine, 157, 229-238, 1928.)
It was also found that athletes live longer in general. (Martti J. Karvonen, “Endurance sports, longevity and health,” Annals of the New York Academy of Sciences, 301, 653-655, 1977.)
And it was also found that athletes live shorter in general. (Peter V. Karpovich, “Longevity and athletics,” Research Quarterly, 12, 451-455, 1941.)
And there were also found no significant differences. (Henry J. Montoye, et al., The Longevity and Morbidity of College Athletes, Indianapolis, 1957.)
The results also varied widely depending on the type of sports, level of athleticism, period of practice, and many other factors. (Anthony P. Polednak (Ed.), The Longevity of Athletes, Charles C. Thomas, Springfield IL, 1979.)
It was also shown that “blue-collar,” physically active workers live shorter than sedentary “white-collar” workers. But this was explained by the assumption that the “white-collar” workers were able to exercise regularly, in a protected environment, and with sufficient rest. (Charles L. Rose and Michel L. Cohen, “Relative importance of physical activity for longevity,” Annals of the New York Academy of Sciences, 301, 671-702, 1977.)
(These works are reviewed in William G. Bailey, Human Longevity from Antiquity to the Modern Lab, Greenwood Press, Westport CN, 1987, “Athleticism and Exercise,” pp. 98-104.)
The general uncertainty about the role of exercise for influencing human longevity, aging and aging-related diseases was well expressed by one of the founders of American institutional gerontology (one of the founders of the US National Institute on Aging) – Nathan Shock, who wrote:
“In no case did the athlete group have significantly different longevity from a random group of college men. However, honor men or intellectuals had a two-year longevity advantage over athletes and the general group of nonathletes. …
In view of the lack of clear evidence of the effect of exercise on the incidence of coronary artery disease, the Task Force on Arteriosclerosis of the National Heart and Lung Institute (1972) concluded that there was not enough evidence to warrant a trial of exercise in the primary prevention of coronary heart diseases. …
aging in the total animal may be more than the summation of changes that take place at the cellular, tissue or organ level. Life of the total animal requires the integrated activity of all of the organ systems of the body to meet the stresses of living… with advancing age, regulatory mechanisms are less effective. Much work remains to be done to identify the mechanisms which are critical in explaining the reduced effectiveness of adaptation, which is associated with aging in the total animal.”
(Nathan Wetherill Shock [1906-1989, National Institute on Aging, NIH, and the Baltimore City Hospitals]. System Integration. In: Finch CE, Hayflick L (eds) Handbook of the biology of aging. Van Nostrand Reinhold Company, New York, 1977, pp 639–665)
The uncertainty has continued. One of the more recent examples in confusing findings is Howard Friedman and Leslie Martin’s The Longevity Project. Surprising Discoveries for Health and Long Life from the Landmark Eight-Decade Study, Hudson Streen Press, Penguin Group, NY, March 2011.
Based on the analysis of a group of 1500 subjects, Friedman and Martin basically suggested that many factors popularly associated with decreased longevity – such as lack of exercise, demanding careers, anxiety, risk-taking, lack of religion, being unmarried, unsociability, pessimism, stress-producing Type A behavior, various dietary taboos – should be taken with a large grain of salt. For example, the more cheerful and relaxed people tended to live shorter than “prudent and persistent” individuals (p. 9). The book also suggests that strenuous exercise does not necessarily lead to greater longevity (pp. 105-106).
Many more such examples of uncertainty can be quoted, altogether emphasizing the need not just for “further research”, but mainly for “further understanding”.
(See also: Ilia Stambler. A History of Life-Extensionism in the Twentieth Century, Longevity History, 2014 http://www.longevityhistory.com/ )
https://www.longevityhistory.com/read-the-book-%20online/#_edn673
