Exercise As Medicine
Updated: Aug 21, 2019
In the late 1800s and early 1900s, the theory of molecular medicine arose, in which diseases are due to an abnormal chemical reaction in the tissue of concern (be it heart, liver, tumor cells, etc.). Moreover, if one can set that reaction aright, then one can cure the disease. This was a very big change compared to our medical forefathers, who blamed various diseases on miasmas (swamp gas), evil humors, witchcraft and other mysterious entities [Starr]. Molecular medicine magnificently transformed what physicians offer to patients – longer, better lives.
Two former mainstays of good health, exercise and nutrition, fell from favor to become side branches of molecular medicine. All the way back to Hippocrates, physicians had advocated for diet and exercise as paths to health, but they had no idea how diet and exercise work [Hippocrates]. Doctors of antiquity merely observed that good food and physical fitness led to health, well-being and a long life.
But that wasn’t sufficiently “molecular”, so the challenge became one of understanding holistic concepts in terms of biochemistry. At first, that was probably easier for nutritionists because in diseases of dietary deficiency, such as scurvy, beri beri, and rickets, the lack of a single essential element in the diet causes the disease. Such diseases fit the molecular model very well. It took much longer for researchers to understand the molecular biology of exercise.
In 1909, R. Tait McKenzie, the first modern sports medicine physician and also Director of the Department of Physical Education at the University of Pennsylvania, published Exercise in Education and Medicine [McKenzie]. One real debate of his day (and for some 60 years to come) was whether or not exercise was good or bad for the heart.
It was known that athletes had enlarged hearts, but so too did patients with high blood pressure and heart failure. Was heart enlargement always bad, or was it good in the case of an athlete but bad in the case of a patient with heart failure? If so, why? And if exercise enlarges the heart, does exercise make the enlargement of heart failure worse? The prevailing doctrine of the era espoused by none other than Sir William Osler – then medicine’s leading molecular medicine advocate – was that treatment for a heart attack should be a month bed rest (not exercise!) and salt baths [Osler]. It was not until 1968 that Saltin, et al., showed that bed rest is, in fact, very bad for the heart [Saltin].
Over time, researchers discovered the compounds that the body uses to control the circulation, such as acetylcholine and norepinephrine, as well as the receptors for these compounds. Then came the discovery of receptor agonists, antagonists and blocking agents, all of which allowed doctors to stimulate or suppress a patient’s cardiovascular function.
Exercise research became very important, because exercise reveals the effect of these agents on the cardiovascular system. Indeed, the reason exercise itself works is because exercise directly triggers the release of these compounds, stimulating these biochemical pathways. Researchers in other body systems used exercise as a tool to understand how the body works, to discover the compounds the body uses to produce and recover from the need to move.
Because humans must cope with stressors where physical work is required, there isn’t a body tissue or organ that doesn’t respond to exercise by growing stronger. Conditions for which we now know exercise to be beneficial include [2018 PAG Advisory Committee]:
Lower overall risk of death
Fatal heart attacks and strokes
Non-fatal heart attacks and strokes
High blood pressure
Lower risk of cancers
Preventing weight gain
Arthritis (helps pain and functioning)
Fall prevention and fall injuries
Multiple sclerosis (helps walking and functioning)
Lower risk of dementia
Exercise preserves quality-of-life in most chronic diseases and in the elderly, primarily because exercise:
Improves and preserves the ability to be physically independent
Improves and preserves the ability to think (cognitive function)
Most important, exercise has all of these effects. There is no other therapy that does all of that…and the list of proven benefits is growing.
Exercise stimulates the body’s natural mechanisms to grow stronger and adapt to stress. When you take a pill, get a shot or rub on a cream, those chemicals go through your whole body, so you have to take enough drug to get some of it to that right spot, but it’s almost never at the right time or right dose. Most of the medication goes somewhere else and causes side effects. Exercise produces exactly the right chemicals, in exactly the right place where cells and biochemical mechanisms need them, in just the right doses, at just the right time, far better than any team of doctors and nurses could ever do in an Intensive Care Unit.
Thus, even though an exercise prescription is simple, calling for so-many repetitions or minutes of a particular activity, your body turns that into molecular medicine that is very sophisticated and highly coordinated. Enormously better than any pharmacy or medical team can even dream of doing.
Exercise is as good a medicine as you will ever find. Don’t forget to take yours every day.
Next up: Healthy Eating – exercise’s rival for the title of The World’s Best Medicine!
Starr P. The Social Transformation of American Medicine. Basic Books, New York. 1982. ISBN 0-465-07935-0.
Hippocrates. Collected works, edited by: WHS Jones (trans.). Cambridge, Harvard University Press, 1868.
McKenzie RT. Exercise in education and medicine. Philadelphia, W. B. Saunders, 1909.
Mallory GK, White PD, Salcedo-Salgar J. The speed of healing on myocardial infarction: a study of the pathologic anatomy in seventy-two cases. Am Heart J 18:647-656, 1939.
Osler, W. 1909. The Principles and Practice of Medicine: designed for the use of practitioners and students of medicine. 7th ed. New York: D. Appleton & Co.
Saltin B, Blomqvist G, Mitchell JH, Johnson RL Jr, Wildenthal K, Chapman CB. Response to exercise after bed rest and after training: a longitudinal study of adaptive changes in oxygen transport and body composition. Circulation 38(5 (suppl. vii)):VII-1 - VII-78, 1968.
2018 Physical Activity Guidelines Advisory Committee. 2018 Physical Activity Guidelines Advisory Committee Scientific Report. Washington, DC: U.S. Department of Health and Human Services, 2018.