But around 400 BC Hippocrates (whoever he/they was/were) clearly observed, knew, and stated that moderation in all things is good for health and longevity, and that exercise is part of that. 500 years later (yet still 2000 years ago), Galen was also very clear about the same points, and this from his own very extensive observation. Yes! "Evidence-based medicine" isn't new!
|Hippocrates; Rubens engraving; Wikipedia|
If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health.
Eating alone will not keep a man well; he must also take exercise. -Hippocrates
And, Galen's view, as described by Jack Berryman in "Motion and rest: Galen on exercise and health" (The Lancet, vol 380:9838, pp 210-11):
Galen (c 129—210 AD), who borrowed much from Hippocrates, structured his medical “theory” upon the “naturals” (of, or with nature—physiology), the “non-naturals” (things not innate—health), and the “contra-naturals” (against nature—pathology). Central to Galen's theory was hygiene (named after the goddess of health Hygieia) and the uses and abuses of Galen's “six things non-natural”. Galen's theory was underpinned by six factors external to the body over which a person had some control: air and environment; food (diet) and drink; sleep and wake; motion (exercise) and rest; retention and evacuation; and passions of the mind (emotions). Galen proposed that these factors should be used in moderation since too much or too little would put the body in imbalance and lead to disease or illness.
The authors looked at studies of the effect of exercise on mortality from heart disease, chronic heart failure, stroke or diabetes and found that exercise was either as good as the standard drug treatment or better, except in the case of chronic heart failure. The results show that exercise can be very effective, although medicine is the usual treatment prescribed (naturally).
The results also underscore how infrequently exercise is considered or studied as a medical intervention, Dr. Ioannidis said. “Only 5 percent” of the available and relevant experiments in his new analysis involved exercise. “We need far more information” about how exercise compares, head to head, with drugs in the treatment of many conditions, he said, as well as what types and amounts of exercise confer the most benefit and whether there are side effects, such as injuries. Ideally, he said, pharmaceutical companies would set aside a tiny fraction of their profits for such studies.
But he is not optimistic that such funding will materialize, without widespread public pressure.The bottom line is that we already know exercise is good for you, don't we?** It is problematic that we yet need 'far more information', the usual researcher's plaint. How many details do we need to know about, already knowing that they are largely ephemeral, when there are actual serious unanswered disease questions that we might study? If half or more of diseases are in a sense treatable, preventable, or delayable with exercise rather than drugs, MRIs and CAT scans, surgery or other approaches, then why do we still allow doctors to meddle as much as they do? Why do we still have to spend public funds, essentially to feed schools of public health, to keep on doing what are essentially retreads of the same old studies (with fancier and costlier statistical packages and other exciting technologies to make us seem wise and innovatively insightful)--when there are real, devastating disease problems with real unknowns that could be addressed more intensely?
This is not to mention how much disease would be reduced if we had the societal guts to address poverty. Real unsolved disease problems may be harder to design studies to understand, actually requiring new thinking rather than just designing some new sampling and questionnaires and the like. But at least it would be a more real kind of 'research'.
One answer is that this is how the system, and what is basically its rote means of self-perpetuation works. Science is a social phenomenon not just an objective one. An institutionalized system doesn't insist on moving beyond essentially safe problems that we have a sufficient knowledge of, to face up to ones we don't yet understand. That's riskier for professors needing salaries and publications, and administrators needing the overhead funding. It's part of the fat in the system.
And fat, as we've known since Hippocrates, isn't good for you!
** Actually, despite this post, no, we don't really know this that quite as clearly as you might think! We do certainly have lots of good mechanistic and physiological reasons why exercise is good, but some fraction of the association of exercise with health may be due to confounding: those who exercise are already healthier than average, or know or care more bout health, or they wouldn't do it (e.g., if they were too overweight, or had troublesome joints, etc.). So those who exercise are not a random sample. Is it the exercise itself that does them good? In any case, Galen thought so: he went to the gym regularly because he knew it was good for him!