From an article on “what’s the best exercise” comes a concise summary of the benefits of moderate exercise:
The health benefits of activity follow a breathtakingly steep curve. “The majority of the mortality-related benefits” from exercising are due to the first 30 minutes of exercise, said Timothy Church, M.D., who holds the John S. McIlhenny endowed chair in health wisdom at the Pennington Biomedical Research Center in Baton Rouge, La. A recent meta-analysis of studies about exercise and mortality showed that, in general, a sedentary person’s risk of dying prematurely from any cause plummeted by nearly 20 percent if he or she began brisk walking (or the equivalent) for 30 minutes five times a week. If he or she tripled that amount, for instance, to 90 minutes of exercise four or five times a week, his or her risk of premature death dropped by only another 4 percent.
Yeah. If you don’t exercise at all, working up to 30 minutes of something (like walking) 5 times a week may very well reduce your risk of death. Increasing beyond that? Not so much.
This isn’t always what you read in the fitness / personal improvement press. Frequently exercise is presented as something that can’t be overdone, or as an obligation to improve one’s health, or to cause weight loss. I disagree. Yes, moderate exercise is generally good for health. No, that does not mean it’s a requirement, or that doing more is necessarily better. Period.
In my case, I have found that if I do stomach crunches regularly, my back doesn’t hurt. I do stomach crunches. I’ve also found that squats and leg lifts prevent knee pain for me, so I do them. Those things matter to me. I know people who do other special exercises and stretches to avoid injury; others love a particular activity, be it swimming or tennis or triathlons or hiking or tai chi or yoga. (I do yoga for fun m’self.)
People tend to assume that someone who does ultramarathons is healthier than someone who walks to work. That isn’t necessarily so. Stronger maybe, or faster on their feet, or more practiced. But healthier? You can’t know. And that’s okay.