The evidence becomes more and more obvious that man is a running animal and that observation requires that human investigations take that into consideration with many studies. Assuming that couch potatoes are normal can be misleading when exercise of unknown degree is necessary for being normal. It is research on the 30 million or so runners in our country who are closer to normal in physiology that results become most meaningful. Recentaly an ongoing billion dollar study of pregnant women and their offspring until 21 years of age is underway with your and my tax money. If the study concerned normal women the results would be more meaningful. Normal being running.
For example without proper exercise toxic materials ingested by unsuspecting women that may cause problems in couch potatoes could be eliminated by running pregnant woman. A question arises, could in any of a particular type of malady such as autism in the offspring be eliminated in a woman who runs once a week in at least part of her pregnancy?. That example is admittedly not an accepted fact but the question demands exploration.
The question of how much exercise presents itself and the literature is full of opinions as how little is necessary. Runners would be more apt to ask how much is too much? Watching the winter Olympics and the conclusion of events such as male and female cross country races, bodies are seen lying in many positions, panting before finally arising usually with laughter. Was that experience, excessive? I don't think so. I recall a race I ran in Trumbull, Conn. where at the end a police car followed along my side with bells and horn and flashing lights to indicate the arrival of the last contestant. In that excitement along with cheering friends I started my, "sprint" too soon and literally one step before the finish line I collapsed, and helped to my feet by medics on hand for such a case who walked me to their ambulance where in less than 5 minutes I thanked them and left for the after-race festivities. Was that over doing exercise for my 85 year old body? I was in proper condition and suffered not one iota of injury so I don't think that event was overdoing as far as my health was concerned. As far as my ego, that was a different matter. Perhaps the experts will define,"over doing" one day.