[OKSooner]

I know someone who was a runner and got into half marathons and some other stuff back in the day.

He's now having trouble with his feet, of all things. The pleasant young podiatrist showed him the x-rays of his feet, and pointed out a certain curvature of his metatarsal bones.

"At some point you've had stress fractures here, and here.", while pointing at each foot.

[dhs12345]

Sounds about right. And it isn't the actual marathon that is the problem — it is the training necessary to increase the stamina to be able to complete a marathon. A person has to train many times a week for very long distances. That is a huge amount of running on hard surfaces.

It is similar to people lifting a lot of weight to get fit. BTW, weight training alone is not sufficient IMO. You need to add cardiovascular training as well.

So, the best solution is exercise in moderation and balance (a mix of aerobic and anaerobic exercise with an emphasis on aerobic).