I recently ran accross the following article on slowtwitch.com. It is called “Training is No Guarantee of Health”. The article discusses in detail why doing a lot of aerobic training is bad for the body. Basically, too much aerobic training will decrease the immune system and increase the aging process.
These findings support two already-known concepts: 1) overtraining defeats the purpose of exercise and 2) strength training is the best way to keep the body in shape. Too much cardio training tears the body down, whereas resistance training keeps it strong and vibrant.
Prior to reading the article I had already known about the dangers of cardio training. However, I did not know just how bad marathon training is for the body. I have a marathon coming up next month, but after reading this article I will definitely re-think whether I want to run marathons on a regular basis in the future. There is a bright side to this though…I look pretty young for my age, so if I keep running excessively I will start to look older and that way I won’t constantly be carded when I am buying alcohol :).

uh-oh…
but how do you define ‘overtraining’?
I think you look your age.