I am an avid marathon runner and training at least 3 times a week before my PCS. After PCS immediately stopped all exercise. Went to see my neurologist who said that it was ok for me to get back on the tread mill with light jogging but nothing intense like a marathon.

I think you really have to listen to your own body. My head just doesn't feel right in order to begin running at all even though my doctor okayed it. I do think especially with a brain injury its important to not do anything streneous or overpush yourself. So I've just begun to do some light stretching and yoga and walking on the treadmill for 10 minutes only.