On the flip side, is there ever a point when you can exercise too much? I train for tri's and marathons, so having daily workouts of 2-4 hours is pretty normal for me. I do limit my self to one shallow dive, the day before any big effort. I also pretty much stick to diving Nitrox because, it seems like a safer bet with the daily stress that I put on my body. That being said, I have always wondered about DAN's cautions about diving and streneous exercise. Seeing A.G. do the tri made me feel a little better, that I wasn't too far off.