There is an unusually high amount of endurance athletes who get ALS, second only to military personnel. I think, and this is just my thoughts, that people who regularly push their bodies beyond the "normal" point and who do not give themselves proper nutrition are more susceptible to a physical breakdown of some sort. So yes I believe the level of training and racing I did for as many years as I did was a contributing factor. That said I would give anything right now to go out and run a 5K.