Thanks so much for such an interesting post. Although I don't have the exact quote or research in front of me, another angle to go with training the brain is to talk about sustained exercise that requires concentration and ADHD. Having been diagnosed with adult ADHD at the age of 33 about a year ago I read as much as I could and there is a strong argument for cardiovascular exercise and its effects on ADHD. It is equivalent to taking Ritalin and Prozak. Coming from running into swimming, I can second your view that swimming requires much more concentration. I generally swim early in the morning unmedicated and it is an excellent way to try and maintain focus, especially on longer swims.