This reply was originally posted by user Lean~In in ADDitude’s now-retired community.
“When kids exercise, the amount and mix of chemicals called neurotransmitters their brain releases change. Neurotransmitters include dopamine, which is involved with attention. The stimulant medicines used to treat ADHD work by increasing the amount of this same chemical in the brain.”
Exercise for Children With ADHD — WebMD
http://www.webmd.com/add-adhd/childhood-adhd/exercise-for-children-with-adhd_WebMD
This is the #1 answer via Google, tonight.