It's a bit more than that though. I definitely got plenty of exercise as a child, but my ADHD still manifested in me getting hurt a lot more than my peers, because I either didn't have the impulse control to not do something obviously dumb, or because I would get distracted while playing a game and then get hit in the face with a soccer ball or something as a result. I had a poor summer camp counselor actually start crying to my parents because she felt she was doing her job terribly because I got injured so often. My parents knew that was just how I operated though.

Getting the excess energy out definitely helps with feeling overly-energetic, but it doesn't fix many of the core issues that ADHD causes.