i firmly believe it. my husband and i see it daily. we own a gym.
one of my husbands clients who has pd had never been upstairs in his house. ( had lived there for a few years) after training with my husband for a few months, this last christmas while he and his wife we entertaining, his wife found him taking their friends on a tour of the upstairs.
i can go on and on. we have many members with pd who have seen great results. it's not a miricle, not a cure, it almost like occupational therapy. reteaches your body.