I have seen this type of highly physical child do well in triathlon training, swim team and 5k training (all at the same time). It allows the release of the energy and helps to train focus for a cause. It took about 2 years, but really made a big difference.
Though I have no direct experience, I too have seen such a child do very well with Swim Team (at the advanced levels, he had to train twice a day) and advanced violin lessons. It was a good combination for that child which allowed for a structured release of extra energy and then a disciplined focus in his violin study.
