Bailey writes in the 5/4/09 issue http://www.newsweek.com/id/195086/page/2 of walks the President has taken(that give the Secret Service heart attacks). “He likes solititude, where he can just take a moment, collect his thoughts and breathe”,
 says a close Obama friend.”  At Camp David, “There’s lots of open space where he can go for a walk and clear his mind,” says Valerie Jarrett, a senior White House aide and longtime friend of the Obamas.”

I imagine that all Presidents relish breaks from the intense demands of that role but if Obama is indeed an introvert, I imagine these breaks are critical. Walks and basketball sound like good re-energizers to me.