"Rock Center" How far is too far?

I saw this interesting story on Rock Center. While not about soccer, it is about extreme dedication of two young girls to another sport- distance running. At the 6 1/2 minute mark the experts weigh in about overuse and burnout. I thought it was interesting that these girls bodies seem fine, but I would love to have a follow up on them in 10 years to see if they are still at the sport or if Dad has caused them to burnout. I think he'd be considered extreme even in North Texas.

Their mom had a good perspective, "One thing just can't be your whole world."

http://www.nbcnews.com/id/21134540/vp/50751241#50751241