A doctor I work with recently said she was concerned by the increase in lumbar stress fractures she was seeing in young athletes. She said she used to see it mostly in gymnasts but now she was seeing it in teens who play all kinds of sports.
We hypothesized it might be the long hours of practice and tournaments on weekends that sometimes include 6-8 hours of play a day. I also think it may reflect the increasing tendency for parents and teens to "raise the bar," in academics, athletics, everything - to give our children the best chance of success that we can.
To get some more information, and a different perspective, I went to Jolie Bookspan, my favorite Fitness Fixer. Jolie had a couple of interesting hypotheses including an increase in lumbar stresses from severely overarching (increasing inward curve) of the lower back, and some really bad sitting posture habits. In addition, Jolie is concerned that teens are not getting enough exercise or spending enough time in the sun to have the strong muscle and healthy bones that would protect them from these fractures.
Another concern is that the young athletes have typically been experiencing pain for quite a while before seeking care, making the diagnosis and treatment more difficult. Teens should not be experiencing back pain. If your teen complains of back pain, please see his or her doctor.