While many kids play multiple sports, maybe a different one each season, there seem to be more and more who are deciding at an earlier age that they prefer one sport and therefore "specialize". This seems to be more common in those children who participate in dance, soccer, gymnastics and tennis.
While I have been noticing more and more over-use injuries in younger aged children, a recent sports medicine study supports this. A preliminary report from the sports medicine department at Loyola Univ. School of Medicine found that "kids are twice as likely to get hurt if they play just one sport than those who play multiple sports." It seems that those children who participate in multiple different sports are actually "cross-training" and are using different muscle groups and different movements.. The children who are playing just one sport are typically playing or competing for over 10 hours a week (more than those in multiple sports) and this requires repetitive use of the same muscle groups.
Added on to this repetition is the stress that is incurred to a growing body. 8-16 year old bodies are still in the throes of major developmental changes and growth spurts and are more vulnerable to injury. Their bodies are just not ready to perform at this level every day, year round. They truly have so little down time that their bodies just "tire out" and overuse injuries occur. This is seen with stress fractures in the back, feet, lower legs, as well as with tennis elbow, and knee problems, just to name a few. I have seen stress injuries in almost every area of the body!
The mainstay of treatment for overuse injuries is REST! But there are children as young as 9-10 in my practice who become anxious and guilt ridden when told that they may not participate (in whatever sport that got them to this place) for 4 - 6 weeks so that their body may heal itself. You can't rush rest and the "body is a temple" that needs time to repair, especially in pre-pubertal children.
It would seem that parents should encourage their children to play/experiment with many different activities during their formative childhood years in hopes that injuries will be fewer and that their bodies will have time to grow before specializing in a sport. By high school the body has matured, there is less risk to growth plates while there is still plenty of time to become a "single sport" jock.
I'm Dr. Sue from The Kid's Doctor helping parents take charge.