The countdown is on for kids heading back to school, and for student athletes, that means gearing up for fall sports.

Orthopedic surgeon Dr. David Litner is Chief of the Houston Methodist Center for Sports Medicine. As head physician for the Houston Astros and team orthopedist for the Houston Texans, he knows the injuries that sideline athletes of all ages.

Unfortunately, fall is a busy time for year for him.

"It seems that most of the kids that tear their ACLs (anterior cruciate ligament), tear them in the first part of the season,” Dr. Litner told Local 2. “Most kids that tear their shoulders, tend to tear them in the first part of the season. We're not really sure why that is, whether it's conditioning or what not. But those are the more common ones that we see."

Dr. Litner recommends agility and jumping maneuvers to decrease the chances of an ACL tear.

"Athletes that are getting ready for football and volleyball tend to focus on lifting weights in the gym, running for conditioning and that's all very important for the foundation,” he explained. “But, it's really the agility, the jumping and most importantly, the landing from a jump that can really train your muscles to help keep you out of trouble."

Dr. Litner said athletes, especially boys, get in the weight room and tend to focus on building up their quadriceps muscles and ignore the hamstrings.

But, he said hamstring strength is just as important when it comes to protecting the body from injury.