How can I help my children reduce their risk of sport injuries?

DEAR DOCTOR K: I have a fourth-grader and a middle-schooler. Both enjoy playing sports. Is there anything I can do to reduce their risk of sports injuries?
DEAR READER: You ask an important question. Injuries that result from youth sports are becoming more common -- and the injuries aren't just the expected bumps and bruises that come with being active, either. Doctors are seeing more serious injuries, some of which can lead to lifelong disability. At the same time, regular exercise is really important to a child's health. It also sets patterns for exercise when kids become adults, and that's important to their health later in life.