It's not just football.
A new report says too little is known about concussion risks for young athletes, and it's not clear whether better headgear is an answer.
Reports of sports-related concussions have been rising. The Institute of Medicine has taken a closer look, and finds that rates are higher for some sports.
In high school and college, football, ice hockey and lacrosse top the list for male athletes. For females, it's soccer, lacrosse and basketball.
The report cites a gap in information about concussion rates in younger players before high school, and recommends a national system to better track sports-related concussions.
The report stresses wearing proper safety equipment. But it finds little evidence that current helmet designs, face masks and other gear really prevent concussions, as ads often claim.