Michael Waltrip doesn't have an exact count of the concussions he has sustained over his NASCAR career. He knows it's more than 10.

Safety improvements since Dale Earnhardt's death in 2001 have greatly reduced the chances of a driver getting a head injury, and NASCAR officials have taken steps to better identify and treat concussions. But Waltrip knows that won't undo all those hits he took in the 1980s and `90s.

Stories about NFL players having serious health problems after they retire has caught the attention of NASCAR veterans such as Waltrip, Jeff Burton and five-time champion Jimmie Johnson. Waltrip says, "I don't know what that means to me in 10 years. But I know it's a concern."

NASCAR officials aren't aware of widespread concussion-related health problems in former drivers.