Most serious head injuries in college football are never reported to team trainers or coaches because the players don't think their symptoms are severe enough to indicate a concussion, according to a new Indiana State University study.

That lack of knowledge could be putting athletes at risk for more severe injury, or even death, researchers say.

"When your head is messed up, you may not know it yourself," said JoEllen Sefton, a doctoral fellow in sports medicine who surveyed 457 players, 38 coaches and eight trainers from eight NCAA Division I-A, I-AA and II colleges.

Coaches, players, athletic administrators and medical personnel have long known the risks of injury to the brain. But Sefton's 2002 survey, to be presented Saturday at the National Athletic Trainers Association meeting in Baltimore, indicates nearly three of every four concussions go unreported.

A concussion is a blow to the head that jostles the brain and can cause brain swelling, blood vessel damage and even death. Symptoms can include headache, confusion, loss of consciousness and nausea.

A study funded in part by the NCAA and published last November by the Journal of the American Medical Association found college players who suffer concussions are more prone to another one, especially if they return to the field too soon. They also become slower to recover from blows to the head, researchers said.

The Indiana State study, published in the April-June issue of the Journal of Athletic Training, gave players a list of symptoms and asked them to identify which were associated with concussions and which were not. It asked players how many of those symptoms they had experienced, and how often they had reported them, after a hit to the head.

Sefton said those surveyed suffered symptoms consistent with concussion 391 times -- 21 percent of them more than once. But 72 percent of the symptoms were not reported, primarily because the athlete did not think the injury was serious, she said.

-- Associated Press