When Gabe Maddern fractured his skull playing touch football during the off-season last winter, the extent of his injury wasn't immediately evident.
"A teammate got in the way, and we collided heads and I fell down," said Maddern, now a 16-year-old junior at Eden Prairie High School. "We both fell down. I got right back up thinking everything was fine, just a normal bump on the head.
"And then I felt dizzy. And I walked to the Activity Center to get a drink, and I came out and they told me I had a seizure."
Maddern suffered a concussion, an increasingly common injury to high school athletes. Some describe it as getting their bell rung. But the Brain Injury Association of Minnesota wants young athletes to start taking the condition more seriously.
The association hopes that by educating teenagers, their parents and coaches about the signs and symptoms of concussions, they'll prevent more athletes from developing long-term health problems.
In Maddern's case, a teacher called an ambulance just to be safe. While it was en route to the high school, his team went ahead with its next game.
Maddern has no memory of his seizure. The only thing he recalls is waking up at Hennepin County Medical Center in Minneapolis two days later.
Doctors told him that he had dodged the worst outcome -- his brain didn't bleed and he didn't experience any dangerous brain swelling. But they said his football career would be on hold until he recovered from the neurological problems caused by his concussion.
So Maddern is on the sidelines this season, hoping he'll be able to play football again during his senior year.
It's an option that Laura Nickel wishes she had. The first year Bethel University student may never play soccer again. Like Maddern, Nickel collided with another player during a high school match last October.
"At the time I didn't know I had a concussion, so I kept playing," she said. "And I played for that whole week in practice. A week later I got hit in the face with a ball that a girl kicked, and got another concussion."
That's the one that ended her soccer career. Repeat concussions are dangerous, especially if they occur before the brain has had a chance to heal from the first concussion. Nickel said there was no mistaking her second concussion.
"It was like fireworks inside my head, and I fell over and I blacked out," she said. "It took me about five minutes to get back up because I was so dizzy."
Nickel was diagnosed with post-concussive syndrome -- a condition where the symptoms of a concussion can last for years or become permanent.
Doctors ordered her to rest her brain completely for three weeks. She didn't go to school, read books or watch television during that time. She improved enough to resume her classes and graduate from high school. But several troubling symptoms haven't gone away.
"It was like fireworks inside my head."
"I'm still sensitive to bright lights and to loud noises. And I still have vertigo every once in awhile," Nickel said. "I used to have it about three times a day. And now it's about once a month. I still have headaches all the time. And they get a lot worse when I have to do a lot of reading or studying."
Nickel said if she had known what to look for it would have been obvious that her first blow to the head was a concussion. She had all the classic symptoms -- vertigo, concentration problems and impaired speech. She even developed a slight stutter.
But her family thought those were all signs that Nickel had caught H1N1 influenza, which was spreading rapidly throughout Minnesota at the time.
David King, executive director of the Brain Injury Association of Minnesota, said if all athletes, parents and coaches become more aware of the signs of brain injury, repeat concussions could be eliminated.
"The good news for us is that second impact -- that's the one that is preventable," King said. "If we can get the message out there and get these athletes sidelined, and give them the chance to heal before they go back in, before they return to play, they're much less likely to have long-term problems."
The association is calling on all Minnesota high school and youth athletic organizations to adopt stringent return-to-play guidelines that protect kids from repeat concussions. Some states have already mandated these types of policies. But King said he hopes Minnesota schools and youth sports groups will voluntarily agree to the guidelines.