Duluth, MN (NNCNOW.com) --- Football has always been a game of hitting --- but for Duluth Denfeld senior Kevin Marshall, the hits have now stopped.
"He lowered his head, and I lowered my head," Marshall said. "It was helmet-to-helmet."
Three days later, it was confirmed. Marshall had suffered a sixth concussion in six years, and doctors had seen enough.
"They came back and basically told me I couldn't play anymore," he continued, "that they would never clear me."
Dr. Kenji Sudoh is a sports medicine physician at Essentia Health-St. Mary's hospital in Duluth, Minn. He says it's tough to gauge if any particular patient will suffer from long-term effects, but the possibility is definitely there.
"Right now we don't have great studies that say how many concussions are too many concussions," Dr. Sudoh said. "We know it's a traumatic brain injury, and if you have repetitive traumatic brain injuries it can have long-term effects on your brain function."
"I've felt it now because it's been harder to concentrate and retain information," Marshall said following his latest concussion. "I haven't been able to. Sometimes I have blurred vision."
And it's not just Marshall. A 2013 study funded by the Institute of Medicine says sports and recreation-related traumatic brain injuries fall between 1.6 and 3.8 million per year in the United States.
Still, it's an injury that just recently has been thrust into the national spotlight.
"In the past, I know a lot of them have slipped through because athletes thought that was part of the gig," Essentia Health-St. Mary's athletic trainer Terry Hanson said. "They had headaches and concussive-like symptoms, and they never reported it."
That group includes former NFL star Brett Favre, who told WSPZ radio last month he wasn't even sure how many concussions he'd suffered in his 20-plus seasons of professional football.
"I think after 20 years, God only knows the toll," Favre said. "This was a little shocking to me, that I couldn't remember my daughter playing youth soccer."
The obvious counterargument here is that Favre was a professional.
Risk comes with the reward - and with an estimated net worth of over $100 million, Favre's reward was certainly great.
But then there are kids like Marshall, an unpaid amateur who played his games at Public Schools Stadium instead of the famed Lambeau Field --- but a player all the same who carries that popular "play at all costs" mentality into the game.
"You feel like you don't want to let your team down," Marshall said. "You feel like if you're not on the field you're letting your team down. So you try to do everything in your power to deny, deny, deny, and get back on the field again."
That's exactly the culture among athletes, at nearly every level, that medical experts are trying to change.
Dr. Susan Hoppe, the athletic trainer of the UMD men's hockey team, says she uses the same analogy with every athlete returning from a concussion.
"If they have a shoulder separation, as soon as they have their strength back and aren't more susceptible to injury, we can get them back and they can play with pain," Dr. Hoppe said. "A concussion is the exact opposite of that. We don't want them playing with pain or any symptoms whatsoever."
The most common symptoms associated with concussions are headaches, amnesia, and confusion. Those symptoms can last for days, weeks, or even longer --- and Dr. Sudoh says there's no real way for doctors to tell a patient when, or if, they'll be back to 100 percent.
"Predicting how long it takes to recover from a concussion is very difficult. It's very individualized," Dr. Sudoh said. "One person may take just one week to get back while another person may take several months. We have to let the brain rest, and sometimes it's difficult to adjust our activities with school or work. If we can't completely shut down the activities of our brain, that sometimes will prolong recovery or let symptoms stay around longer."