In a recent survey by Sporting News, more than half the players polled said they would hide symptoms to keep playing, and for good reason. A concussion can cost you your starting spot or, in the case of Greg McElroy of the Jets, your moment to shine .

Alex Smith of the 49ers learned the job-threatening implications of a concussion the hard way. When a concussion sidelined him earlier this season, the replacement quarterback Colin Kaepernick played well and took over his starting role. Now Kaepernick is flourishing while Smith watches from the bench.

With the mouth guards there's no hiding or lying about hits. The team wears the mouth guards at all games and practices so that researchers can generate a comprehensive database of every impact they sustain. The sensors measure linear and angular acceleration—how fast the head is moving in one direction and rotating. The sensors may sound high tech, but actually, you might have some in your pocket right now. They are the same ones used in the iPhone 5.

Camarillo says the mouth guards have already captured some startlingly hard hits, like the one that ended the season for a wide receiver. That collision registered an acceleration of 150 Gs, that's 150 times the acceleration gravity. “Pretty serious business,” he says, “a standard boxing punch is probably between 10-20 Gs.

That's just acceleration in one direction. The player's head was also spinning at 2000 degrees per second—which means his head would have rotated five and a half times in one second if it weren't anchored to the neck. While it has long been suspected that this kind of angular acceleration plays a role in concussions, Camarillo says no one has gathered data on it. What's more disturbing is that angular acceleration has been completely ignored when it comes to football safety measures.

The standard industry lab test for helmets is basically a plunger that smashes a helmet down onto a hard surface. The test hasn't changed much since it was first developed back in 1973 by NOCSAE, The National Operating Committee on Standards for Athletic Equipment. The test doesn't account for angular acceleration at all. “The device,” Camarillo says, “doesn't have any kind of neck.”

A number of research groups are conducting similar studies by putting sensors in the helmets but athletic trainer Anderson argues that the mouth guards give more accurate results. He says the initial data has already revealed something new. Some hits they used to consider as just one are actually two successive collisions. The player has an initial impact during a tackle but the brain receives trauma again when the head collides with the ground. Anderson says the double hit is generating more concussion impacts than a single hit.

For the freshmen players, Camarillo and his fellow researchers will be able to gather five years of data. He doesn't expect players at Stanford to have long-term damages if they just play at the collegiate level. But if brain problems begin to show up years down the road, the research team will have accurate records of the impacts they received playing college football.

The success of this study relies on a collaborative effort with a number of different departments at Stanford. Anderson says it's an unprecedented time of cooperation between the sports department, various research groups, and the players. Senior Fullback Ryan Hewitt says he's happy to be part of the study, even though he and his fellow players are “sort of the guinea pigs.” “I figure we might as well use someone,” he says, “and why not use us.” Hewitt hopes the data will help researchers figure out a little more about why concussions happen and eventually develop ways to prevent them.

Camarillo says it's going to take a long time to get any answers to those questions. Even with a big pool of data, he thinks it will be five to ten years before they can even begin to crack what causes concussions.