[JESSIE OLDHAM] Concussion exposure 
- a lot of people
think that football, simply because it
does have the highest number of
participants, is the highest exposure rate.
But actually if you look at collegiate
athletes, football is fourth behind
wrestling and men's and women's ice hockey.
[MELISSA DiFABIO] In this study, we're trying to
look at not necessarily concussions, but
the role of repetitive head impacts.
So not every time that you're going to
sustain an impact to the head, it will end
up being enough of a force that causes
a concussion.
We are trying to see what, if anything,
changes over the course of a competitive
ice hockey season, which is a collision sport
where they take many hits to the head,
not all of which are concussive.
[KATIE BREEDLOVE] Before the hockey season 
started, players came
in and did some clinical baseline
testing. We also did something in the gait
lab where they were walking, looking at
how they walked over time, how they
started walking, ended walking and their balance.
[JESSIE] Even if they don't suffer a
concussion,
are they still affected? Is their gait
still affected by the number of
sub-concussive hits that they take over
the course of the season?
[KATIE] Then we also did some baseline 
Magnetic Resonance Imaging.
Then we have the players wear
helmet telemetry devices - those little
sensors that go underneath their helme,
that they wear during practices and home
games, and we measure how many impacts,
where the impacts occur and how many
g-forces - or just basically how hard
they're getting hit.
[MELISSA] So if you really think about the way that a concussion
can occur, especially in ice hockey, it
has a lot to do with how well
they're able to brace their neck.
If they're able to contract that cervical
musculature, if they can see someone coming at
them or they know they're about to
skate into the boards, they have a sense
that someone's going to hit, them they can
brace up a little bit like this so their
head doesn't move back and forth as much.
So it's really those unseen hits or
someone's coming at them from behind or
their head is down, and that's the mechanism
that you really worry about.
