As you watch the Patriots and Giants smash into each other Sunday, consider this.

For two years researchers studied head impacts among 24 high school football players. They compared helmet-sensor data with brain imaging scans, along with cognitive tests. And they found that it’s not just a single blow to the head that causes concussion—it can also be the cumulative effect of multiple blows. The last impact is then the last straw for an already compromised brain. The research is in the Journal of Biomechanics.

Players received from 200 to nearly 1,900 hits to the head in one season, and sensors recorded impact forces of 20 to 100 Gs.

Of the players studied, six were officially concussed. But 17 more showed brain changes in areas associated with chronic traumatic encephalopathy, a degenerative disease known to affect concussed players. The brain scans also revealed that players relied on different strategies than did most people during cognitive tests, due to a reduction in their functional abilities.

Other studies have shown that once a player suffers a concussion, they are four times more likely to sustain a second one. But concussion or not, repeated blows to the head take their toll.  

—Christie Nicholson

[The above text is a transcript of this podcast,]