Hot on the heels of the Super Bowl, comes new research from the University of Michigan, Ann Arbor, on concussions and head hits in football players and how the head reacts to impacts. Using crash test dummies wearing helmets and a laboratory drop tower, the researchers approximated the force of two linemen colliding at the start of a play.

How hard was the hit? Where was it centered? And what reactions did it cause in the defensive dummy head? Sensors sent the answers to a laptop across the room.

Although it will take weeks for the researchers to analyze the data from several days of drops, they say this information is especially needed as the sports and science communities become more aware of the long-term effects that decades' worth of concussions and head hits can have on players.

Chronic traumatic encephalopathy, a progressive and degenerative disease that involves early-onset dementia, depression and trouble controlling impulses, has been found in the autopsied brains of more than 50 former NFL players.

This experiment won't immediately address the question of why some exhibit symptoms down the road and others don't, but the researchers are comparing two high-profile head-impact monitoring systems—Riddell's Head Impact Telemetry System (HITS) and the newer X2 Biosystems' X-Patch.

HITS studs a football helmet with a handful of accelerometers that measure motion in a straight line. It can say where a blow falls and measure how fast the head accelerates as a collision pushes and twists it. It gets at the twist indirectly with an algorithm that uses the accelerometer data.

X-Patch is a fingertip-sized device worn behind the ear. It also uses accelerometers to measure linear motion, but tracks rotation speed more directly with a gyroscope similar to the ones that help iPhones calculate their orientations. In recent years, researchers have come to suspect that head rotation may play an important role in concussions and so this direct measurement could prove valuable.