Imagine that a high school football player takes a hard hit during a game. He seems a little shaken up, and he's a little little wobbly as he leaves the field, but five minutes later he swears he’s fine and wants to be put back in the game. But if he’s had a concussion, he’s not supposed to return to play. What tools does the coach or trainer have to try to determine whether he’s okay to play or not? After all, not all hard hits result in concussions; he’s probably just fine….
A common finding after a concussion is that the person’s physical reaction time decreases. But how can one measure a decreased reaction time quickly and accurately on the sideline? Researchers at The University of Michigan developed and validated a simple technique - here’s how it works. The athlete rests his forearm comfortably on a table with his opened hand extended just off the front edge of the table. A trainer or coach holds a measuring rod such as a yardstick by its upper end, positioning the lower end at the athlete’s hand level. When he lets go of the stick, the athlete grabs it. Where the athlete grabs the measuring rod (the number of inches that the rod falls before he grasps it) is an indirect measure of reaction time. If measurements of reaction time are made on every athlete before the season begins, slower reaction times can be determined easily and quickly any time a concussion is suspected.
Of course, the method only actually measures the distance the rod falls before the athlete grasps it, so it’s not a true measure of reaction time. But that doesn’t matter; if the rod falls more than usual before the athlete grasps it, his reaction time is slower and he should be evaluated by a medical professional before he is allowed to play again.
For those who are interested, the method is described in a publication in the Brit. J. of Sports Medicine.