A test has been developed to determine whether concussed athletes are fit to compete again. © Jan Milne
However, the test relies on competitors performing a yardstick test first to get their reaction time on record.
Concussion is a common injury in riders in falls, with strict rules in some jurisdictions over the return of riders to competition, including mandatory stand-downs.
A study released this week, to be presented at the American Academy of Neurology's annual meeting in Canada in April, relies on the slower reaction time in concussed athletes to indicate concussion.
"Research has shown that reaction time is slower after a concussion - even as long as several days after other symptoms are gone," said study author James Eckner, of the University of Michigan Department of Physical Medicine and Rehabilitation in Ann Arbor.
"But the tests currently used to measure reaction time require computers and special software."
Eckner and his colleagues developed a simple, inexpensive device to measure reaction time: a cylinder attached to a weighted disk. The examiner releases the device and the athlete catches it as soon as possible.
For the study, the researchers gave the test to 209 Division One college football, wrestling and women's soccer athletes during their pre-season physicals.
Then, any athlete who had a concussion diagnosed by a physician during the season took the test again within three days of the concussion.
Eight athletes had concussions during the study. Of those, seven of the athletes had a prolonged reaction time after the concussion compared to the pre-season time. Catching the object took about 15 percent longer.
"Because of its simplicity and low cost, this test may work well with youth athletes, where there is limited access to computerised testing of reaction time," Eckner said.