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Tuesday, August 26, 2014

Are Athletes Playing Too Soon After a Concussion?

From the University of Oregon
via Futurity

August 21, 2014

High school athletes who return to the field less than a month after a concussion may have trouble walking and performing mental exercises at the same time, a new study shows.

Researchers tested 19 athletes and found that 12 showed signs of regression in balance and/or speed. Seven who didn’t return for more than 20 days performed similarly to uninjured control subjects.

The findings, published online ahead of print in Medicine & Science in Sports & Exercise, take a closer look at data from a 2013 study in the same journal.

That study showed that 25 concussed high school athletes had compromised abilities to focus and switch tasks for up to two months after their injuries. Six of the athletes did not return to action in the study period and were excluded in the new analysis.

In the course of the original research, athletes reported on when they had been cleared to resume practicing. At 28 days post injury, the data suggested a regression, says principal investigator Li-Shan Chou, professor of human physiology at University of Oregon.

“We had seen this same type of curve in an earlier study of college athletes,” he says. “We didn’t have any evidence linking it to a return to activity, but we did discuss that possibility, because we knew that they usually were permitted to return to practice two weeks after a concussion.”

"For many of us, that is just a blink of the eyes, but for athletes
to be sure their bodily position is ready to perform a very skillful
avoidance maneuver or prepare to safely take a collision,
30 milliseconds is a critical length of time for assuming
that posture," says Li-Shan Chou.

A Turn in Recovery

For the new analysis, lead author David Howell, looked at when the athletes—13 from football, four from soccer, and one each from wrestling and volleyball—returned to activity.

He focused on individual data, comparing return-to-activity status with the results of three tests: simply walking, separately doing simple computerized mental exercises, and a combination in which they walked and performed mental exercises simultaneously.

“There had been a continuous improvement prior to the athletes’ return to activity,” Chou says. “But at the data point taken after their return to activity, we saw a turn in their recovery in the opposite direction.

“When the athletes did a simple walking test, there was no regression. Just using the computer task to probe their cognitive functioning, we didn’t see a regression. However, put together, we did.”

Slower Reaction Time

In the dual task exercise, the athletes, while walking, heard a spoken word and identified whether it was delivered in a low- or high-pitched tone. In other variations, the subjects’ were told, as they began walking, to recite months backward from October or subtract 7 repeatedly, beginning from 100.

The more complex a secondary task the greater the effect on a concussed individual than a non-injured control subject, Chou says.

The earlier published study found slowed reaction time of 30 to 40 milliseconds among concussed athletes two months after injury.

“For many of us, that is just a blink of the eyes, but for athletes to be sure their bodily position is ready to perform a very skillful avoidance maneuver or prepare to safely take a collision, 30 milliseconds is a critical length of time for assuming that posture,” he says.

Control subjects were healthy individuals of the same sex, body size, age, and sport of the injured athletes. The research focused on frontal regions of the brain responsible for working, or short-term, memory and executive function.

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