Research Reports - Concussion Testing Should Not Overlook Physiology

With the ice hockey and football seasons now in full swing, kinesiology experts are examining the prolonged effects of concussions on athletes. While many athletes think they are recovered and asymptomatic two days after a concussion, research published by the American College of Sports Medicine suggests the physiological aftermath of a concussion may actually linger for three to seven days.

The research team led by J. Patrick Neary, Ph.D., compared cerebrovascular reactivity in post-concussion brains and healthy brains by measuring blood flow in their middle cerebral artery. The blood flow rate and carbon dioxide levels of 31 athletes (10 who had suffered a concussion within seven days prior to testing and 21 who were concussion-free for at least two months) were monitored at baseline, while breath-holding, while hyperventilating and at recovery.

Healthy and concussed athletes at rest had similar results for blood flow rate and carbon dioxide levels. However, concussed athletes and healthy athletes differed under the physiological stress of breath-holding and hyperventilation. While healthy athletes’ brains recovered quickly from holding their breath and hyperventilating, concussed athletes’ brains failed to return to resting levels.

These findings support the revised team physician consensus statement on concussion released last month by the American College of Sports Medicine. The revision stated that while neuropsychological testing is one component of the concussion evaluation process, it should not be used as a stand-alone tool to diagnose or manage concussions or to make return-to-play decisions.

“This provides further support that a physiologically challenging protocol, like the one devised here, is needed to confirm whether athletes are fully recovered from a concussion and able to return to play,” said Neary.

Concussions can cause short- and long-term complications that affect an athlete’s cognitive and emotional abilities. While the findings are promising, more research is needed on the pathophysiology of concussion to draw firm conclusions.

The study, “Cerebrovascular Reactivity Impairment after Sport-Induced Concussion,” is published in this month’s issue of Medicine & Science in Sports & Exercise®, the official journal of ACSM.

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 45,000 international, national and regional members and certified professionals are dedicated to advancing and integrating scientific research to provide educational and practical applications of exercise science and sports medicine.

“Suffering a concussion may actually impair the brain’s ability to recover after routine physiological stress,” said Neary, a researcher with the University of Regina in Regina, Saskatchewan, Canada. “Throughout the testing protocol, concussed athletes had cerebrovascular abnormalities not seen in healthy athletes.”

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