



NFL players risk their health every time they play a game - especially if it’s cold outside. New research shows that the risk of concussion doubles for NFL athletes when they play in 50-degree or less weather. The risk of getting an ankle injury also increases by 1.5 times in colder temperatures.

"There has been a lot of discussion recently about the significant risk of injury in the NFL and general player safety," said lead study author David Lawrence, a clinical fellow at St. Michael's Hospital. An emphasis has been placed on preventing concussions because they lead to severe long-term health problems, such as chronic traumatic encephalopathy (CTE).

CTE is a progressive degenerative disease that affects the brain. The symptoms usually begin to show about 8 to 10 years after experiencing repetitive blows to the head. The first stage of symptoms includes disorientation and headaches. The second stage includes symptoms such as memory loss, erratic behavior, and poor judgment. By the time the patients are within the third and fourth stages of the disorder, they experience severe symptoms, such as vertigo, deafness, progressive dementia, tremors, and suicidal ideation.NFL players are three times more likely to get an injury than a professional rugby player and 25 times more likely to get an injury than an NHL player. Their risk of concussion is three times higher than a rugby player and five times higher than an NHL player.The first step to lowering the risk of injury is to identify what affects the injury rates. With this in mind, the researchers looked at risk factors associated with the most common NFL injuries. They took the weekly injury report data from two regular seasons between 2012 and 2014 for all 32 NFL teams. The five most frequent injuries, in order from first to fifth, were knee-related injuries, ankle, hamstring, shoulder, and concussions. The researchers checked to see if and how external influences related to the injuries. The external factors included playing surface, climate factors, travel times, and game outcomes.The cold weather was not the only external factor that affected injury rates. The rate of shoulder injury was 1.36 times higher when games were played on natural grass as opposed to synthetic turf."There is limited research looking at the external risk factors for injuries in the NFL," said Lawrence. "Given this is one of the first studies to look at these variables, we can only speculate... on the underlying causes for the associations we observed with specific injuries on game days."For instance, one underlying cause could be that equipment and materials have lower elasticity at colder temperatures. The elasticity usually absorbs some impact of a blow. Another factor to consider is that, during hotter weather, athletes could mistake a concussion for a heat-related issue."Our findings contribute to the growing body of evidence surrounding this topic, but further research is needed," Lawrence said. "Applying this information may help inform future injury prevention strategies in the NFL, or other professional sports, and highlight the effects of these seemingly small external factors.”The research was published on March 31 in the Orthopedic Journal of Sports Medicine Sources: St. Michael’s Hospital press release via EurekAlert! Alzheimer’s Association via alz.org , Medicine Billing & Coding (Infographic)