With concussions accounting for the majority of football-related injuries, researchers have been trying to make advances in preventative technologies. Now, researchers have developed a better way to assess how exposed players are to concussions over the course of a football season, and they believe it can lead to improved techniques for tackling.

Using a metric called Risk Weighted Cumulative Exposure (RWE), players' exposure to the risk of concussion could be measured by the frequency of linear and rotational impacts over the course of a high school football season.

"All hits involve both linear and rotational acceleration, but rotation conveys the idea that your head is pivoting about the neck whereas linear acceleration is experienced from a direct blow in more of a straight line through the center of mass of the head," Dr. Joel Stitzel, chair of biological engineering at Wake Forest Baptist Medical Center, said in a statement.

It's important to understand the different levels of risk associated with different levels of impact in order to accurately determine cumulative concussion risk, Stitzel said. This applies to tackles incurred over the course of a player's football career.

To find out how exposed these players were to concussions over the course of a season, Stitzel and his team counted the number of impacts in 40 high school football players by using sensors placed inside of the helmets.

A total of 16,502 impacts were counted, and examined separately for the associated risk of linear and rotational acceleration, as well as the combined probability of injury. The median impact for each player ranged from 15.2 to 27 g, while the average was 21.7 g. Stitzel said this shows the wide variability in the force of impacts.

They also found that average impacts happened more often during games, with 15.5 impacts, compared to 9.4 impacts during practice. But overall exposure during the course of the season occurred more during practice.

"This measure gives us a way to look at a large number of players and the hits they've incurred while playing football," Stizel said. "We know that young players are constantly experiencing low-level hits that don't cause visible injury, but there hasn't been a good way to measure the associated risk of concussion."

Scientists at the University of Nebraska's Center for Brain, Biology, and Behavior (CB3) recently developed a technology that may also help determine the severity of a concussion. An electrode covered mesh cap can be placed over a player's head after a particularly heavy impact, and determine the severity of the impact based on the player's reaction to stimuli.

"We can get an idea of what area of the brain is being involved in the process, whether the speed of processing is at the rate it should be," Dennis Molfese, of the National Academy of Sciences Institute of Medicine Committee, said. "The different areas of the brain that normally integrate information quickly stop doing that, so that's another way we should be able to pick up whether there is an injury or not."

Concussions are a big issue, not only for football, but for many other sports. A recent study concluded that there wasn't enough being done to teach youth football players how to tackle correctly, and that because of this, many of them were incurring more concussions during games than during practice.

Professional football players saw new kickoff rules — moving the kickoff line up five yards — during the 2010-11 season, reducing the number of concussions by 43 percent.

"There are a lot of things that are very important with the N.C.A.A. as far as the health and safety of the student-athlete," Brian Hainline, another researcher with CB3, said, "and concussion is right up there as first and foremost. It's the elephant on the table, and we, with everyone else, we have to solve it."


Urban J, Davenport E, Stitzel J, et al. Head Impact Exposure in Youth Football: High School Ages 14 to 18 Years and Cumulative Impact Analysis. Annals of Biomedical Engineering. 2013.