Scientists at an US academic medical centre have developed a new way to measure the cumulative effect of impacts to the head incurred by football players.
According to Joel Stitzel from the Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences under the Wake Forest Baptist Medical Center, the metric, called Risk Weighted Cumulative Exposure (RWE), can capture players' exposure to the risk of concussion over the course of a football season by measuring the frequency and magnitude of all impacts.
Based on data gathered throughout a season of high school football games and practices, the researchers used RWE to measure the cumulative risk of injury due to linear and rotational acceleration separately, as well as the combined probability of injury associated with both.
Concussion is the most common sports-related head injury, with football players having the highest rate among high school athletes, according to the study. It is estimated that nearly 1.1 million students play high school football in the United States.
With such a large number of players in the sport, it is critical to understand the risk associated with different levels of impact and accurately estimate cumulative concussion risk over the course of a practice, game, season or lifetime, Stitzel said.
In the Wake Forest Baptist study, the researchers measured the head impact exposure in 40 high school football players by using sensors placed in their helmets to record linear and rotational acceleration. A total of 16,502 impacts were collected over the course of one football season and the data were analyzed as a group and as individual players.
Impacts were weighted according to the associated risk from linear acceleration and rotational acceleration alone, as well as to the combined probability of injury associated with both.
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"All hits involve both linear and rotational acceleration, but rotation coveys 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," Stitzel said.
The study found that impact frequency was greater during games (15.5) than during practices (9.4). However, overall exposure over the course of the season was greater during practices.
This information may help teams reduce exposure to head impacts during practices by teaching proper tackling techniques that could reduce exposure to impacts that may result in a higher concussion rate, the researchers reported.