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. This is an improved method of capturing the cumulative effects from each impact because it accounts for nonlinear relationships between impact magnitude and the associated risk of injury, Stitzel said.
"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 median impact for each player ranged from 15.2 to 27.0 g, with an average value of 21.7 g, which shows the wide variability in the force of impacts.
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.
Additionally, the study found a wide variation in player exposure within the team, with a 22-fold variation in the exposure per impact for practices and a 47-fold variation in the exposure for impact for games.
Studies like this are vital to understanding the biomechanical basis of head injuries related to football, Stitzel said. The metric fully captures a
|Contact: Marguerite Beck|
Wake Forest Baptist Medical Center