Frequency & Magnitude of Helmet Impacts in One Season of Collegiate Football: An Investigation Into the Effect of Session and Position Type

Abstract

Background: Concussive and subconcussive head impacts play important roles in long-term brain health. Professional and collegiate football leagues have been taking steps to reduce dangerous and injurious hits during games, and a select few leagues have eliminated contact practices to improve player safety. It has been hypothesized that training camp presents a unique set of circumstances for players, in which they are competing at a high level of intensity and are vying for a spot on their team, and are participating in more than one practice per day. However, there has been no research conducted to date that has measured head impacts sustained in training camp. To this end, we explored the relative exposure of helmet impacts during football games, practices, and training camp, and how impact tally and magnitude differ between session types. We also explored the relative exposure of helmet impacts and magnitudes between position types. Methods: Helmet mounted accelerometers were used to record impacts sustained by collegiate football players through training camp, practices and games for one season. Linear acceleration, rotational velocity, and impact location were recorded for every impact. Impacts were analyzed to determine differences in impact tallies and impact magnitudes for different session types and position types. Players were classified as inside or outside of the box. Players that line up in close proximity to the ball, roughly within 3-5 yards of the line of scrimmage, are considered to be inside the box. Players that begin each play at a distance from the ball or further than five yards from the line of scrimmage are considered to be outside of the box. Results and Discussion: Impacts occurred at the highest frequency and linear acceleration in games, followed by training camp, then practices. Impacts occurred at the highest rotational velocity in games, followed by practices, with no difference between practices and training camp. Players inside of the box sustained impacts at a higher frequency and magnitude than players outside of the box. Based on our findings, training camp may pose a greater risk to player safety than practices, especially for players inside of the box.