Relationship between Neck Musculature and Head Kinematics during a Collision in University American Football Players

OBJECTIVES Sport-related concussion (SRC) has been a focus of recent attention. Amongst American football players, it is often the result of high-energy collisions that cause the head to undergo high kinematics of linear acceleration (LA) and angular acceleration (AA). A player generally develops head and neck stiffness by contracting the neck muscles during a collision. Thus, the head kinematics experienced by a player during a collision may be related to the strength of these muscles.METHODS In a sample of 22 players from T University in the Kanto collegiate American football association second division, we measured neck strength, using a handheld dynamometer, Micro FET (Nihon Medix Co., Ltd.), and neck circumference, using a measure. We then measured their head kinematics (LA and AA) in collisions during seven competition games using an impact-sensing mouthguard. We performed Spearman’s rank correlation to assess the relationships between head kinematics, neck circumference, and neck strength.RESULTS A significant negative correlation between Top10%LA and neck flexor strength was observed during a collision. Additionally, significant negative correlations were observed between head kinematics and neck circumference.CONCLUSIONS Our main finding was that a stronger and thicker neck may reduce head kinematics during a collision. Although neck strength seems to be protective against SRC in collisions, further research is needed into the involvement of individual muscles and timing of muscle contraction. In our discussion, we emphasize the importance of neck strength training for minimizing SRC.