Background There is mounting evidence that dynamic neck strength may play a role in protecting against concussion. It is also well established that athletes with a prior history of concussion are at higher risk than those with no prior history.

Objective To assess if there is a difference in dynamic neck strength between athletes with a self-declared history of concussion (HxC) and athletes with no history of concussion (No-HxC). Secondly, to determine if dynamic neck strength can be used as a predictor for previous concussion history through a receiver operating characteristic curve (ROC) and hence, be used as a proxy for future concussion risk.

Design Observational cohort design

Setting Varsity level female competitive soccer players

Participants 28 athletes (average age 19.4 years, range 18–21), separated by self-declared history of concussion (HxC n=10 and No-HxC n=18)

Assessment Dynamic neck strength was calculated as the peak Rate of Force Development (RFD) in pounds-force per second (lb_f *s^-1) achieved during 50 revolutions on the TopSpin360 neuromuscular neck-training device.

Results RFD for HxC was 3.85 lb_f *s^-1 (95% CI 2.53 - 5.17 lb_f *s^-1) while RFD for No-HxC was 7.14 lb_f *s^-1 (95% CI 5.17 – 9.12 lb_f *s^-1) Independent samples t test p = 0.012. ROC cut-off value of 4.5 lb_f *s^-1 provides a sensitivity of 72% and specificity of 80% for detecting those with a history of concussion.

Conclusions In this pilot study of varsity female soccer athletes, those with a history of concussion demonstrate significantly lower dynamic neck strength measurements compared to teammates with no history of concussion. Knowing that HxC athletes are at higher risk of future concussion, the ROC cut-off value of 4.5 lb_f *s^-1 provides a starting point for future studies using dynamic neck strength values for assessing baseline concussion risk in athletes.