A standardized method for quantifying and characterizing repetitive head impacts in soccer matches using video footage.

Soccer athletes experience repetitive head impacts (RHI) through purposeful heading and unintentional head impacts, which may be associated with acute and chronic brain injury. Previous soccer studies have sought to quantify and characterize RHI, but to-date no consistent, standardized methods exist. The Heads-Up Checklist (HUC), originally used for characterizing head impacts in hockey, was modified to be used in soccer (soccer HUC [SHUC]). Our aim was to determine the reliability of quantifying ball-to-head impacts using video verification and to develop and test the reliability of the SHUC to characterize RHI in soccer. Two trained reviewers used the SHUC to quantify ball-to-head impacts and characterize non-ball-to-head impacts in 38 male and female collegiate soccer matches. Intraclass correlation coefficient (ICC) and Cohen's Kappa were used to assess interrater reliability. Independent