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Context: During thoroughbred races, jockeys are placed in potentially injurious situations, often with inadequate safety equipment. Jockeys frequently sustain head injuries; therefore, it is important that they wear appropriately certified helmets. Objective: The goals of this study are (1) to perform impact attenuation testing according to ASTM F1163-15 on a sample of equestrian helmets commonly used by jockeys in the United States and (2) to quantify headform acceleration and residual crush after repeat impacts at the same location. ParticipantsandDesign: Seven helmet models underwent impact attenuation testing according to ASTM F1163-15. A second sample of each helmet model underwent repeat impacts at the crown location for a total of 4 impacts. Setting: Laboratory. Intervention: Each helmet was impacted against a flat and equestrian hazard anvil. MainOutcome Measures: Headform acceleration was recorded during all impact and computed tomography scans were performed preimpact and after impacts 1 and 4 on the crown to quantify liner thickness. Results: Four helmets had 1 impact that exceeded the limit of 300g. During the repeated crown impacts, acceleration remained below 300g for the first and second impacts for all helmets, while only one helmet remained below 300g for all impacts. Foam liner thickness was reduced between 5% and 39% after the first crown impact and between 33% and 70% after the fourth crown impact. Conclusions: All riders should wear a certified helmet and replace it after sustaining a head impact. Following an impact, expanded polystyrene liners compress, and their ability to attenuate head acceleration during subsequent impacts to the same location is reduced. Replacing an impacted helmet may reduce a rider’s head injury risk.

Mattacola is with Academic and Faculty Affairs, Jockey & Equestrian Initiative, Sports Medicine Research Institute, College of Health Sciences, University of Kentucky, Lexington, KY. Quintana is with the Rehabilitation Sciences Doctoral Program, Jockey & Equestrian Initiative, Sports Medicine Research Institute, College of Health Sciences, University of Kentucky, Lexington, KY. Crots is with the Division of Athletic Training, Department of Rehabilitation Sciences, College of Health Sciences, University of Kentucky, Lexington, KY. Tumlin is with Occupational and Environmental Health, Jockey & Equestrian Initiative, Sports Medicine Research Institute, College of Public Health, University of Kentucky, Lexington, KY. Bonin is with MEA Forensic Engineers & Scientists, Laguna Hills, CA.

Mattacola (carlmat@uky.edu) is corresponding author.
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