Browsing by Author "Young, Tyler James"

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    Head Impact Biomechanics and Helmet Performance in Youth Football
    Young, Tyler James (Virginia Tech, 2013-12-09)
    The research presented in this thesis aims to improve the knowledge of head impact biomechanics in youth football players by analyzing head impact exposure of youth football players and the performance of youth football helmets. The results of the studies presented provide a foundation for researchers, football leagues, and helmet manufactures to implement changes and modifications that aim to reduce concussion risk in youth athletes. The first study presented in this thesis aims to quantify the head impact exposure of 7 to 8 year old football players and determine the cause of variation in player exposure. To conduct this study, 19 players were instrumented with helmet mounted accelerometers that measured real-time acceleration data on the field. This data was analyzed to determine the magnitude, frequency, and location of each impact sustained by players in the 2011 and 2012 football season. From these data, it was determined that the average 7 to 8 year old player experienced 161 impacts per season, 60% of which were in practice and 40% were in games. The median impact for 7 to 8 year old players was 16 g and 686 rad/s². The magnitude of the 95th percentile impact was 38 g and 2052 rad/s². A total of 125 impacts above 40 g were recorded, 67% of which occurred in practices and 33% occurred in games. It was determined that returning players experienced significantly more impacts per season than first time players and practices had significantly higher magnitude impacts than games. These data can be used to further develop practice modifications that aim to reduce total impacts and high magnitude impacts experienced by youth football players. The second study presented in this thesis aims to quantify differences in youth football helmet performance before and after a football season. Currently, the only requirement regarding helmet recertification and reconditioning states that no helmet older than 10 years will be recertified or reconditioned. Quantitative data is needed to either support or refute this guideline and provide data describing how often youth football helmets should be recertified and reconditioned. To conduct this study, 6 youth Riddell Revolution football helmets, 3 that were new and 3 that had been used for one season, were tested on a drop tower from various heights and impact locations before and after the 2013 football season. It was determined that there was no significant difference in helmet performance before and after a season for new helmets or helmets that had been used for one season. In addition, there was no significant correlation between the frequency of impacts, the 95th percentile impact magnitude, or the product of the frequency and 95th percentile impact magnitude with the change in helmet performance. Future studies should be conducted that analyze the performance of youth football helmets over the course of multiple seasons.
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    Predicting Mild Traumatic Brain Injury with Injury Risk Functions
    Young, Tyler James (Brain Injuries and Biomechanics Symposium, 2013-09-19)
    To assess the safety of various products, equipment, and vehicles during traumatic events injury risk curves have been developed correlate measurable parameters with risk of injury. The first risk curves to predict head injuries focused on severe head injuries such as skull fractures. These curves were generated by impacting cadaver heads. To understand the biomechanics of mild traumatic brain injuries, cadaver heads have also been used to monitor pressure and strain in the brain during impacts. Live animal models have been used to understand the physiological response of the brain to impact to create thresholds for mild traumatic brain injuries such as concussions. These results have been scaled to humans. To generate injury risk curves from live human models, impacts from games in the NFL have been reconstructed in the laboratory. Helmets of NCAA football players have also be instrumented with accelerometers to collect all impacts during a season resulting in the development of injury risk curves that predict concussion as a function of both linear and rotational acceleration. These risk curves provide researchers with a better understanding of the efficacy of various safety systems and give insight as to how safety systems can be improved.