PROJECT SUMMARY Repetitive head impacts in contact sports are a significant public health concern due to their potential association with short- and long-term neurological deficits. There is debate amongst researchers as to the amount of exposure that may lead to neurocognitive changes; some researchers have demonstrated that these alterations could occur over the span of one season. Youth football players represent 70% of all athletes participating in the sport and experience over half of their head impacts during practice - an environment amendable to intervention. A current study (1K25HD101686-01A1) will develop an evidence-based intervention aimed to reduce head impact exposure in practices, using a community-engaged approach. This proposal enhances this parent study by incorporating clinical outcome assessments and engaging football athletes in the evaluation of the intervention program. The objective of this implementation-effectiveness study is to evaluate the effectiveness of the intervention program on reducing exposure in practices and its effect on mitigating changes in clinical outcomes, while monitoring the implementation process. In Aim 1, measures of neurocognition, postural control, and vestibular/ocular motor symptoms will be evaluated from athletes participating on control and intervention youth football teams as well as non-contact sports teams at pre- and post-season time points. Biomechanical data informing the frequency and severity of hits during the season will be measured using a custom instrumented mouthpiece. The effectiveness of the intervention at reducing head impact exposure and mitigating changes in clinical outcomes will be evaluated. In Aim 2, the feasibility and potential utility of the implementation strategy of the intervention program will be assessed to inform intervention program outcomes. Former youth football players participating at the high school and collegiate level will be engaged to evaluate the feasibility and acceptability of the intervention program. The results of this study will provide important pilot data on the effect of reducing exposure on clinical outcomes, while informing how the intervention program works and providing valuable insight into future large-scale testing of the intervention. The predoctoral Candidate will achieve the study aims through cross-disciplinary mentorship in injury biomechanics, public health, implementation science, neuropsychology, and sports medicine. This fellowship opportunity will also provide robust didactic training and experiential learning in traumatic brain injury, methods of biomechanical data collection and implementation science, biostatistics, clinical trials design, neurocognitive test administration and interpretation, and professional development. The research and training plan of this Predoctoral Fellowship will position the Candidate for success as a productive independent research scientist with a skillset to combine injury biomechanics and pu...