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Harrison, Layci
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Middle Tennessee State University
Functional movement assessments are used to predict injury in multiple populations, but the components that most contribute to functional movement are unknown. Identifying the influence of static balance via the Balance Error Scoring System (BESS) and dynamic balance via the Y-Balance Test (YBT), can provide valuable information to clinicians. This information can be used to help individuals improve functional movement screening (FMS) scores which, in turn, can reduce injury risk. After injury, some individuals experience anterior balance asymmetry, which further increases injury risk. However, early balance training on a limb during rehabilitation is often contraindicated. The cross-over effect, which occurs when training benefits are observed in an untrained limb following training of the contralateral limb, may be helpful in minimizing the development of balance asymmetries following injury. In study one of the dissertation, the contributions of static and dynamic balance on functional movement were evaluated and the contributions of BESS and YBT scores to FMS scores were determined. The effects of unilateral balance training on bilateral anterior reach in those with a bilateral asymmetry in anterior reach was tested in the second study. In the first study, participants from the general population (N = 71) completed the FMS, the YBT, and the BESS. Together (p < .001, R2 = .54) and individually, both YBT (p < .001, R2 = .498) and BESS (p < .001, R2 = .321) were significant predictors of FMS scores. When controlling for age (p < .001, R2 Change = .364) and history of lower body surgery (p < .001, R2 Change = .532), the YBT and the BESS were still significant predictors of the FMS. Risk of injury according to YBT risk and FMS risk were not associated, χ^2 (1,N=77)=1.20, p = .273, Cramer’s V = .125. There was a significant association between BESS risk and FMS risk, χ^2 (1,N=77)=9.27, p = .01, Cramer’s V = .347. In the second study, a subgroup from the first study (N = 16) with an anterior reach asymmetry completed 5 weeks of balance training on the leg with the better balance according to the YBT. After 5 weeks of balance training, there was not a significant interaction between group and time for the trained leg (G-G p = .594, n2p = .035) indicating the training was not effective at improving anterior reach of the trained leg. There was also not a significant interaction between group and time for the untrained leg (G-G p = .403, n2p = .028), showing no cross-over of balance ability to the untrained leg. Overall, static and dynamic balance both contribute to functional movement. This information can be used when developing training and rehabilitation protocols to reduce injury risk as measured by FMS. However, the training outlined in this study did not significantly improve anterior reach of the trained or untrained leg in individuals with an anterior reach asymmetry. As a result, more research in needed to identify a training protocol to improve anterior reach and, therefore, reduce injury risk in this population.