Theses and Dissertations at Montana State University (MSU)
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Item Practicality and usability of high-density surface electromyography for lower limb prosthesis control(Montana State University - Bozeman, College of Engineering, 2022) Christensen, Fred Wallace; Chairperson, Graduate Committee: Corey PewSurface electromyography (sEMG) presents a pathway for prosthesis control but is prone to excess noise and signal corruption due to displacement. High Density Surface Electromyography (HDsEMG), which covers the same area as Traditional sEMG with multiple electrode channels as opposed to one channel, presents a way to overcome these challenges. Seven healthy participants were recruited and performed several activities of daily living with both Traditional sEMG and HDsEMG sensors on their Rectus Femoris, Biceps Femoris, Vastus Lateralis, and Semitendinosus muscles. These sensors were placed in both optimal locations over the muscle belly and in a location 1 cm distally from that optimal placement to simulate sensor displacement with use. From the data collected, four signals were created: a Traditional sEMG signal, the single HDsEMG signal with the highest signal-to-noise ratio (SNR) (Best Signal), a time mean of all HDsEMG signals (Composite Signal), and a time mean of all HDsEMG signals with SNR values greater than 2 dB (Threshold Signal). All signals' values for SNR, root-mean-squared means (RMS), DP ratio, and Omega ratio were compared in both optimal and displaced conditions. Phase lag and power domain similarity were used to assess response to displacement. Threshold mean and straight mean signals were identical in most values. The best signal displayed highest SNR, with the composite signal displaying second highest, and sEMG displaying lowest. These differences were more pronounced in extensor muscles in activities that involved large amounts of knee movements. sEMG signals displayed higher relative RMS values, as well as higher DP values. sEMG displayed statistically higher, but numerically similar Omega values. sEMG displayed a greater agreement between optimal and displaced signals in the frequency domain. Similarity was more dependent on activity type than signal type. Phase lag was determined to not be relevant. HDsEMG was proved to have potential for improved prosthesis control.Item Improving the understanding of cognitive- motor function and lower-extremity biomechanics(Montana State University - Bozeman, College of Engineering, 2021) Fischer, Patrick David; Chairperson, Graduate Committee: Scott Monfort; Keith A. Hutchison, James N. Becker, and Scott M. Monfort were co-authors of the article, 'Evaluating the spectrum of cognitive-motor relationships during dual-task jump landing' in the journal 'Journal of applied biomechanics' which is contained within this dissertation.; Keith A. Hutchison, James N. Becker and Scott M. Monfort were co-authors of the article, 'Do dual-task demands generalize across sport-specific movements?' submitted to the journal 'Journal of applied biomechanics' which is contained within this dissertation.; Keith A. Hutchison, James N. Becker and Scott M. Monfort were co-authors of the article, 'Decoupling visual constraint from rapid decision-making effects during a jump-landing' submitted to the journal 'American journal of sports medicine' which is contained within this dissertation.Anterior cruciate ligament injuries present a considerable problem for athletic populations, especially those that engage in sports with open-skill movement demands like rapid changes of direction. These injuries typically occur in a non-contact setting, that is, the forces generated by the athlete's own movement overburden the ligaments in the knee and cause partial or total rupture of the tissue. Considerable effort has been devoted to researching and, by extension, counteracting the physical contributions to injury risk; for example, athletes are encouraged to develop better balance and lower-extremity strength to counteract the adverse effects of poor movement performance. However, anterior cruciate ligament injury risk is also tied to cognitive factors as well as physiological factors. This athlete-specific cognitive-motor relationship interacts with external distractions in the sporting environment to compromise an athlete's ability to move safely and effectively. The purpose of this research was to investigate contributions of different cognitive domains to movement performance in distracted, sport-relevant scenarios, to develop a better understanding of the cognitive-motor relationships that underpin injury rates in these athletic populations. A series of studies involving biomechanical and cognitive outcome measures demonstrated that cognitive function has an important, if not fully understood, role to play in mitigating an athlete's susceptibility to distractions during open-skill movement performance. This research adds to a critically underdeveloped body of work explaining the subject-specificity of dual-task movement performance in a lab setting and provides a foundation for developing new injury risk assessment and mitigation efforts for clinicians and coaches.Item An analytical model of the patello-femoral joint(Montana State University - Bozeman, College of Engineering, 1978) Hagelin, Jack Stephen