Thesis (Ed.D.)--Georgia Southern University, 2009. / "A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Directed by Thomas Buckley. ETD. Includes bibliographical references (p. 27-30) and appendices.

Thesis (Ed.D.)--Georgia Southern University, 2009. / "A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Directed by Barry Munkasy. ETD. Includes bibliographical references (p. 59-61) and appendices.

Thesis (M.S.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains vi, 93 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (M.A.)--University of North Carolina at Chapel Hill, 2004. / Includes bibliographical references (leaves 119-123). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.S.)--Georgia Southern University, 2006. / "A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science" ETD. Includes bibliographical references (p. 62-65) and appendices.

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains vii, 85 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (M.A.)--University of North Carolina at Chapel Hill, 2004. / Includes bibliographical references (leaves 119-123).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 87 p. : col. ill. Includes abstract. Includes bibliographical references.

Lower extremity powered exoskeletons (LEPE) allow people with spinal cord injury (SCI) to perform activities of daily living, such as standing, walking, or stair and ramp ascent/descent. However, current LEPE walk slowly and require extensive use of forearm crutches to maintain user stability. Consequently, this limits LEPE time of use and overall system performance. While the biological ankle is known to be critical for energy efficiency, speed, and stability in able-bodied walking, current LEPE do not include biomimetic ankle designs and thus limit device performance. The objective of this thesis is to determine biomimetic ankle mechanics for a LEPE, thereby defining ankle design requirements that could reduce crutch loads and thus extend LEPE use. Virtual prototyping techniques were used to achieve this objective. Two 3D models of a real LEPE (ARKE, Bionik Laboratories) attached to a human musculoskeletal model were developed and validated. The first model (biomimetic model) was driven by 3D marker kinematics from 30 able-bodied participants walking at four realistically slow LEPE walking speeds. The second model (SCI model) was driven by 3D marker kinematics from five SCI participants walking in the ARKE LEPE with instrumented forearm crutches. Once the models were validated by comparing predicted to measured ground reaction forces (GRF) and centre of pressure (COP) trajectories, biomimetic LEPE ankle design requirements were determined. Ankle range of motion, quasi-stiffness, work, peak moment, and peak power were compared between human and human+ARKE models, across four gait phases and four slow walking speeds. The major findings were: the human+ARKE model had significantly different quasi-stiffness values across all four gait phases; quasi-stiffness increased with increasing speed; the human+ARKE model’s ankle always absorbed net-work, even at the fastest walking speed; quadratic regression was significantly more accurate than linear regression for modelling ankle quasi-stiffness. These results suggested that passive variable stiffness ankles incorporating quadratic elastic spring elements could achieve biomimetic ankle functions and thus potentially increase LEPE user walking speed, stability, and reduce overuse of crutches.

The original purpose of this investigation was to determine if soccer players who performed an agility training program in a specialized training shoe would have a lower incidence of acute ankle sprains as compared to controls. Two elite male college soccer teams participated in the study. The experimental team performed an agility training program two to three days per week over a three month period wearing the Nike Free Trainer. Data on ankle sprain incidence throughout the season was collected, as well as scores on tests of ankle strength, static balance, dynamic balance, agility and self-reports of ankle function. These scores were compared to those of the control team. Statistical analysis showed a statistically significant improvement in the experimental team members in the anteromedial reach direction of the dynamic balance test (p=0.001). This group also showed positive trends in ankle strength ratio and five of the eight other reach directions of the dynamic balance test. Unfortunately, pre-test, post-test statistical analysis was possible for only half of the experimental team subjects. Post-test data was not generated for the other half of these subjects due to unrelated injury or subject noncompliance. Lack of pre-test data due to subject non-compliance in the control team hindered between group statistical comparisons. This study uncovered promising trends as to the potential for gains in dynamic balance as a result of agility training with Nike Free Trainer. This study also established the reliability of three clinical tests of ankle strength, static balance and dynamic balance. Future well-designed studies are recommended to research this area further to discern the effect of this agility training program on dynamic balance and establish its’ effect on ankle sprain incidence. / Education, Faculty of / Kinesiology, School of / Graduate