Introduction: Claims that foot orthoses can resolve low-back pain are common in the marketing of these devices. The claims are based on the notion that wearing the orthoses will limit excess pronation at the subtalar joint thus reducing excessive internal tibial and femoral rotations. Excess leg rotations increase the anterior tilt of the pelvis and subsequently the degree of lumbar lordosis. Since lumbar lordosis has been suggested as a cause of low-back pain, it is speculated that foot orthoses could be used to treat and prevent pain to the low-back by reducing the forward curvature of the spine. This mechanical link between foot function and the low-back has not been investigated by experimental studies. Purpose: The purpose of this thesis was to investigate whether increased internal rotation of the femur induced an anterior tilt of the pelvis thus increasing the degree of lumbar lordosis and if external rotation induced a posterior pelvic tilt thus decreasing the degree of lumbar lordosis. Methods: In order to internally and externally rotate the femur, participants placed their feet in 18 different foot positions. Seven of these positions ranged from 15 degrees of foot eversion to 15 degrees of foot inversion and 11 positions ranged from 40 degrees of external foot rotation to 40 degrees of internal foot rotation. Six cameras surrounded the motion capture area and angles of pelvic tilt and lumbar lordosis were calculated. Results: Foot eversion and inversion did not have a statistically significant effect on pelvic tilt and lumbar lordosis. In-toeing had a statistically significant linear relationship with anterior pelvic tilt (R2=0.35, F1,131=69.79, p=0.00). Internally and externally rotating the feet had no effect on lumbar lordosis (R2=0.001, F1,153=0.09, p=0.77). Conclusion: Internally rotating the legs caused the pelvis to tilt anteriorly but only at extreme ranges of motion, much greater than what would normally be seen during gait. At which point, lumbar angles remained unaffected. This study does not dispute the effectiveness of foot orthoses to treat low-back pain but the results do not support the mechanical link proposed as the mechanism by which they work.

Introduction: Claims that foot orthoses can resolve low-back pain are common in the marketing of these devices. The claims are based on the notion that wearing the orthoses will limit excess pronation at the subtalar joint thus reducing excessive internal tibial and femoral rotations. Excess leg rotations increase the anterior tilt of the pelvis and subsequently the degree of lumbar lordosis. Since lumbar lordosis has been suggested as a cause of low-back pain, it is speculated that foot orthoses could be used to treat and prevent pain to the low-back by reducing the forward curvature of the spine. This mechanical link between foot function and the low-back has not been investigated by experimental studies. Purpose: The purpose of this thesis was to investigate whether increased internal rotation of the femur induced an anterior tilt of the pelvis thus increasing the degree of lumbar lordosis and if external rotation induced a posterior pelvic tilt thus decreasing the degree of lumbar lordosis. Methods: In order to internally and externally rotate the femur, participants placed their feet in 18 different foot positions. Seven of these positions ranged from 15 degrees of foot eversion to 15 degrees of foot inversion and 11 positions ranged from 40 degrees of external foot rotation to 40 degrees of internal foot rotation. Six cameras surrounded the motion capture area and angles of pelvic tilt and lumbar lordosis were calculated. Results: Foot eversion and inversion did not have a statistically significant effect on pelvic tilt and lumbar lordosis. In-toeing had a statistically significant linear relationship with anterior pelvic tilt (R2=0.35, F1,131=69.79, p=0.00). Internally and externally rotating the feet had no effect on lumbar lordosis (R2=0.001, F1,153=0.09, p=0.77). Conclusion: Internally rotating the legs caused the pelvis to tilt anteriorly but only at extreme ranges of motion, much greater than what would normally be seen during gait. At which point, lumbar angles remained unaffected. This study does not dispute the effectiveness of foot orthoses to treat low-back pain but the results do not support the mechanical link proposed as the mechanism by which they work.

Introduction: Claims that foot orthoses can resolve low-back pain are common in the marketing of these devices. The claims are based on the notion that wearing the orthoses will limit excess pronation at the subtalar joint thus reducing excessive internal tibial and femoral rotations. Excess leg rotations increase the anterior tilt of the pelvis and subsequently the degree of lumbar lordosis. Since lumbar lordosis has been suggested as a cause of low-back pain, it is speculated that foot orthoses could be used to treat and prevent pain to the low-back by reducing the forward curvature of the spine. This mechanical link between foot function and the low-back has not been investigated by experimental studies. Purpose: The purpose of this thesis was to investigate whether increased internal rotation of the femur induced an anterior tilt of the pelvis thus increasing the degree of lumbar lordosis and if external rotation induced a posterior pelvic tilt thus decreasing the degree of lumbar lordosis. Methods: In order to internally and externally rotate the femur, participants placed their feet in 18 different foot positions. Seven of these positions ranged from 15 degrees of foot eversion to 15 degrees of foot inversion and 11 positions ranged from 40 degrees of external foot rotation to 40 degrees of internal foot rotation. Six cameras surrounded the motion capture area and angles of pelvic tilt and lumbar lordosis were calculated. Results: Foot eversion and inversion did not have a statistically significant effect on pelvic tilt and lumbar lordosis. In-toeing had a statistically significant linear relationship with anterior pelvic tilt (R2=0.35, F1,131=69.79, p=0.00). Internally and externally rotating the feet had no effect on lumbar lordosis (R2=0.001, F1,153=0.09, p=0.77). Conclusion: Internally rotating the legs caused the pelvis to tilt anteriorly but only at extreme ranges of motion, much greater than what would normally be seen during gait. At which point, lumbar angles remained unaffected. This study does not dispute the effectiveness of foot orthoses to treat low-back pain but the results do not support the mechanical link proposed as the mechanism by which they work. / Education, Faculty of / Kinesiology, School of / Graduate

Athletes competing in the unarmed combat sport of mixed martial arts (MMA) are at an increased risk for long-term neurological consequences due to repetitive head trauma. Mass differentials as well as reported differences in fight styles between Lightweight and Heavyweight fighters in MMA may affect head impact kinematics creating different levels of head injury risk. Factors that influence the risk for head injury include the frequency, magnitude and interval of head impacts. The purpose of this study was to compare differences in frequency, frequency distribution of impact magnitudes, and time interval between head impacts per match between Lightweight and Heavyweight fighters in the Ultimate Fighting Championship (UFC). Head impacts of 60 fighters were documented from 15 Lightweight and 15 Heavyweight MMA fight videos. Impact type, frequency, and interval were recorded for each fighter, followed by the reconstruction of 345 exemplar impacts in the laboratory using a Hybrid III headform and finite element modeling to determine impact magnitudes. Next, head impacts (punches, kicks, knees and elbows) from fight videos were visually estimated to determine their corresponding magnitude range and establish the frequency distribution of impact magnitudes. The study revealed no significant differences in overall impact frequency and interval between Lightweight and Heavyweight fighters. The frequency distribution of different impact magnitudes was significantly different, with Lightweights sustaining significantly more Very Low, and High magnitude impacts. Overall, both Lightweight and Heavyweight MMA fighters sustain similar impact characteristics as other high-risk athletes including professional boxers and football players. Understanding the different factors that create brain trauma allows for the monitoring, identification, and protection of higher-risk athletes within these two weight classes.

Currently, low back disorder (LBD) research focuses primarily on mechanical variables to assess whether acute or cumulative task demands exceed the capacity of the tissue; however, it is important to assess how other non-mechanical variables affect tissue capacity in a time-dependent manner. The current investigation sought to explore physiological responses to an acute lifting task (similar to a typical assembly line task), as lifting has been implicated as a risk factor in the development of LBDs. Twelve participants completed two experimental sessions of two hours of repetitive symmetrical lifting from floor to knuckle height under a low force, high repetition condition (LFHR; box weighted at 5% maximum lifting strength, five lifts per minute) and a high force, low repetition condition (HFLR; 25% maximum lifting strength, one lift per minute), such that the external biomechanical work was equivalent between conditions. These sessions were completed one week apart, with full-body motion capture and ground reaction forces measured throughout. Systemic inflammation was assessed with blood sampling at baseline, 0, 4 and 24 hours post-lifting on both days, and samples were assayed using an ELISA for interleukin 6 (IL-6) and interleukin 8 (IL-8). Participants also completed psychological questionnaires including the Tampa Scale for Kinesiophobia-General (TSK-G), Pain Catastrophizing Scale, Visual Analogue Scale (VAS, participants 1-4) and Borg CR-10 Scale of Exertion (participants 5-12). There was a significant main effect of time on both IL-6 and IL-8 (Baseline, 0, 4, 24 hours), as well as interaction effects of condition (HFLR and LFHR) and time. The LFHR condition caused greater inflammation in both IL-6 and IL-8 at 0 and 4 hours post-lifting, likely due to significantly higher cumulative spinal loading in this condition. Significant correlations between body fat percentages, peak and cumulative loading were found to exist in both the LFHR condition and the HFLR condition, lending strength to the hypothesis that some of these measures may be able to predict physiological responses to acute stresses, and subsequently, risk of acute injury.