Presenter(s): Hao Tan − Human Physiology
Co Presenter(s): Colin Lipps
Faculty Mentor(s): Li-Shan Chou, JJ Hannigan
Poster 24
Research Area: Natural/Physical Science
Funding: UROP Mini-Grant, Sue Grigsby Scholarship, William and Marjorie Shearon Memorial Scholarship
Existing literature has identified several risk factors for the development of lower limb pathologies in recreational runners, including hip abductor muscle strength deficits as well as abnormal patterns in pelvic running kinematics. Studies have indicated that hip abductor muscles play a role in stabilizing the hip during running and that hip abductor strength deficits are associated with the development of overuse injuries as well as abnormal pelvic kinematics while performing tasks upright. However, the relationship between hip abductor strength deficits and abnormal pelvic kinematics while running remains unclear. This study intends to clarify the relationship between hip abductor muscle fatigue and associated pelvic kinematic changes in healthy runners by implementing a novel 30-minute lactate threshold treadmill run as a fatigue protocol while investigating pelvic kinematic changes at 7 equidistant time points over the course of the protocol. In terms of analyzing pelvic kinematics, this study implemented a dynamical systems approach, analyzing the variability of Trunk-Pelvis and Pelvis- Thigh segment couplings in the 3 anatomical planes, as well as an analysis of individual pelvic kinematic variables, specifically pelvic drop, hip adduction, trunk lean, and hip internal rotation. 23 subjects, between the ages of 18 – 40 who have not sustained major running related injuries and regularly run at least 20 miles a week, participated in this study. Participants performed a triplet of hip abductor muscle maximal voluntary contractions (MVCs) to establish a baseline and a post-fatigue strength assessment before and after a 30-minute fatiguing run, during which kinematic changes were assessed. Using a significance threshold of 0.05, it was found that hip abductor strength decreased significantly following the fatigue protocol (p < 0.0001) while pelvic drop significantly increased following the fatigue protocol (p < 0.001). No significant changes were observed in trunk lean, hip adduction, or hip internal rotation. The results of a repeated measures one-way ANOVA used on the entire participant pool indicated that there were no significant changes in variability between the 7-time points for both Trunk-Pelvis and Pelvis-Thigh coupled segments in the three anatomical planes. However, paired t-tests indicated that female participants experienced a significant decrease in variability within the sagittal plane of Pelvis-Thigh (p < 0.001) coupled segments and the frontal plane of Trunk-Pelvis (p < 0.01) coupled segments following the fatigue protocol. The experimental results indicate that a 30-minute lactate threshold treadmill run is an effective method of inducing hip abductor fatigue and potential increases in pelvic drop. Additionally, the findings of the dynamical systems approach used implicates that females may be more prone to lower limb overuse pathologies, which is consistent with the experimental findings of past studies.