The Effect of Core Stability on Running Mechanics in Novice Runners DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Margaret Elisabeth Raabe Graduate Program in Biomedical Engineering The Ohio State University 2017 Dissertation Committee: Ajit MW Chaudhari, PhD, Advisor Alan S Litsky, MD, ScD Robert A Siston, PhD Thomas M Best, MD, PhD Copyrighted by Margaret Elisabeth Raabe 2017 Abstract Despite the many health benefits associated with running, the annual running injury rate has been reported to be as high as 74%, and novice runners may be at the highest risk of developing these injuries. Research has shown core stability may affect lower extremity function, leading to the popular notion that insufficient core stabilization may lead to less efficient movements that ultimately contribute to musculoskeletal injury. However, the role that core stability plays during running and its influence on injury risk is not well understood. The purpose of this dissertation was to establish the effect of core stability on fundamental mechanisms of running-related injuries and to investigate possible compensation strategies for reduced core stability. Chapter 1 provides background information on running injuries, injury mechanisms, and core stability and describes the benefits of using dynamic simulations in combination with experimental data. Chapter 2 experimentally investigated the direct downstream effects of reduced core stability on running mechanics in novice runners and found reduced core stability was significantly associated with an increased external peak knee flexion moment (13.5±2.5 %BW*h vs 14.3±3.1 %BW*h, p=0.001) during the stance phase of running, which has previously been associated with increased patellofemoral joint loading. Chapter 3 describes the development and validation of an OpenSim model that allows for the creation of simulations investigating full-body ii dynamics and contributions of the trunk muscles to dynamic tasks. In Chapters 4 and 5, the experimentally collected data from Chapter 2 was used with the model developed in Chapter 3 to investigate the consequences of utilizing different possible compensation strategies for reduced core stability. Chapter 4 assessed the biomechanical consequences of altering running kinematics (kinematic compensation strategy) in response to reduced core stability and found this strategy was associated with increased internal knee loading during the stance phase of running (peak patellofemoral joint reaction force, p=0.029; knee abduction moment peak and impulse, p=0.01, p=0.02, respectively; peak knee extension moment, p=0.09), as well as reduced energy consumption (p=0.059), spinal loading (p≤0.06), and select peak core muscle forces (p≤0.06). Chapter 5 investigated utilizing a neuromuscular compensation strategy (altering only muscle activation strategies and maintaining kinematics) in response to core muscle fatigue and found this strategy was not associated with any change in estimated energy consumption or lower extremity loading during stance. Increased deep core muscle force production was observed as the only muscular compensation following core muscle fatigue, suggesting this may be the primary adjustment required to achieve a neuromuscular compensation strategy in the presence of core muscle fatigue. Therefore, insufficient core stability in novice runners may increase lower extremity loading and ultimately running injury risk. A core neuromuscular training program emphasizing increased engagement and force production of the deep core muscles may give runners the ability to maintain movement patterns and utilize potentially lower-risk compensation strategies, such as a neuromuscular strategy, when core stability is compromised. iii Understanding how core stability affects running mechanics and potential compensation strategies used for poor core stability may ultimately contribute to the development of more effective and robust running injury prevention and rehabilitation regimens. The information presented in this dissertation improves the basic understanding regarding the influence of core stability on running mechanics in novice runners. This work will contribute to achieving the long-term goal of ultimately reducing the incidence of running-related injuries in novice runners. iv Dedication For my family -- Without you none of this would have been possible. v Acknowledgments This research would not have been possible without the help and guidance of many people. I would first like to thank my advisor, Ajit Chaudhari, who provided endless guidance, mentorship, and support throughout all phases of this project. He has shaped me into the scientist I am today and I would not have made it this far without him. I would also like to thank the other members of my dissertation committee; Alan Litsky, Rob Siston and Tom Best. They each contributed a valuable perspective and expertise to this project, greatly improving the project’s quality and potential impact. Additionally, each committee member has been instrumental in my professional and personal growth over the past 5 years. I am extremely grateful to have been a part of such a unique, interdisciplinary scientific environment in the Movement Analysis and Performance Laboratory and the Sports Biomechanics Laboratory at Ohio State. Specifically, I would like to thank Jimmy Oñate who has also provided support, guidance, and large contributions to many parts of this project; Scott Monfort, who has been by my side since day one, brainstorming, endlessly piloting protocols, collecting and analyzing data, troubleshooting, and providing instrumental feedback and collaboration; and Mike McNally, who was always been there to answer questions and provide support in any way possible. I would also like to thank Andrea Wanamaker, Greg Freisinger, Jackie Lewis, Chris Nagelli, Justin Creps, vi Louise Thoma, Elena Caruthers, Sarah Schloemer, and everyone else in the lab for all the help and feedback they have provided along the way. I would like to acknowledge the funding sources that supported multiple parts of this project: The Ohio State University’s Graduate School, The Ohio State University Department of Biomedical Engineering, The National Institute of Arthritis and Musculoskeletal and Skin Diseases, and The Ohio State University School of Health and Rehabilitation Sciences. Additionally, I would like to thank all my friends for providing support and encouragement during this process, as well as making sure I always kept some necessary balance in life. Specifically, Leiah, Allie and Erica, who all put up living with me during some of the most stressful times, and Greg, who has stood by me and has endlessly supported me even from hundreds of miles away. Finally, and most importantly I would like to thank my family. Without them I would not have realized my passion for math, science and engineering, and would not have had the support to pursue this journey. I am extremely thankful for their unconditional love and encouragement, and the superb values and work ethic they instilled in me. It is only because of them that any of this was possible. vii Vita 2008 ...............................................................High School Diploma, Bexley High School 2012 ...............................................................B.A. Physics, The College of Wooster 2015 ...............................................................M.S. Biomedical Engineering, The Ohio State University 2012 to present ..............................................Graduate Research Associate, The Ohio State University Publications Raabe, M. E. and A. M. W. Chaudhari (2016). "An Investigation of Jogging Biomechanics using the Full-Body Lumbar Spine Model: Model Development and Validation." Journal of Biomechanics 49: 1238-1243. Fields of Study Major Field: Biomedical Engineering viii Table of Contents Abstract ............................................................................................................................... ii Dedication ........................................................................................................................... v Acknowledgments.............................................................................................................. vi Vita ................................................................................................................................... viii Publications ...................................................................................................................... viii Fields of Study ................................................................................................................. viii Table of Contents ............................................................................................................... ix List of Tables ................................................................................................................... xiv List of Figures ................................................................................................................. xvii List of Abbreviations ..................................................................................................... xxiii Chapter 1 : Introduction ...................................................................................................... 1 1.1 Running Injuries .......................................................................................................