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 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.

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.