Neuromuscular biomechanics and environment - interaction in running

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Distance running has been shown to be an effective countermeasure for the development of cardiovascular and psychological diseases and has been proven to positively influence general well being. A negative side effect of running exercise is the high incidence of running related overuse injuries. Based on the latest review of the literature, between 19.4% and 79.3% of all runners suffer from running injuries within one year. Among other extrinsic and intrinsic risk factors, abnormal running biomechanics have been considered to predict the individual risk to sustain an overuse injury. Still, even though huge effort was taken into the investigation of biomechanical risk factors, only limited or even conflicting evidence exists for the predictive performance of certain parameters.
Currently, the predominant experimental approach to study individual running biomechanics does not take into account the variations of the running environment. The running environment is described by the characteristics of the running surface, the characteristics of the runner-ground-interface (i.e. footwear) and geographical characteristics. In the past, 3D running biomechanics were studied almost exclusively in a laboratory setting, at constant speed on a level, rigid running surface. Footwear modifications were analyzed only on one surface and interactions between footwear and ground modifications have not been systematically analyzed yet.
Therefore, the purpose of the present thesis was to analyze the effect of modifications of the running environment on human running biomechanics.
Joint kinematics were analyzed using an infrared based motion capture system (Vicon Nexus, Vicon Motion Systems, Oxford, UK). Ground reaction forces were measured using piezo type force platforms (Kistler, Instrumente AG, Winterthur, Switzerland). Marker trajectories, anthropometric information of the participants and force plate data were put into a five segment model of the right lower extremity that was used in all studies of the thesis. Inverse dynamics procedures were used to determine 3D joint moments and ground reaction force lever arms. Joint kinematics were calculated using the Cardan angle convention (order of rotation: 1. flexion / extension, 2, ab- / adduction, 3. internal / external rotation).
Different modifications of the running environment were performed, including modifications of the running surface stiffness and mediolateral tilting as well as modifications of the heel construction and midsole longitudinal bending stiffness of the running shoe. Further, barefoot and shod running were compared while running on different surfaces in order to investigate potential interactions between footwear and running surface.
The modification of the running environment had a clear impact on lower extremity running mechanics in all of the analyzed conditions. Strongest effects were found for those joints that are in close proximity to the induced modification of the running surface or shoe construction. In most cases this was the ankle joint. Still, effects were also detected for more proximal joints, even though effect sizes were smaller. Significant interactions between footwear and surface conditions could be identified, which shows that footwear interventions can lead to different responses in running biomechanics on different surfaces. Changes in the running environment seem to induce running style adaptations that lead to a shift of the point of force application, which is a mechanism that explains most of the alterations in joint kinetics observed in the individual studies of the thesis.
The results presented show that the running environment needs to be considered in the research on the relationship between individual biomechanics and overuse injuries. Further, the functional evaluation of footwear construction should include running on different surfaces, to give a complete picture on how it affects running biomechanics and joint loading. Here, the potential to change the point of force application seems to be a key variable that should be included in the standard assessment of footwear function. Future studies need to address the interaction between running environment and running biomechanics in greater detail. Further, individual response strategies in response to variations of the running environment should be investigated.
Original languageEnglish
Publication statusPublished - 2013

ID: 397364

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