The effect of strike pattern on the cushioning capacity of technical midsole footwear

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Τζοβλά, Αικατερίνη
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Numerous research studies have highlighted the interconnection between footwear and running strike patterns [1]. The processes that govern these adjustments in movement patterns are generally acknowledged to depend on the perception and transmission of impact forces through the musculoskeletal system of runners [2]. Consequently, a variety of midsole technologies have been developed in recent years to cater to the requirements of both professional and regular runners. Despite extensive efforts dedicated to understanding the intricacies of running biomechanics and mitigating impact, the impact of foot placement on the cushioning capacity of specific midsole systems remains poorly understood. The purpose of this project was to determine the extent to which Finite Element (FE) modelling techniques can determine how different strike patterns relate the energy absorption capacity of technical footwear. To obtain detailed information about a commercial running shoe, a micro-Computed Tomography device (Werth TomoScope® HV Compact-225 3D CNC) was utilized for scanning purposes. The gel-based midsole of the shoe was accurately reverse-engineered with a precision of 200μm. Subsequently, the obtained model was processed using ANSA software by BETA CAE Systems S.A., where the meshing of the model was performed. Convergence studies were conducted to ensure the grid's accuracy and independence, resulting in a mesh that met the desired quality criteria. For the analysis, two distinct strike patterns were taken into account: heel-strike (HS) and forefoot strike (FFS). To capture the plantar pressure distributions during running for both strike patterns, a Footscanner insole 2.39 system (Niceville, FL 32578, USA) was utilized. Additionally, the shoe-ground contact duration, which varies with time, was obtained from high-speed camera measurements using the MotionBLITZ EoSens® mini. Data collection was focused on female endurance athletes, with an average weight of 51 kg ± 0.82 kg. All recorded data underwent a filtering process and were statistically normalized to ensure accuracy and consistency. Under dynamic conditions, load and boundary conditions were applied to both the superior and inferior surfaces of the 3D midsole. The Finite Element (FE) analysis specifically considered four key phases of the running cycle: touchdown, impact peak, end of mid-stance, and toe-off. Based on the evaluation process, it was determined that during forefoot strike (FFS), the maximum ground reaction force was found to be 6.7% higher compared to heel strike (HS). Additionally, the support phase duration for HS was slightly prolonged by approximately 9.2%. These findings indicate that FFS involves a more energy-intensive foot-strike, which aligns with existing literature [3].
Strike pattern, Midsole footwear, Finite element