Masters Thesis

Differences in Muscle Architecture of the Gastrocnemii and Tibialis Anterior between Forefoot and Rearfoot Runners

Running related injuries are related to foot strike pattern (FSP). Cross-sectional area (CSA), pennation angle (PA), and fascicle length (FL) of the lower limb musculature contribute to plantarflexion (PF)/dorsiflexion (DF) strength, and may influence FSP. the purpose of this investigation was to compare CSA, PA, and FL of the medial and lateral gastrocnemii (MG and LG, respectively) and tibialis anterior (TA) between forefoot (FF) and rearfoot (RF) strikers and to investigate associations between FSI, CSA, PA, and FL. 33 recreational runners (22 male/11 female; age = 22.26 ± 3.01 years; height = 1.72 ± .08 m; mass = 65.20 ± 8.97 kg) participated in this study. CSA, PA, and FL of the MG, LG, and TA were assessed using ultrasonography. PF and DF maximal strength values were obtained using handheld dynamometry. FSP was obtained using foot strike index (FSI), and 15 RF, 2 midfoot, 16 FF strikers were identified. Midfoot strikers were excluded from analysis. Spearman rho rank order correlation was used to evaluate the association between FSI and CSA, PA, FL, and strength; whereas Pearson product moment correlation (r) was used to evaluate relationships between strength and ultrasound measurements. ANCOVA analysis was used to compare dependent variables between groups. RF strikers demonstrated lesser TA EI, steeper TA PA, and lesser LG PA compared to RF strikers. There are lower limb muscle architectural and geometric differences that influence FSP, and are amenable to tailored interventions. These features should be considered when transitioning FSP in long distance runners.

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