The aim of the current investigation was to utilize a musculoskeletal simulation-based approach, to examine the effects of barefoot and shod running on lower extremity joint loading during the stance phase. Twelve male runners, ran over an embedded force plate at 4.0 m/s, in both barefoot and shod conditions. Kinematics of the lower extremities were collected using an eight-camera motion capture system. Lower extremity joint loading was also explored using a musculoskeletal simulation and mathematical modelling approach, and differences between footwear conditions were examined using paired samples t tests. Peak Achilles tendon force was significantly larger (P = 0.039) when running barefoot (6.85 BW) compared to shod (6.07 BW). In addition, both medial (P = 0.013) and lateral (P = 0.007) tibiofemoral instantaneous load rates were significantly larger in the barefoot (medial 289.17 BW/s and lateral 179.59 BW/s) in relation to the shod (medial 167.57 BW/s and lateral 116.40 BW/s) condition. Finally, the barefoot condition (9.70 BW) was associated with a significantly larger (P = 0.037) peak hip force compared to running shod (8.51 BW). The current investigation indicates that running barefoot may place runners at increased risk from the biomechanical factors linked to the etiology of chronic lower extremity pathologies. However, future analyses using habitual barefoot runners, are required before more definitive affirmations regarding injury predisposition can be made.
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