The purpose of this study was to analyze the activity of ankle muscles during normal gait by simulation method using the human musculoskeletal model. The equipment used in this study was three-dimensional motion capture system and force platform, and OpenSim was used for simulation. Collected data was scaled to Gait2392 that is the human musculoskeletal simulation model using in the OpenSim. Tibialis anterior (TA) worked as a major muscle during gait, producing a higher force than other muscles. Main muscles contributing to propulsion were gastrocnemius medial head (GMH) and soleus (SOL) with their maximum forces appear to be more than 1.5 times the body weight. GMH and SOL showed cooperation for maintaining propulsion around left foot initial contact in the gait cycle. This study has shown a difference between activation and force pattern. The peak-activation of the TA and extensor digitorum longus (EDL) was similarly shown to be around 0.8 in the initial double stance, but the peak-force produced by these muscles in the same period showed a difference with 0.4 Newton/body weight higher in TA than in EDL. We suggest that when assessing muscle contribution to gait, it would be reasonable to consider the force generated because the human movement was generated by the mechanical net force of muscles.
Keywords: Ankle muscles; Contribution; Muscle force; OpenSim; Simulation.