The flexible multibody simulation [9] approach can be used in a wide variety of engineering applications. In a previous study of authors [1], flexible multibody simulation approach was used to estimate strains during walking at tibial midshaft. In the previous study, simple muscle models were used in conjunction with a flexible tibia model based on magnetic resonance images (MRI). This study is an extension of the previous developments [1], [2] demonstrating the potential of model improvement by introducing hybrid muscle models, along with the flexible tibia based model on computed tomography (CT). The computed tomography technique allows for the accounting of inhomogeneous density and elasticity in the flexible bone model comparing to magnetic resonance which do not provide any information on material properties. Hybrid muscle configuration used in this study consists of electromyography (EMG) actuated simple muscles configured with open-loop control for soleus, tibialis anterior, gastrocnemius and rectus femoris muscles and closed-loop Hill-based muscles [13] for the remaining lower body muscles. Strain results introduced in the study show good correlation with previous studies.