The effect of load carrying on the human lower extremity muscle activation during walking

This paper focuses on the biomechanical aspects of human load carrying in order to provide a physiological framework for designing the more anthropometric assistive systems. An 8-degrees-of-freedom musculoskeletal model with twenty functional muscle groups in the lower extremity was developed to simulate the movement in sagittal plane. Inverse dynamics based optimization approach was employed to estimate the excitation level of the muscles. Activation patterns of the muscles illustrate the importance role of the soleus in supporting of the body during load carrying. Also power distribution analysis of the muscles reveals that the plantar flexors of the ankle, extensors of the knee and hip joints exhibit distinct functional differences between normal walking and load carrying conditions. As a result anthropometric assistive mechanism should contain actuators providing additional extension torque in the hip and knee joints and plantar flexion torque in the ankle joint.