Contributions of individual muscle forces to hip, knee, and ankle contact forces during the stance phase of running: a model-based study.

Knowledge of muscle forces' contributions to the joint contact forces can assist in the evaluation of muscle function, joint injury prevention, treatment of gait disorders, and arthroplasty planning. This study's objective was to evaluate the contributions of human lower limb muscles to the hip, knee, and ankle joint contact forces during the stance phase of running. A total of 25 muscles (or groups) were investigated based on the OpenSim framework along the anterior-posterior, superoinferior, and mediolateral components of each joint coordinate system. It was revealed that, during the running stance phase, the gluteus medius, gluteus maximus, and iliopsoas mainly contributed to the hip contact force. The soleus, vastus group, and rectus femoris primarily contributed to the knee contact force, while the peroneus, soleus, gluteus medius, and gastrocnemius mainly contributed to the ankle joint force; some muscles simultaneously offloaded the joints during the stance phase. The distributive pattern of the individual muscle functions contributing to the joint load may substantially differ during the running and walking stance phases. This study's findings may further provide suggestive information for the design of lower limb joint prosthesis, the study of the biomechanics of pathologic walking and running, and the progression of joint osteoarthritis.