Biomechanics of Baduanjin by AnyBody simulation and finite element modeling

“AnyBody” was used to demonstrate “three-element muscle contraction force” in skeletal muscle multi-body inverse dynamics. Three-dimensional tibia model of Baduanjin movement was constructed by finite element method. Integrated electromyography, torque, muscle contraction and other biomechanical characteristics at peak of maximum muscle force in different movements were calculated. The height, weight, hip width, hip depth, knee width, ankle width and other morphological data of 10 healthy young Baduanjin volunteers were used to obtain maximum muscle strength and other indexes of the lower limbs in eight movements of Baduanjin with “AnyBody 7.1.2”. Maximum stress constraint condition of the tibia was used to construct three-dimensional data with Minics 10.01, Geomagic studio 2013 and ANSYS 19.2. Data in three directions from “AnyBody” were then added, stress conduction size and distribution of the largest force in different directions were analyzed and calculated. Baduanjin was found to be an excise with left-right symmetrical movements. No significant difference in integral electromyography or muscle force of the same muscle on either side was found, conducive to stability and coordination of lower limbs. The human body needs to maintain balance through adjusted movements, the force of knee joint in the vertical direction was found to be the largest, with extension moment being the largest. During Baduanjin excercises, dominating hip joint driving muscles were gluteus medius, soleus, lateral femoris, gastrocnemius and flexor pollicis longus . Surface electromyography was the main method to evaluate activation of human muscles. Simulated muscle activities of tibialis anterior, gastrocnemius, rectus femoris and biceps femoris were found to be consistent with integral electromyogram. It is concluded that tibia model constructed by “AnyBody” and finite element software is suitable for dynamic study of Baduanjin movements.