The Comparison of Knee Joint Kinematics,Joint Load and Muscle Activity Characteristics for Tai Chi Basic Action “the Wild Horse’s Mane on Both Side”

Objective:The aim of this study was to compare the biomechanical characteristics of lower extremity in conducting the“part the wild horse's mane on both side”of Tai Chi maneuver in a correct and a wrong form.In order to find the possible cause of the knee injure of Tai Chi and prevent such kind of injure effectively, the kinematics, joint loading, and muscle activity of the knee joint was therefore explored.Methods:the subject was a top-level female athlete (41 years of practicing Tai Chi) .The test movement was a Tai Chi maneuver called“part the wild horse's mane on both side” (in a correct and a wrong form) .A Vicon system, two Kistler forceplates, and a Delsys surface EMG system were synchronously used to collect the kinematics, ground reaction forces, and EMG activity from the quadriceps and the hamstring muscles of the knee joint.Paired T-test was applied to compare the differences (joint angle, joint torque, and muscle activity) between the two forms.Results& Conclusion:The time of each stage and the movement circle was significantly higher in wrong form of Tai Chi compared with the correct form.Meanwhile, a significant larger angle in knee joint abduction and internal rotation was showed in the wrong from.During the whole procedure of the movement, a dominated torque was showed in the extensor of the right knee joint.However, a significant larger torque in the abduction and external rotation of the knee joint was also observed.During the foot switch, the vastus medialis and vastus lateralis muscle activity were significantly greater in the wrong form, which showed a resistance to the great loading on the knee caused by the wrong movement.The above results implied that the knee injury would be induced due to the wrong form during a long-term Tai Chi exercise.