| Background: Tai Ji Chuan’s sports efficacy of strengthening the body has been scientifically confirmed in many aspects,and its sports characteristics have also been widely recognized by people.Middle-aged and college students,as the main practice groups in Tai Ji Chuan,generally have nonstandard movement skills in the initial stage of practice,and even have problems such as knee discomfort or pain,which affects the benign development of Tai Ji Chuan’s technical inheritance and the sense of sports experience of practitioners.Objective: In this study,the differences of lower limb joint chain characteristics between beginners and inheritors in Tai Ji Chuan in practicing Ye Ma Fen Zong and Dao Juan Gong movements were explored by sports biomechanics,and the "weak link" joints of beginners’ lower limb movements were revealed.Methods: According to the calculation results of G*power sample size and the grouping admission standard,7 inheritors(inheritor group)and 16 beginners(middle-aged and elderly group: 7;College students group: 9 people)as the experimental object,using Vicon and AMTI equipment to collect the movement data of three groups of subjects’ "Ye Ma Fen Zong and Dao Juan Gong",and analyze the power,impulse and stiffness by one-way variance test.Results:(1)The characteristics of lower limb joint chain between beginners and inheritors are as follows: the range of motion of hip joint of beginners is significantly smaller than that of inheritors(P<0.05),and the range of motion of knee joint is significantly larger than that of inheritors(P < 0.05);The power and contribution rate of hip joint were significantly lower than those of inheritors(P<0.05),while the power and contribution rate of knee joint were significantly higher than those of inheritors(P<0.05).The impulse of supporting leg hip and ankle joint was significantly less than that of inheritor(P<0.05),and the impulse of knee joint was significantly greater than that of inheritor(P < 0.05).Stiffness of hip and knee joint of supporting leg is significantly higher than that of inheritor(P<0.01),and stiffness of ankle joint is significantly lower than that of inheritor(P<0.01).The difference between beginners’ groups is that the knee joint power,contribution rate and ankle joint stiffness of middle-aged and elderly people are significantly higher than those of college students(P<0.05).(2)At the peak moment of supporting leg flexion,the difference of lower limb posture chain between inheritors and beginners is that the flexion and abduction angles of beginners’ left hips and knees are significantly smaller than those of inheritors(P < 0.05);Among the beginners,the flexion angles of left hip and left knee in the middle-aged and elderly group were significantly smaller than those in the college students group(P<0.05).Conclusion:(1)There is a high similarity in the characteristics of joint chains among beginners,but there are obvious differences with those of inheritors;Inheritors are good at using the characteristics of hip-ankle joint chain to complete the action,while beginners rely on the joint chain dominated by knee joint to complete the action.(2)The "weak link" phenomenon of beginners’ hip joint,such as insufficient movement angle,low participation in doing work,too little impulse and too high stiffness,has triggered the characteristics of posture chain and power chain dominated by knee joint,which is the main factor affecting the development of "knee bending and hip opening" and "round crotch opening" techniques.(3)Beginners should focus on the participation of hip joint in the exercise process to avoid the potential risk of knee joint pain caused by excessive dependence on knee joint to complete the action. |
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