自由体操落地冲击的下肢动力学仿真研究

Phantom Study on Kinetics of Lower Extremity during Landing in Floor Exercise

目的:约70%的自由体操损伤由落地冲击引发,本文旨在量化运动员下肢内、外负荷,为减少下肢损伤风险提供理论依据。方法:利用高速摄像机采集男子自由操团身后空翻一周落地站稳动作,以SIMI motion三维运动分析系统对人体主要关节进行三维运动学解析,用ADAMS/Lifemod创建个性化人体14环节刚体模型和自由体操落地垫模型,然后对采集的动作进行计算机仿真。结果:选择冲击前期、冲击后期、缓冲期3个阶段量化冲击负荷。外部负荷:冲击前期,人体承受最大冲击力约5倍体重,冲量和峰值负荷率最大。内部负荷:冲击前期,左踝关节的峰值负荷率最大(168W/kg),髋、膝、踝关节承受的冲击能量百分比分别为21%、21%、58%;冲击后期,矢状面,膝关节伸肌力矩峰值最大(161 N·m),冠状面,髋关节外展力矩峰值最大(154N·m)。结论:该方法可有效开展自由操落地冲击的动力学研究;对比髋、膝关节,踝关节肌肉承受着绝大部分的冲击能量,运动损伤风险最高。

Objectives The purpose of the study was to qualify the internal and external loads in lower extremity during landing in floor exercise,and provide theoretical reference for reducing risk of injury.Methods Movements of Arab spring back handspring and back somersault tucked were captured by two highspeed video cameras,and then kinematics data were digitized by using SIMI Motion 3D analysis software. A subject-specific model with 14-segment rigid body and a model of landing on mat in floor exercise were developed using simulation software of human movement ADAMS/Lifemod. Finally,computer simulation was performed. Results In regard to external loads,the peak ground reaction force of human body is about as high as five times of body weight. The largest impulse and the peak load rate of the ground reaction force appeared during the early phase of impact. In regard to internal loads,the largest loading rate of the left ankle joint（168 W/kg）was observed. The major energy absorbed by ankle plantarflexors（58%）,followed by the knee extensors（21%）and hip（21%）extensors during the early phase of impact. During the late phase of impact,the knee peak extensor muscle torque was 161 N·m and larger than hip joint on the sagittal plane,while the hip peak abduction muscle torque is 154N·m and larger than knee joint on the frontal plane. Conclusions The models developed in this study could be applied effectively to explore the dynamics during landing in floor exercise. Contrast to hip and knee joints,the ankle joints absorbed the majority of energy during landing,and thus was at highest risk of sports injury.