体操运动员完成高难度空中动作后要完美、稳定和安全的落地，但落地引起的踝关节损伤是他们面临的最大危险。影响落地时踝关节损伤的因素很多，但其生物力学机制仍不清楚。本课题首先实验测量分析优秀体操运动员神经肌肉系统（下肢关节力量、关节本体感觉和反应时间）和关键落地动作的生物力学特征；然后结合运动员的落地实际动作、生理解剖和力学参量建立落地动作的多刚体系统模型，并对关键落地动作进行动力学分析，获取地面反作用力、关节力/力矩等指标；同时基于运动员CT和MRI数据，建立踝关节有限元模型，计算分析关键落地动作载荷下踝关节的应力、应变和应变率的变化；最后通过计算机仿真方法，并结合实际损伤案例，探讨运动员神经肌肉系统特征、踝关节损伤史、空中和落地动作技术、环境力学特征等因素对踝关节负荷以及损伤危险性的影响。研究结果将为理解体操运动员踝关节损伤机制带来新认识，对体操运动员损伤的预防和动作技术的改进提供科学依据。

Gymnasts need to land with aesthetics, stability and safety after high-difficulty aerial movements, but they have to face the most serious threat, ankle injury. Epidemiological studies have suggested that gymnastics ranks the second injury rate for all sports. Ankle injury, such as ligamentous sprains, ligamentous or bone fractures, and impingement syndromes, is the highest injury among gymnastic injuries. Sound understanding the causes and mechanism of injury is vital to take measures for preventing the injury. It has been claimed that there are many factors affecting ankle injury, but the injury mechanism is not clear yet. Firstly, this proposal project will experimentally investigate biomechanical characteristics of neuromuscular system of elite gymnasts, which includes joint strengths and proprioceptions to angles in lower limbs, and reaction times to external signals. The subjects will be 30 elite gymnasts. Then, kinematics, kinetics, and surface electromyography (sEMG) of a few key landing movements performed by the elite gymnasts will be studied to investigate relationships between biomechanics and injury occurrences. These key landing movements will have been selected before the biomechanical tests among the routines that easily cause ankle injury. After that, a gymnast-specific multi-rigid body model for simulating gymnastic landing will be developed based on biomechanical, physiologic and anatomic parameters of the gymnasts. After incorporating the experimental data into the model, dynamics of the key landing movements will be analyzed with ground reaction forces (GRFs), lower limb joint forces, and joint torques obtained. In the mean time, a gymnast-specific finite element model of ankle will be developed based on computerized tomography (CT) and magnetic resonance imaging (MRI) data of the ankle, and the dynamic distributions of stress, strain, and strain rate of the ankle tissues during landing will be analyzed as well. According to the landing mechanical variables, such as GRFs, joint forces, joint torques, stresses, strains, and strain rates sustained, the risk of ankle injuries will be estimated. Finally, based on actual injury cases and the two models, a serial of computer simulations will be performed to analyze effects of the factors on risk of ankle injuries under landing loads. The factors include biomechanical characteristics of neuromuscular system, ankle injury history, landing techniques, and physic parameters of apparatuses. The physic parameters of apparatuses will be ground or mat stiffness, damping coefficient, friction coefficient, and dimension. This work would expand our knowledge of the mechanism of ankle injury during gymnastic landing, and further provide new scientific basis for injury prevention and performance enhancement.