疾跑中腘绳肌肌纤维长度的在体测量及肌肉负荷的计算机模拟

Hamstring muscle strain injury is the one of most prevalent injuries in sports. It occurs most often in the long head of biceps femoris. Due to lack of in vivo measurements of muscle fiber length change during springing, there are debates in the literature regarding the injury mechanisms. Our previous study proposed “Excessive muscle strain as the direct cause of injury” should not be generalized to hamstring muscle strain injury in sprinting”. We will test this statement by measuring muscle fiber length of biceps femoris in vivo during sprinting. Additionally, 3D kinematics, 3D kinetics, EMG during sprinting will be collected and computational simulation of muscle loading in biceps femoris will be conduced by OpenSim. We will mainly examine the following hypotheses: 1. Muscle fiber length of bicep femoris does not change significantly during the late swing phase; 2. Muscle loading in biceps femoris increases sharply during the initial stance phase; 3. Acute effects of stretching exercises and chronic effects of eccentric exercises could reduce hamstring injury risk during sprinting by right shifting the length-tension curve. The results of proposed studies may bring insight to mechanisms of hamstring strain injury in sprinting and effective methods to reduce injury risk. Additionally, the results of proposed studies may be used to improve musculoskeletal model in OpenSim for sprinting simulation.

腘绳肌拉伤是最常见的运动损伤，常发生在股二头肌长头。由于缺乏运动中肌肉在体测量数据，理论界对肌肉拉伤机理还存在争议。同时，拉伤究竟是发生在摆动末期还是支撑前期也存在争议。我们前期的研究提出了"肌肉过度拉长导致拉伤并不适用于疾跑中腘绳肌的拉伤"的观点。为验证此观点，我们拟在三维运动学，动力学，表明肌电等测量方法的基础上增加无线超声设备在体测量疾跑中股二头肌肌纤维的长度。并利用openSim模拟仿真软件估算疾跑中股二头肌的负荷。重点验证以下科学假设：1. 疾跑中摆动末期股二头肌肌纤维长度处于近似等长状态； 2. 支撑前期肌肉负荷瞬间急剧增加；3. 运动前拉伸的短时效应及离心训练的长时效应都能使肌肉长度—肌力曲线右移，从而降低拉伤风险。研究结果将：1）揭示疾跑中腘绳肌拉伤的机理，并以此为基础提出有效预防腘绳肌拉伤的方法；2）完善用于模拟疾跑中下肢动力学的opensim肌骨模型。

腘绳肌拉伤是最常见的运动损伤，常发生在股二头肌长头。由于缺乏运动中肌肉在体测量数据，理论界对肌肉拉伤机理还存在争议。同时，拉伤究竟是发生在摆动末期还是支撑前期也存在争议。我们前期的研究提出了"肌肉过度拉长导致拉伤并不适用于疾跑中腘绳肌的拉伤"的观点。为验证此观点，我们在三维运动学，动力学，表明肌电等测量方法的基础上增加了在体超声测量疾跑中股二头肌肌纤维的长度。并利用OpenSim模拟仿真软件和数学模型估算疾跑中股二头肌的负荷。此外，我们还进行了北欧腘绳肌和疾跑的生物力学特征对比，检验了静态拉伸与北欧腘绳肌对腘绳肌肌力及肌肉形态的即刻影响，静态拉伸对加速跑的影响等研究。我们发现疾跑中摆动末期股二头肌肌纤维长度处于近似等长状态，整个步态周期肌纤维长度变化不超过1.5厘米;支撑前期肌肉负荷有所增加;运动前北欧离心训练的短时效应与静态拉伸相似，两者结合效果更好；静态拉伸有助于减少加速跑中的负荷。本研究的结果支持腘绳肌拉伤是由应力过大导致局部应变过大。预防腘绳肌拉伤的干预包括静态拉伸结合北欧腘绳肌练习，以及提高加速跑的姿态控制，减少步与步之间的突然变异。