短跑运动中下肢环节间互动动力学分析

目的从动作控制角度出发,探讨运动控制对提高短跑运动成绩以及预防运动损伤的可能影响。方法研究对象为8名国家级优秀短跑运动员(最好成绩:10.27s～10.80s),利用8台红外高速摄像系统(采样频率300Hz)与测力台系统(1200Hz)同步记录受试者在短跑最大速度阶段的运动学与动力学地面反作用力资料。根据逆动力学理论建立下肢多环节互动动力学模型,对短跑一个步幅的各种力矩进行量化分析。结果短跑支撑阶段地面反作用力矩是下肢各关节处的主要被动力矩,它在着地初期对膝关节产生一个较大的伸膝作用,腿后肌为抵抗此力矩的     

老年人下楼梯下肢关节做功模式分析

目的 探究下楼梯行走过程中老龄化对老年人下肢关节做功模式的影响,丰富楼梯行走的防跌倒理论。 方法 采用 Vicon 红外运动捕捉系统和 Kistler 三维测力台同步采集青年人和老年人下楼梯行走的运动学和动力学数据,利用下肢关节角度、力矩、功率、做功贡献度指标对下肢关节做功模式进行量化评定。 结果 下楼梯过程中,青 年组和老年组下肢三关节角度、力矩、功率的变化趋势一致。 在优势腿的 1 个支撑相内,老年人的屈髋力矩峰值、伸膝力矩第 1 峰值、第 2 峰值、跖屈力矩第 1 峰值、膝负功率第 1 峰值、第 2 峰值、踝负功率峰值以及髋、膝、踝关节净功均显著降低(P<0. 05);伸髋力矩峰值、髋负功率峰值、踝关节做功贡献度显著增加(P<0. 05),髋、膝关节做功贡献度并未出现显著性差异(P>0. 05)。 结论 在下楼梯过程中,老年人下肢关节力学特征显著降低。 老年人采取不同于青年人的下肢关节做功模式。 老年人通过较大的伸髋姿势抵制躯干的过度前倾,同时采取踝关节做功的代偿模式,提高下楼梯行走的身体稳定性。 建议老年人在锻炼时应以增加膝、踝关节肌肉力量的项目为主,以维持下楼梯的姿势控制能力。     

不同躯干约束下蹲姿对人体下肢运动学和动力学的影响

目的 探究躯干控制对青年群体亚洲蹲和西方蹲时下肢运动生物力学特征的影响,为深蹲训练的应用和推广提供实证性依据。方法 24名健康男性青年大学生在带杆、无杆控制条件下进行亚洲蹲和西方蹲,运用红外光点运动捕捉系统和三维测力台采集其下肢运动学和动力学特征。通过Cortex-642.6.2软件,根据欧拉角方法计算获得下肢三维角度,运用逆动力学方法得到三维力矩。通过2×2重复设计的双因素方差分析检验躯干控制和深蹲姿势对下肢运动特征的影响。结果 躯干控制和深蹲姿势对运动学和动力学参数均无显著性交互作用(P>0.05)。西方蹲具有较大的膝关节屈曲角、髌股关节接触力峰值、髋膝伸展力矩峰值之比,较小的踝关节背屈角、髋关节屈曲角(P<0.05)。带杆深蹲具有较大的踝关节背屈角、髌股关节接触力峰值和髋关节屈曲角,较小的膝关节屈曲角、髋膝伸展力矩峰值之比(P<0.05)。结论 西方蹲有助于训练伸髋肌群肌力,亚洲蹲则有助于训练伸膝肌群肌力。西方蹲髌股关节接触力峰值显著大于亚洲蹲,故推荐髌股关节痛患者采用亚洲蹲。带杆深蹲可补偿人体平衡,建议由于踝关节背屈活动范围受限或胫骨前肌无力人群可以考虑进行带...     

人体坐立运动的膝关节动力学研究EI北大核心CSCD

坐立运动是人体最常见的运动行为之一,膝关节是人体坐立运动的主要承力关节,因此进行坐立运动过程的膝关节动力学研究具有重要意义。基于力矩平衡原理对坐立运动的膝关节动力学进行分析,结合光学动作捕捉和六维支撑力测试所得数据,计算求得膝关节力矩曲线。为了验证实验数据和动力学分析的准确性,建立人体模型,根据实验数据拟合角度和角速度多项式方程,进行坐立运动的膝关节动力学仿真。结果显示计算数据和仿真数据在范围和变化趋势方面一致。综合膝关节力矩变化规律,揭示了膝关节力矩与地面反作用力的关系。坐立运动中膝关节力矩和地面反作用力成正比关系,比值为5~6,且由坐到立过程中,加速度先增大后减小最后反向增加,力矩最大值发生在膝关节夹角约140°时,而由立到坐过程中,力矩在初始阶段最大。坐立运动的膝关节动力学研究结果有益于坐立康复辅具的优化设计及力反馈控制,并可为膝关节康复训练提供理论指导。     

不同硬度楔形鞋垫对膝关节内翻力矩的影响

目的研究不同硬度楔形鞋垫在步行状态下对膝关节内翻力矩的影响。方法 15名健康成年男性受试者穿着不同硬度楔形鞋垫进行步态测试,通过光学运动捕捉系统和地面测力板收集运动学和动力学数据,经Visual3D软件计算得出膝关节内翻力矩,分析在3种不同步行状况下(仅穿鞋、鞋中放入软、硬楔形鞋垫)膝关节内翻力矩峰值的差异。结果与较软的楔形鞋垫相比,较硬的楔形鞋垫可使膝关节内翻力矩的第1个峰值降低9.3%,第2个峰值降低9.7%,差异具有统计学意义。结论楔形鞋垫增加一定的硬度能更多降低膝关节内侧间室的压力,减轻关节面的磨损,从而可能缓解膝关节炎症状。     

直线前进变换为侧向跨步切入动作时的下肢生物力学变化

背景:侧向跨步切入动作是运动领域最常见的进攻技术,这显著增加了运动员膝关节受伤的风险,但目前相关侧向跨步动作的生物力学表现策略及下肢关节负荷特征并不十分清楚。目的:选择大学女子甲组篮球、足球运动员进行侧向跨步切入下肢动作策略,进行生物力学测试,并分析下肢关节的运动学及动力学参数,从而为运动员及教练员预防下肢伤害,尤其是膝关节十字韧带损伤提供重要参考。方法:选择某高校女子甲组足球及篮球各12名运动员作为研究对象,利用三维测力台及运动图像拍摄系统同步获取其侧向跨步切入动作的相关运动学及动力学参数,并运用SPSS 21.0分析软件对相关数据进行处理分析。该试验方案经天津体育学院伦理委员会批准。结果与结论:①足球运动员有较大的着地瞬间踝关节跖屈角度及髋关节外展角度、最大踝关节外翻角度、膝关节屈曲及内旋角度、膝关节屈曲及内旋角度变化量;②足球运动员有较大的踝关节外旋与髋关节内收力矩峰值,篮球运动员则有较大的踝关节跖屈力矩峰值;③篮球运动员有较小的前后分力制动第一及第二峰值、垂直分力第一峰值及较大的前后分力推蹬力峰值;④结果表明,跨步切入动作过程中,足球运动员习惯于前足着地方式进行急停,进而产生较高的地面反作用力,并增加膝关节屈曲角度进行缓冲,同时有较大的踝关节外翻角度及膝关节内旋角度,而篮球运动员在切入过程中膝关节屈曲角度较少,不利于下肢关节对地面反作用力的缓冲,并进而增加前十字韧带损伤风险。     

冲击载荷作用下运动员下肢动态响应的逆向动力学仿真

目的分析冲击载荷作用下羽毛球运动员下肢关节肌肉的动态响应变化。方法基于Any Body Modeling System软件建立人体肌骨模型,采用实测表面肌电信号进行验证,以运动捕捉系统和测力台测量数据进行模型驱动,对羽毛球右前场蹬跨步上网过程中下肢肌肉肌力、关节力和关节力矩进行逆向动力学仿真与分析。结果所建人体下肢肌骨模型经肌电信号验证有效。羽毛球蹬跨步上网过程中,髋、踝关节Z方向内力峰值显著高于X和Y方向内力峰值,而膝关节X方向内力峰值显著高于Y和Z方向内力峰值;缓冲期,髋关节X、Y、Z方向依次表现为内收力矩、伸髋力矩和内旋力矩,膝关节X、Y、Z方向依次表现为外展力矩、屈膝力矩、外旋力矩,踝关节X、Y方向依次表现为内翻力矩、跖屈力矩,且髋、膝、踝关节X方向力矩峰值显著高于Y和Z方向;股外侧肌、股二头肌、胫骨前肌、腓肠肌内侧在对抗地面冲击载荷时的肌力发挥较大,股直肌、半膜肌、比目鱼肌发挥的作用相对较小。结论建立的下肢肌骨模型可为冲击载荷作用下运动员下肢生物力学特性分析提供技术平台。为避免运动损伤,类似羽毛球前场蹬跨步上网冲击动作中尤其要重视触地瞬间地面反作用力载荷对髋、膝、踝关节前后及内外侧方向生物力学性质的影响,同时在对羽毛球运动员进行专项训练时切勿忽视对股外侧肌、股二头肌、胫骨前肌的专项力量发展。     

基于Hill肌肉模型的人体关节力矩智能预测

目的人体关节力矩是康复评估和人机交互中非常关键的因素之一。它可以通过人工神经网络(artificial neural network,ANN)模型以肌电等信号作为输入进行预测,但是由于人体结构的复杂性导致缺乏有效方法确定ANN模型的输入变量。为此本文提出了一种基于Hill肌肉模型获取关节力矩神经网络预测最优输入变量的方法。方法采用Hill肌肉模型结合人体几何学知识建立关节力矩,智能预测输入输出关系的数学模型,把Hill肌肉模型中肌肉纤维长度和收缩速度,以及以关节自由度为支点的肌肉力臂等不可活体测量的输入变量,转换成关节自由度所关联肌肉的肌电信号(electromyography,EMG)以及这些肌肉所驱动关节自由度角度和角速度等可在线测量的变量。实验中以本文获取的变量作为极限学习机(extreme learning machine,ELM)的输入,对由1位在跑步机上以0.4、0.5、0.6、0.7和0.8 m/s等5个不同速度行走的右下肢偏瘫患者所获的数据进行测试。为了评估本文所提方法智能预测的泛化能力,实验在两个不同的泛化水平下进行,它们分别是只把3个低速数据(0.4、0.5和0.6 m/s)和全部5个速度的数据用于神经网络的训练并预测所有速度下的关节力矩值。实验通过预测值与反向动力学计算值之间的归一化绝对误差和互相关系数评估。结果本文获取的输入变量与其他关节角和角速度作为输入的方法相比,预测关节力矩值更精准。除右踝关节内外翻外,其他关节力矩预测结果的最大归一化绝对误差为12.93%,最小平均互相关系数为0.89。结论该方法比目前通用多体反向动力学的输入变量少,且可实现关节力矩值的在线预测,为运动康复中实时步态分析和外骨骼机器人控制提供技术支持。     

利用步态分析研究楔形鞋垫对膝关节载荷的影响

目的研究足底不同位置的楔形鞋垫对膝关节承载及运动特征的影响。方法利用三维动捕捉系统与测力台对10名健康成年女性受试者步态中的关节动力学变化特点进行分析研究。实验状态分为对照组和6组楔形鞋垫测试组。利用单因素方差分析评价楔形足底支撑对膝关节动力学参数的影响。结果相对于对照组,前内侧楔形鞋垫组显著减小了膝内翻力矩第1峰值(P<0.05);使用前外侧楔形鞋垫和外侧全长楔形鞋垫的两组显著减小了膝内翻力矩第2峰值(P<0.05,P<0.05)。结论使用楔形鞋垫可有效地减小站立相的膝关节内翻力矩,这将有助于设计适合的鞋垫以减轻由骨性关节炎所带来的疼痛。     

伤科手法治疗腰椎间盘突出症的运动学研究

为探索中医手法治疗腰椎间盘突出症的运动学规律和机制,选取上海交通大学附属瑞金医院魏氏伤科手法中的经典“悬足压膝”和“腰部提拉”手法动作作为研究对象。对10名健康青年男性施加手法动作,并通过三维运动捕捉系统采集手法作用时受试者的5次运动学数据,定义人体相对关节坐标系,并通过Visual3D软件建立人体三维运动模型。计算下肢髋关节、膝关节和踝关节的相对运动角度,并分解对应得到各关节的屈曲/伸展、外展/内收、轴向旋转运动,处理计算得到关节的平均运动角度和轨迹规律。统计各运动数据,分析运动的左右侧差异。结果表明,右侧髋关节的平均被动屈曲角度可达137.33°,被动伸展角度可达30.86°,这与解剖学上髋关节的被动最大角度以及其与膝关节位置相关的理论相一致,也验证了髋关节的极限屈曲/伸展角度与膝关节的位置有关,从而说明魏氏手法的运动学作用机理在于促进髋关节被动运动达到可达最大程度。同时发现,部分关节运动角度针对下肢惯用侧存在统计学上的左右侧差异(P<0.05)。该研究为手法的研究和定量评估提供新的研究方法。     

Influence of cadence,power output and hypoxia on the joint moment distribution during cycling

The purpose of this study was to use a hypoxic stress as a mean to disrupt the normal coordinative pattern during cycling. Seven male cyclists pedalled at three cadence (60, 80, 100 rpm) and three power output (150, 250, 350 W) conditions in normoxia and hypoxia (15% O2). Simultaneous measurements of pedal force, joint kinematics, % oxyhaemoglobin saturation, and minute ventilation were made for each riding condition. A conventional inverse dynamics approach was used to compute the joint moments of force at the hip, knee, and ankle. The relative contribution of the joint moments of force with respect to the total moment was computed for each subject and trial condition. Overall, the ankle contributed on average 21%, the knee 29% and the hip 50% of the total moment. This was not affected by the relative inspired oxygen concentration. Results showed that the relative ankle moment of force remained at 21% regardless of manipulation. The relative hip moment was reduced on average by 4% with increased cadence and increased on average by 4% with increased power output whereas the knee moment responded in the opposite direction. These results suggest that the coordinative pattern in cycling is a dominant characteristic of cycling biomechanics and remains robust even in the face of arterial hypoxemia.     

A 3D musculoskeletal model of the western lowland gorilla hind limb: moment arms and torque of the hip,knee and ankle

Three‐dimensional musculoskeletal models have become increasingly common for investigating muscle moment arms in studies of vertebrate locomotion. In this study we present the first musculoskeletal model of a western lowland gorilla hind limb. Moment arms of individual muscles around the hip, knee and ankle were compared with previously published data derived from the experimental tendon travel method. Considerable differences were found which we attribute to the different methodologies in this specific case. In this instance, we argue that our 3D model provides more accurate and reliable moment arm data than previously published data on the gorilla because our model incorporates more detailed consideration of the 3D geometry of muscles and the geometric constraints that exist on their lines‐of‐action about limb joints. Our new data have led us to revaluate the previous conclusion that muscle moment arms in the gorilla hind limb are optimised for locomotion with crouched or flexed limb postures. Furthermore, we found that bipedalism and terrestrial quadrupedalism coincided more regularly with higher moment arms and torque around the hip, knee and ankle than did vertical climbing. This indicates that the ability of a gorilla to walk bipedally is not restricted by musculoskeletal adaptations for quadrupedalism and vertical climbing, at least in terms of moment arms and torque about hind limb joints.     

下肢运动信息采集与运动仿真

目的 建立人体下肢3D模型与生物力学模型,进行运动学和动力学分析,搭建下肢控制平台为主动式下肢假肢和人体下肢助行器的控制研究提供理论依据。方法 利用VICON人体三维运动捕捉系统采集平地行走人体下肢髋、膝、踝运动信息。利用Solidworks建立人体下肢3D模型,进行下肢运动学分析。基于Matlab中Simulink的机械仿真模块（SimMechanics）建立人体下肢模型,进行动力学分析,产生运动信号。基于Quanser半实物仿真平台搭建控制模型,接收SimMechanics产生的运动控制信号,实现对双下肢运动平台的控制。结果 利用运动学分析得到各个关节的速度和加速度信号,利用动力学仿真得到各个关节的力矩信号,对建立的人体双下肢模型进行模拟仿真,通过仿真验证了模型的合理性,利用输出的信号对双下肢运动平台进行控制实现了平地行走功能。结论 建立的平台可以进行人体下肢运动学、动力学和控制方法的研究,为主动式假肢和人体下肢助行器的控制提供借鉴作用。     

The role of active forces and intersegmental dynamics in the control of limb trajectory over obstacles during locomotion in humans

The focus of this paper is to examine the contributions of active and passive forces in the control of limb trajectory over obstacles during locomotion. Kintetic analyses of the swing phase of locomotion were carried out to determine the power profiles at various joints and to parcel the joint moments into moments due to muscle action, gravitational force and motion-dependent terms. The analyses revealed that toe elevation over the obstacles was achieved primarily by flexing at the hip, knee and ankle joint. Power analyses showed that translational energy applied at the hip joint and rotational energy applied at the knee joint were modulated as functions of obstacle height. This demonstrates that increased hip and ankle joint flexion are achieved not through active muscle action but rather through passive forces induced by translational action at the hip (representing contribution by the stance limb muscles) and rotational action at the knee joint. Parcelling the joint moment terms into various components clearly shows how the nervous system exploits intersegmental dynamics to simplify control of limb elevation over obstacles and minimize energy costs.     

基于深度学习融合算法的无标记点步态分析系统

目的 以有标记点三维运动捕捉系统（MoCap）为金标准,基于双向长短时记忆（bi-lateral long short term memory,BiLSTM）递归神经网络和线性回归算法构建深度学习融合模型,减小深度传感器的系统误差,从而提高深度传感器下肢运动学分析的准确性。方法 招募10名健康男性大学生进行步态分析,应用MoCap系统和Kinect V2传感器同时采集数据。通过Cleveland Clinic及Kinect逆运动学模型分别计算下肢关节角度。以MoCap系统为目标,Kinect系统得到的角度为输入构建数据集,分别用BiLSTM算法和线性回归算法构建学习模型,得到系统误差修正后的下肢关节角度。使用留一交叉验证法评估模型的性能。采用多重相关系数（coefficient of multiple correlations,CMC）及均方根误差（root mean square error,RMSE）表示下肢关节角度波形曲线相似程度以及平均误差。结果 BiLSTM网络比线性回归算法更能够处理高度非线性的回归问题,尤其是在髋关节内收/外展、髋关节内旋/外旋和踝关节趾屈/背屈角度上。应用BiLSTM网络的误差修正算法显著降低Kinect的系统误差（RMSE<10°,其中髋关节RMSE<5°）,下肢角度波形呈现很好的一致性（除髋关节内旋/外旋角度外,CMC>0.7）。结论 本文开发的基于深度学习融合模型的无标记点步态分析系统可以准确评估下肢运动学参数、关节活动能力、步行功能等,在临床和家庭康复中具有广泛的应用前景。     

Biomechanical and reflex responses to joint perturbations during electrical stimulation of muscle: instrumentation and measurement techniques

A test device is developed to measure ankle joint compliance and muscle activity when the ankle is subjected to perturbations in angular position (or torque) from bias positions achieved volitionally or via electrical stimulation. The ankle measurement system uses a pivoting footplate and is operable with the subject sitting or supine. A companion platform for the knee is developed that uses a rotary arm and attached leg brace and is operable with the subject’s leg in the horizontal or vertical plane. The knee fixture’s pivoting arm can slide to account for the cam-like movement of the knee during rotation. The devices use similar hardware and share common instrumentation and control. Precise torque or position perturbations are delivered by a computer-controlled torque motor to the ankle or knee. Angular displacement, torque, acceleration, knee fixture moment arm and electromyographic data are collected on analogue tape and simultaneously digitised and stored. A special stimulator/recording amplifier permits the recording of electromyographic signals from the stimulated muscle. Experimental data indicate that the ankle and knee devices, operated horizontally, are purely inertial systems. Sample ankle and knee joint responses to perturbations are presented.     

Speed-related changes in hindlimb intersegmental dynamics during the swing phase of cat locomotion

Summary To determine speed-related changes in hindlimb motion that might account for the mutability of bifunctional (hip extensor/knee flexor) muscle activity during the E1 phase of swing, we studied hip and knee joint kinematics and kinetics during swing over a ten-fold increase in locomotor speed (0.35 to 3.5 m/s). Three cats were filmed (100 frames/s) while locomoting on a motorized treadmill; kinematics were analyzed for the entire step cycle and kinetics for the swing phase. During swing, angular excursions at the hip and knee joints were similar for walking and trotting, but hip flexion and extension were significantly less after the transition from trot to gallop, while knee-angle range of motion increased during gallop phases E1, E2, and E3. During swing, knee-extension velocity peaked early in E1 and increased linearly with speed, while hip-flexion velocity peaked late in the flexion (F) phase and also increased linearly, but decreased precipitously at the trotgallop transition and remained constant as speed of galloping increased. Muscle torque directions during E1, flexor at the knee and extensor at the hip, were consistent with the proposed role of bifunctional posterior thigh muscles to decelerate thigh and leg segments for paw contact. At the knee joint, muscle torque during E1 counteracted a large interactive torque due to leg angular acceleration; the magnitudes of both torques were speed related with maximal values at the fastest speed tested (3.5 m/s). At the hip joint, muscle torque during E1 also counteracted a large interactive torque due to leg angular acceleration; the magnitudes of these two torques were speed related during the walk and trot, and like hip flexion velocity, decreased at the trot-gallop transition. Our data on speed-related changes in hindlimb dynamics suggest that the E1 burst amplitude (and perhaps duration) of posterior thigh muscles will be speed related during the walk and trot. After the trot-gallop transition at about 2.5 m/s, the recruitment of these bifunctional muscles may decline due to the changes in hindlimb dynamics. Because activity of these muscles counteracts interactive torques primarily related to leg angular acceleration, we suggest that motion-related feedback decoding this action may be important for regulating recruitment during E1.     

Asymmetric knee loading at heel contact during walking in patients with unilateral knee replacement

Increased load on the knee joint by excessive levels of impact forces during initial contact has been suggested to lead to knee osteoarthritis (OA). Asymmetric loading after knee replacement may also relate to the development of OA in the contralateral limb, therefore this study investigated the heel strike transient vertical force and subsequent lower extremity kinematic, kinetic and spatio-temporal parameters during level walking between the operated and the contralateral limbs in patients 12 months following unilateral knee replacement. A six camera motion analysis system with a force plate was used to investigate the differences between limbs in the heel strike transient vertical GRF and its relative timing, and hip, knee and ankle angles and moments at initial contact, as well as spatio-temporal parameters during the stance phase of walking in 19 subjects with unilateral knee replacement. Paired t tests showed a significant difference in the contralateral limb relative to the operated limb in the heel strike transient magnitude (p=0.03), hip moment (p=0.01), knee moment (p=0.02) and ankle moment (p=0.03). No significant differences were found for the joint angles at heel contact or the spatio-temporal parameters (p>0.05). The heel strike transient magnitude was lower for the operated limb with no differences in the spatio-temporal parameters or the joint angles at initial contact between the limbs. Differences in the hip, knee and ankle moments were also found indicating an asymmetric loading of the impact force at initial contact on the lower extremity. The current findings may indicate an asymmetric loading on the knee joint and therefore may be clinically relevant in patients undergoing unilateral knee replacement.