基于表面肌电分析老年人负重跨障行走跌倒风险

目的研究老年人在手部不同负重分布条件下跨越障碍物时导致跌倒风险性增加的因素,并探讨预防老年人在负重跨障时跌倒的步态策略。方法 12名老年人和12名青年人(对照组)以日常行走步速在不同负重分布方式下进行跨越障碍物和无障碍物行走任务,采集股外侧肌、股直肌和股内侧肌双侧的表面肌电信号,进行平均肌电值分析对比,同时记录受试者跨越障碍时触碰障碍物的情况。结果年龄、负重及跨障因素均对老年人下肢肌肉的活动水平产生显著影响。1 152次跨障试验中共发生9次触障事件。另外,老年人和青年人在完成负重和跨障任务时右股内侧肌的肌肉贡献量最大。结论老年人在负重物均匀分布下利用腿部优势侧率先跨障的情况下跌倒的风险性最低。研究结果为系统评估老年人跌倒风险提供参考,对老年人针对性下肢运动锻炼或康复训练具有一定的指导意义。     

步态康复机器人评价正常老年人步态的性别差异

背景：在国内采用步态康复机器人对正常老年人的步态进行评定的研究较少,且无明确结论。 目的：采用步态康复机器人对正常老年人的肌力、关节活动度、痉挛状态等指标进行评定,了解老年人步态的特点。 方法：选取健康老年人30名,男15名,女15名,年龄(62.40±1.58)岁。利用步态康复机器人的评估工具L-FORCE, L-STIFF和 L-ROM测试受试者的肌力、痉挛状态和关节活动度。 结果与结论：老年人L-FORCE测试结果显示,双侧髋屈肌力和双侧膝屈伸肌力在健康老年人不同性别间差异有显著性意义(P < 0.05)。老年人L-STIFF测试结果显示,60 (°)/s左髋伸、120 (°)/s左髋屈伸痉挛状态在不同性别间差异有显著性意义(P < 0.05)。老年人L-ROM测试结果显示,健康老年人行走时关节活动度不存在性别差异(P > 0.05)。提示老年男性下肢肌力大于女性;老年男性L-STIFF测试结果高于老年女性,提示治疗师在对患者进行L-STIFF评价时要考虑性别因素;健康老年人关节活动度不存在性别差异。     

人体背部负重对于步态特征的影响及相应补偿策略的实验研究

人体背部负重量大小对步态特征的影响及相应补偿策略的研究对于自主式两足步行机器人的设计和平衡控制以及军人体能训练均有重要意义。从实验的角度对受试者分别背部负重6kg、12kg和25kg时的步态特征和补偿策略进行了研究。结果表明：人体背部负重后会引起步态特征的明显变化，这种差异主要表现在髋关节、膝关节以及上躯干的摆动角位移变化。负重后，人体的平均步速明显降低，但其步长的变化并不明显。人体对于负重的响应特征与受试者的肌肉强度是密切相关的。为有效补偿背部负重所产生的影响，人体利用多关节协调运动来进行补偿。但各个关节的贡献不同，其补偿主要由髋关节、膝关节以及上躯干的摆动来完成，踝关节的贡献相对较小。背部负重后总质心向前的调整主要是由上躯干的向前倾斜来实现。负重量越大，上躯干向前倾斜的平均角位移越大。为减少负重后的冲击对关节的损伤，脚跟触地时，可利用髋关节和膝关节的弯曲刚度来吸收冲击。     

负重对行军士兵下肢步态特征的影响

目的评定负重行军对下肢步态产生的影响。方法采用随机交互设计,15名健康男性受试者进行4次步行,作训着装0、7.5、27、50kg,分别采用Vicon运动捕捉系统和AMTI测力台检测髋部、膝部和踝部运动学参数的变化。结果随着负重增加,周期性步频相对增加,步幅减小,基本上维持在恒定速度;左右髋关节屈角峰值、外旋角度峰值以及左右膝关节内收峰值受到影响较为明显,但关节运动幅度能够维持。左踝关节内翻角度峰值以及右踝关节外翻角度峰值同样受到影响;下肢左右膝、踝关节的力和力矩增加。结论在既定负荷范围内,负重增加,整体上下肢关节变化较为稳定,但下肢负荷增加,可潜在增加下肢损伤的风险。     

老年人上下楼梯的步态特征以及下肢关节运动功能特点

目的 探讨老年人上下楼梯的步态特征以及下肢关节运动的力学性能。 方法 通过17名青年人、15名老年人自然速度上下5个台阶的楼梯测试与分析,并结合红外高速运动捕捉系统和三维测力台获取步态参数、下肢关节角度以及地面反作用力,通过逆向动力学方法计算关节力矩和功率,采取独立样本 t 检验分析年龄对上述参数的影响。 结果 与青年人相比,老年人上下楼梯步态周期较长,步速和步频则明显较低(P<0. 05);同时,老年人上下楼梯支撑相和摆动相分别明显延长和缩短(P<0. 05)。 不论是青年人还是老年人,上下楼梯过程中下肢关节角度、力矩和功率的变化趋势较为一致。 但老年人上楼主要是通过踝、膝关节功率的产生来维持,而青年人则是通过近端肢体的能量,特别动用了较多的膝关节功率。 下楼过程中的能量吸收,两者皆是以膝关节为主。 结论 随着年龄的增长,下肢机能下降和肌力不足,老年人害怕在上下楼梯时发生跌倒,试图通过减少摆动时间来弥补身体的不稳定。 研究结果为临床上老年患者群体的康复管理以及预测跌倒的功能性评估提供参考。     

不同速度下正常老年人下肢关节的角度参数

背景：目前国内主要采用步态分析仪测量患者步行时的关节角度,但是在每一个康复治疗时期进行这些测量非常耗费时间。利用Lokomat步态康复机器人则可以在患者训练过程中对患者的关节角度、肌力等参数进行实时记录,省时省力。 目的：采用步态康复机器人Lokomat测定正常老年人不同速度下的下肢关节角度参数。 方法：选取健康老年人30名,男15名,女15名,年龄60~64(62.40±1.58)岁。利用步态康复机器人评估工具,在减重40%,引导力60%,速度1.6,1.8,2.0 km/h状态下对正常老年人的下肢关节角度参数进行记录。 结果与结论：老年人关节角度参数动态指标测试结果显示,在速度1.6 km/h状态下左髋关节最大伸展角度,在速度2.0 km/h状态下左、右髋关节最大屈曲角度,男女组间差异有显著性意义(P < 0.05)。老年人不同速度下髋膝关节角度测试结果显示,老年人左右膝关节最大伸展角度在步行速度1.6 km/h与1.8 km/h,1.6 km/h与2.0 km/h,1.8 km/h与2.0 km/h相比差异有显著性意义(P < 0.05)。结果可见不同速度下髋关节最大屈曲角度男性大于女性,治疗师在进行Lokomat步态康复训练时应根据患者的性别差异,调整髋膝关节角度和训练模式。随着步行速度的增加老年人髋膝关节屈曲角度增加,伸展角度减小,治疗师应根据步速的增减适当调节髋膝关节活动度,增强患者腿部运动与机器人外骨骼式机械腿的配合,提高患者的训练效果。     

单侧全膝置换前后女性患者步态特征分析

目的研究单侧全膝置换(total knee arthroplasty,TKA)手术前后女性患者双侧下肢步态特征。方法基于三维步态采集和独立样本t检验,对比10例女性患者单侧TKA手术前后双侧下肢的步态参数,并分别与对照组10例健康志愿者比较,分析女性患者双侧步态差异及分别与正常步态的差异。结果术前患者非手术侧支撑期、膝关节内收角度峰值、冠状面活动度和屈曲力矩峰值显著大于手术侧(P0.05),术后无统计学差异;与对照组比较,术前患者步速、步长较小,双支撑期较长,手术侧膝关节伸展和内收角度峰值、冠状面活动度、屈曲和外展力矩峰值较小,内收力矩峰值较大,非手术侧膝关节伸展角度峰值较小,屈曲和内收力矩峰值较大,均存在统计学差异(P0.05),术后双侧膝关节伸展角度和内收力矩峰值与对照组的显著差异持续存在(P0.05)。结论单侧TKA能减轻患者疼痛,改善双侧下肢步态偏差,但与对照步态仍存在差异。患者肌力及本体感受等关节功能尚未恢复,病理步态与不良体态仍然存在,应加强患侧肌力锻炼及步态矫正训练。女性患者术后同时应注意步速控制,以防膝关节受力增加。     

基于实时步态分析的行走辅助外骨骼机器人系统

面向因病痛或自然衰老等原因腿部运动功能受到轻度影响的患者或老年人,本文提出了一种可穿戴外骨骼机器人系统,通过体重支撑的方式减轻双腿在行走过程中对髋、膝、踝关节和腿部肌肉的负载,以实现行走辅助的功能。考虑到使用人群的心理诉求和病症特点,有别于固定式或跟随式康复机器人上配有的减重系统,本文提出的外骨骼机器人结构美观,轻巧便携。系统通过足底压力传感器实时对使用者的步态进行分析,通过步态相的划分,针对各步态相提出不同的控制策略。通过座椅上的压力传感器实时监测外骨骼提供支撑力度的大小,且驱动控制使用比例-积分-微分(PID)控制技术进行力矩控制。机器人系统总重12.5 kg,站立时平均辅助支撑约10 kg,行走中平均辅助支撑约3 kg,起到了一定的体重支撑效果,减轻了行走和站立时对下肢的压力。     

人体负重行走的生物力学研究及前景

背景：人体背部负重行走时若背负重物过重或长时间地承担质量,容易导致一系列的损伤问题,目前有关人体负重行走状态下的生物力学研究较少。 目的：综述人体负重行走的步态参数变化、足-地反作用力变化、压力传感器及肌电的应用。 方法：由第一作者检索2005/2010 PubMed数据库及中国知网数据库有关负重、行走、背包方面的文章。英文检索词为“gait,load carriage, backpack”,中文检索词为“负重行走、背包、步态”。 结果与结论：目前对于负重行走的研究：①在研究指标上,各种指标比较单一,综合研究还不够。②在研究对象上,针对青年人群和儿童的相关研究比较多,有关士兵负重行军的研究相对较少。③在研究内容上,针对负重行走的步态研究居多,背包商业化测试较多,对产生负重损伤的生物力学机制探讨,以及足底压力变化上研究较少,对相关鞋类产品的生物力学测试关注不够。④在研究结果上,一些研究结果产生相互矛盾的结论,致使负重行走对人体步态影响的确切机制仍旧模糊不清。     

基于有限元方法的全髋关节假体个体化选型分析

目的 研究ISO 7206标准对全髋关节置换术临床应用的指导意义。方法 建立肌骨数值模型,对正常行走步态进行仿真,以获得下肢的运动学和动力学参数;建立对应的全髋关节假体有限元模型,应用步态载荷进行计算,并对比ISO标准的有限元模型计算结果。结果 正常行走步态下,髋关节力分别在20%和54%步态周期出现峰值,以此作为有限元计算的步态载荷,得到20%步态周期时假体应力最大;松动模型中假体柄上最大应力大于无松动模型中假体柄上最大应力,且应力分布趋势存在差异;分析对比ISO测试和不同体重人体步态载荷下的假体最大应力,得到ISO测试中最大应力水平对应108~142 kg体重载荷下的假体最大应力。结论ISO测试中合格的假体可满足100 kg体重人体正常步态下的强度要求。     

Alternate leg movement amplifies locomotor-like muscle activity in spinal cord injured persons

It is now well recognized that muscle activity can be induced even in the paralyzed lower limb muscles of persons with spinal cord injury (SCI) by imposing locomotion-like movements on both of their legs. Although the significant role of the afferent input related to hip joint movement and body load has been emphasized considerably in previous studies, the contribution of the "alternate" leg movement pattern has not been fully investigated. This study was designed to investigate to what extent the alternate leg movement influenced this "locomotor-like" muscle activity. The knee-locked leg swing movement was imposed on 10 complete SCI subjects using a gait training apparatus. The following three different experimental conditions were adopted: 1) bilateral alternate leg movement, 2) unilateral leg movement, and 3) bilateral synchronous (in-phase) leg movement. In all experimental conditions, the passive leg movement induced EMG activity in the soleus and medial head of the gastrocnemius muscles in all SCI subjects and in the biceps femoris muscle in 8 of 10 SCI subjects. On the other hand, the EMG activity was not observed in the tibialis anterior and rectus femoris muscles. The EMG level of these activated muscles, as quantified by integrating the rectified EMG activity recorded from the right leg, was significantly larger for bilateral alternate leg movement than for unilateral and bilateral synchronous movements, although the right hip and ankle joint movements were identical in all experimental conditions. In addition, the difference in the pattern of the load applied to the leg among conditions was unable to explain the enhancement of EMG activity in the bilateral alternate leg movement condition. These results suggest that the sensory information generated by alternate leg movements plays a substantial role in amplifying the induced locomotor-like muscle activity in the lower limbs.     

坡面步行中青年女性下肢关节角及肌肉激活度

目的通过定量分析关节角及主要肌肉激活度的变化来说明步行速度和路面坡度对下肢运动的影响。方法首先按由慢到快选择了共5种步行速度,由低到高选择3种坡度,并利用运动捕捉系统对15各青年女性的步态进行测量,同时对影响下肢运动的8块主要肌肉的肌电信号进行了采集。然后通过计算分析获得她们在不同步行速度和路面坡度下髋、膝及踝关节矢状面的关节角度变化的均值,从测量数据中寻找出一个最接近这个均值曲线的研究对象。结果计算获得了该研究对象不同步行速度和路面坡度下踝关节、膝关节及髋关节在一个步态周期内的矢状面关节角的变化曲线以及主要肌肉的激活度变化曲线。结论每个步态周期内,关节角及肌肉激活度在5种不同速度下的变化很小;而在3种不同路面坡度下的变化仅趋势基本一致,峰值的差异却非常明显。     

Age-related differences in postural control in humans in response to a sudden deceleration generated by postural disturbance

Age-related differences in postural control in response to a relatively large deceleration resulting from postural disturbance were investigated in eight normal elderly men (age range 67–72 years) and eight young men as controls (age range 19–22 years) using a moving platform. Data were obtained for the hip, knee and ankle angles, position of the centre of foot pressure (CFP), head acceleration, and muscle activity of the leg muscles. The elderly subjects had slower and larger ankle and hip joint movements, and CFP displacement in response to the disturbance compared to the young controls. The elderly subjects also had a delayed occurrence, and greater magnitude of peak acceleration of head rotation than did the young subjects. For the elderly subjects, the CFP was closely related to angular changes in the hip joint movement, but not to those of the ankle and knee joint movements. For the young subjects, on the other hand, the CFP was significantly correlated with angular change in the ankle joint. Co-contraction of the tibialis anterior and gastrocnemius muscles was observed in the elderly subjects. The results indicated that a movement pattern for postural correction in the elderly adults was different from that of the young adults. The elderly relied more on hip movements while the young controls relied on ankle movements to control postural stability. Electronic Publication     

Single joint perturbation during gait: neuronal control of movement trajectory

The aim of this study was to investigate the effect of single joint displacement on the pattern of leg muscle electromyographic (EMG) activity during locomotion. For the first time, unilateral rotational hip or knee joint displacements were applied by a driven orthotic device at three phases of swing during locomotion on a treadmill. The response pattern of bilateral leg muscle activation with respect to the timing and selection of muscles was almost identical for displacements of upper (hip joint) or lower (knee joint) leg. The leg muscle EMG responses were much stronger when the displacement was directed against the physiological movement trajectory, compared with when the displacement was reinforcing, especially during mid swing. It is suggested that these response patterns are designed to restore physiological movement trajectory rather than to correct a single joint position. Displacements released at initial or terminal swing, assisting or resisting the physiological movement trajectory, were followed by similar and rather unspecific response patterns. This was interpreted as being directed to stabilise body equilibrium.     

Motor patterns of a fast voluntary postural task in man: trunk extension in standing

The co-ordination between muscles controlling the primary movement and associated postural adjustments during fast trunk extension movements was studied in six male subjects. Myoelectrical activity (EMG) was recorded from antagonistic muscle pairs at the trunk, hip, knee and ankle. Horizontal displacements of the upper trunk, hip and knee were recorded with an opto-electronic system (Selspot). A backward displacement of the trunk was accompanied by a forward displacement of the hip and knee. In general, the trunk started to move 30 ms before the hip and knee. Muscle activity first appeared in the ankle extensors (soleus/gastrocnemius) up to 150 ms prior to onset of prime mover muscles (trunk extensor, erector spinae; and hip extensors/knee flexors, hamstrings). This pre-activation was seldom followed by any detectable ankle joint movement. Prime mover muscles were activated simultaneously followed by the hip extensor gluteus maximus. Time to activation of muscles braking the movement (rectus abdominis, rectus femoris and vastus lateralis) was correlated with the amplitude of the primary movement (r = 0.63 0.75, P less than 0.01). Onset of activity in vastus lateralis was highly correlated with the amplitude of the forward displacement of the knee (r = 0.93, P less than 0.01). An associated postural adjustment appeared as an ankle flexion accompanied by activity in the ankle flexor tibialis anterior, and often also in the ankle extensors. This co-activation of antagonistic ankle muscles can under certain conditions have interesting functional implications for the control of posture.     

Identification of the plant for upright stance in humans: multiple movement patterns from a single neural strategy

We determined properties of the plant during human upright stance using a closed-loop system identification method originally applied to human postural control by another group. To identify the plant, which was operationally defined as the mapping from muscle activation (rectified EMG signals) to body segment angles, we rotated the visual scene about the axis through the subject's ankles using a sum-of-sines stimulus signal. Because EMG signals from ankle muscles and from hip and lower trunk muscles showed similar responses to the visual perturbation across frequency, we combined EMG signals from all recorded muscles into a single plant input. Body kinematics were described by the trunk and leg angles in the sagittal plane. The phase responses of both angles to visual scene angle were similar at low frequencies and approached a difference of approximately 150 degrees at higher frequencies. Therefore we considered leg and trunk angles as separate plant outputs. We modeled the plant with a two-joint (ankle and hip) model of the body, a second-order low-pass filter from EMG activity to active joint torques, and intrinsic stiffness and damping at both joints. The results indicated that the in-phase (ankle) pattern was neurally generated, whereas the out-of-phase pattern was caused by plant dynamics. Thus a single neural strategy leads to multiple kinematic patterns. Moreover, estimated intrinsic stiffness in the model was insufficient to stabilize the plant.     

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。     

Fast voluntary trunk flexion movements in standing: motor patterns

The electromyographical (EMG) activity was studied during voluntary flexion movements of the trunk in erect standing man. The movements were performed at maximal velocity with successively increasing amplitude to cover the whole range of motion. The EMG activity was recorded from agonist-antagonist pairs of muscles at the ankle, knee, hip and trunk. The angular displacements at the corresponding joints were recorded using a Selspot optoelectronic system. The duration of initiating activity in prime movers (rectus abdominis and rectus femoris) as well as time to onset of activity in muscles braking the primary movement (erector spinae, gluteus maximus and hamstrings) were highly correlated with amplitude, duration, peak velocity and time to peak velocity of the movement (r = 0.59-0.91). The corresponding correlations for peak acceleration and deceleration of the movement were low (r = 0.03-0.38), indicating that acceleration and deceleration of a movement was not coded in the temporal aspects of the EMG. Onset of activity in rectus abdominis and rectus femoris as well as an early appearing burst of activity in vastus lateralis were invariant in relation to start of movement over the whole movement range. In the initial phase of a fast trunk flexion, activity in tibialis anterior appeared successively earlier with increasing movement amplitude. This resulted in a changed order of activation for the muscles from proximal to distal (rectus abdominis first) to distal to proximal (tibialis anterior first). Two different forms of associated postural adjustments are present during a fast trunk flexion, one early fast knee flexion and a later slower angle extension. Prior to knee flexion, no activity was recorded from muscles flexing at the knee implying that some other force must create a flexing torque around the knee. It is suggested that activity in rectus abdominis initiating the primary movement also initiates knee flexion through the upward pulling of pelvis. This would be possible since rectus femoris stabilizes the pelvis in relation to the leg, allowing the force in rectus abdominis to be transmitted below the hip joint and act extending around the ankle joint. However, when tibialis anterior is activated it stabilizes the shank which in turn will cause a knee flexion controlled by a lengthening contraction in vastus lateralis. During the subsequent ankle extension activity appears in lateral gastrocnemius and soleus causing the associated postural adjustment at the ankle. It can be concluded that activation of postural muscles prior to prime mover muscles is not always necessary.(ABSTRACT TRUNCATED AT 400 WORDS)     

Adaptive control for backward quadrupedal walking. II. Hindlimb muscle synergies

1. To compare the basic hindlimb synergies for backward (BWD) and forward (FWD) walking, electromyograms (EMG) were recorded from selected flexor and extensor muscles of the hip, knee, and ankle joints from four cats trained to perform both forms of walking at a moderate walking speed (0.6 m/s). For each muscle, EMG measurements included burst duration, burst latencies referenced to the time of paw contact or paw off, and integrated burst amplitudes. To relate patterns of muscle activity to various phases of the step cycle, EMG records were synchronized with kinematic data obtained by digitizing high-speed ciné film. 2. Hindlimb EMG data indicate that BWD walking in the cat was characterized by reciprocal flexor and extensor synergies similar to those for FWD walking, with flexors active during swing and extensors active during stance. Although the underlying synergies were similar, temporal parameters (burst latencies and durations) and amplitude levels for specific muscles were different for BWD and FWD walking. 3. For both directions, iliopsoas (IP) and semitendinosus (ST) were active as the hip and knee joints flexed at the onset of swing. For BWD walking, IP activity decreased early, and ST activity continued as the hip extended and the knee flexed. For FWD walking, in contrast, ST activity ceased early, and IP activity continued as the hip flexed and the knee extended. For both directions, tibialis anterior (TA) was active throughout swing as the ankle flexed and then extended. A second ST burst occurred at the end of swing for FWD walking as hip flexion and knee extension slowed for paw contact. 4. For both directions, knee extensor (vastus lateralis, VL) activity began at paw contact. Ankle extensor (lateral gastrocnemius, LG) activity began during midswing for BWD walking but just before paw contact for FWD walking. At the ankle joint, flexion during the E2 phase (yield) of stance was minimal or absent for BWD walking, and ankle extension during BWD stance was accompanied by a ramp increase in LG-EMG activity. At the knee joint, the yield was also small (or absent) for BWD walking, and increased VL-EMG amplitudes were associated with the increased range of knee extension for BWD stance. 5. Although the uniarticular hip extensor (anterior biceps femoris, ABF) was active during stance for both directions, the hip flexed during BWD stance and extended during FWD stance.(ABSTRACT TRUNCATED AT 400 WORDS)