青年人下肢主动和被动运动生物力学分析

目的运动疗法包括主动运动和被动运动两种方式,不同的方式对患者治疗效果不同。然而,在运动治疗过程中,患者对所进行的运动疗法存在理解和力度控制偏差,导致自主参与程度不合理,使实际的运动治疗方式与最初设想的不同。本研究以青年人为研究对象,旨在确立一种客观判断主动和被动运动差异的特征性指标,用以分析和评价青年患者的运动方式,进而矫正因自主参与程度不同导致的运动方式偏差。方法实验选取24名20~30周岁的健康青年人作为受试者(男、女各12人),实验内容为在脚踏车上先后进行主动和被动运动训练。运动速度为30 r/min,持续时间3 min。运动过程中,利用肌电测量系统记录受试者腓肠肌肌电信号、足底压力测量系统记录足底压力大小。结果不同运动方式下,腓肠肌肌电信号峰-峰值、积分肌电值和足底压力AD值[(最大值-最小值)/平均值]分界明显,具有显著性差异(P0.01);腓肠肌肌电信号方差值和足底压力最大值分界明显,具有显著性差异(P0.05)。上述结果不受性别差异的影响。结论不同运动方式下,肌电信号峰-峰值、积分肌电值、方差值和足底压力AD值、最大值分界明显,很可能可以作为判别青年人下肢主动运动和被动运动的客观指标,用以评价受试者自主参与运动治疗的程度。     

两种疲劳方案对落地时下肢运动学和冲击力时频特征的影响

目的比较两种疲劳方案对人体落地动作下肢关节运动学及冲击力时/频域特征的影响。方法选取15名优秀跑、跳类专项男性运动员,利用Vicon运动捕捉系统和Kistler三维测力台比较两种疲劳方案(恒速跑、折返跑+垂直纵跳)前后落地时矢、额状面运动学和地面反作用力(ground reaction force,GRF)时/频域特征。结果(1)两种疲劳方案均会造成髋、膝关节在矢状面上的角度减小、屈曲活动度增加,且采用跑+跳方案时踝关节屈曲活动度、膝关节最大屈曲角速度增加(P0.05),髋关节外展活动度以及髋、膝关节最大外展角速度增加(P0.05);(2)两种疲劳方案前后,冲击力时域特征均无显著差异;采用跑和跑+跳方案,分别在3.51、8.20 Hz及1.17、3.51、7.03 Hz下表现出GRF频谱振幅减小(P0.05)。结论两种疲劳方案均会导致下肢在受到落地冲击时更多采用屈曲着地方式,但跑+跳方案表现更明显且干预时间更短,从实验方法学角度更具优势。研究结果可为研究疲劳后的力特征提供进一步参考。     

皮质肌肉相干的影响因素及康复应用

皮质肌肉相干(CMC)是了解大脑皮质如何控制肌肉运动,以及评估大脑运动皮层与相关肌肉之间功能耦合的一种工具,在康复评估的相关研究中具有重要意义.从CMC的定义出发,概括了CMC在α、β与γ等3个主要频带的频率分布特征;从理论研究的角度,总结了作用力水平、年龄和病理状态等因素对CMC的影响;在CMC的应用研究方面,着重介...     

士兵负重单脚落地时膝关节生物力学特征以及与等速肌力的关系

目的 分析士兵负重单脚落地对膝关节产生的影响,并探讨与肌力的关系,为日常负重训练提供依据。方法 采用Vicon动作捕捉系统和AMTI测力台分别采集12名士兵学员不负重和负重15 kg从30 cm高度单脚落地时膝关节的运动学和动力学数据,同步采集大腿前后侧肌群表面肌电(surface electromyography, sEMG),并进行膝关节屈伸等速肌力测试。结果 与无负重相比,负重15 kg落地时膝关节屈曲角度和胫骨反作用力显著增加(P<0.05),股直肌、股内外侧肌和股二头肌sEMG最大值均显著增加(P<0.05),其余指标负重前后无显著差异(P>0.05)。伸膝峰值力矩与无负重单脚落地垂直地面反作用力呈显著负相关(P<0.05),其余指标无显著相关关系(P>0.05)。结论 负重15 kg单脚落地增加了膝关节屈曲角度和胫骨反作用力,大腿前后侧肌群的激活可缓解落地时的地面反作用力,肌力对于预防落地损伤具有一定作用。     

髋外展肌疲劳对不同性别人群单腿侧跳落地时神经肌肉控制的影响

目的 比较髋外展肌疲劳对不同性别人群单腿侧跳落地期间的姿势稳定性及其神经肌肉控制的影响。方法 比较20名男性和20名女性在髋外展肌疲劳干预前后进行单腿侧跳落地期间的压力中心(center of pressure, COP)、地面反作用力(ground reaction force, GRF)、下肢运动学、关节力矩、肌肉活动度等。结果 疲劳后,男性和女性COP在冠状面的最大位移和平均速度增加,髋关节外展峰值角度和踝关节外翻峰值角度增加,踝关节内翻峰值力矩增加。触地前200 ms,男性股直肌、股二头肌、胫前肌、腓骨长肌的激活小于女性;触地后200 ms,男性股二头肌激活小于女性。结论 髋外展肌疲劳导致冠状面姿势稳定性下降,髋、踝关节冠状面稳定性下降,可能增加关节损伤风险。不同性别人群的姿势调控策略存在差异,提示下肢关节损伤机制的性别差异值得进一步探究。     

衰老对侧向姿势干扰下神经肌肉反应的影响

目的应用表面肌电比较老年人和年轻人在侧向姿势干扰下的神经肌肉反应,为深入研究老年人侧向姿势控制能力下降的机制提供理论依据。方法利用足底水平干扰触发平台对14名老年人和14名年轻人进行突发侧向姿势干扰。表面肌电测试系统收集受试者左侧腓骨长肌、胫骨前肌、臀中肌和竖脊肌的肌电反应信号。结果对于突发侧向姿势干扰,老年人胫骨前肌、臀中肌和竖脊肌的神经肌肉反应时明显延迟,并且腓骨长肌、胫骨前肌和臀中肌肌电振幅达峰值的时间明显延长。结论应对突发姿势变化时,老年人踝关节、髋关节和躯干肌肉反应延迟以及踝关节和髋关节肌肉收缩效率不高,可能是老年人侧向姿势控制能力下降的主要原因。     

神经肌肉疲劳前后运动鞋对下肢落地冲击的生物力学影响

目的探讨神经肌肉疲劳前后缓冲型运动鞋对落地动作下肢冲击力特征,以及对运动学和动力学的影响。方法比较15名篮球专项运动员在疲劳干预前后,穿不同缓冲性能的运动鞋从60 cm高落地时的冲击力、负载率、下肢运动学、关节力矩、关节/下肢刚度等。结果疲劳前高缓冲鞋仅使后跟处负载率峰值减小,且到达后跟负载率时间比对照组更短。疲劳后高缓冲鞋显著减小后跟处冲击力峰值、负载率峰值和前脚掌的负载率峰值,同时显著延长到达冲击力和后跟负载率峰值的时间;穿高缓冲鞋使得踝关节触地角度、最小角度显著增大。在下肢刚度、踝关节峰值力矩和刚度方面两组鞋并未发现显著性的改变。结论在疲劳后,当人体下肢神经肌肉控制策略减弱时,高缓冲鞋能够有效地衰减冲击,进而有利于避免或减小潜在的冲击性运动损伤。     

局部低频振动刺激对手部运动功能的瞬时影响

目的 探讨局部低频振动刺激对手部控制能力、柔韧性、握力及肌肉兴奋程度的瞬时影响。方法 10位受试者以最大等长收缩握住手部振动器20 s,在此过程中随机给予12.5 Hz振动频率(振动组)或无振动刺激(对照组)。在介入前后分别进行手部控制能力、柔韧性、握力及手部肌肉兴奋程度等测验,并采用配对t检验比较前后测试的差异和各组变化率。结果 组内比较发现振动组在控制能力与柔韧性表现上进步显著(P＜0.05),对照组在握力与肌肉活化上出现显著下降(P＜0.05);组间变化率比较结果显示振动组在握力与肌肉兴奋程度变化率皆显著大于对照组(P＜0.05)。结论 局部低频振动刺激可瞬时提升手部控制能力与柔韧性表现,未来可运用于各种需要手部执行工作的相关人员。     

神经肌肉电刺激诱发的下肢运动疲劳信息检测与处理技术研究

限制神经肌肉电刺激(NMES)广泛应用的一个主要因素就是由其诱发的肌疲劳.设计NMES诱发下肢运动条件下的肌疲劳检测系统.分别进行膝关节角度的检测和表面肌电信号(sEMG)的频谱分析.研究表明,平均频率(MNF)、中值频率(MDF)及AR时变参数模型参量是评价NMES诱发肌疲劳的可靠指标,并且AR模型具有显著的高分辨灵敏度,最大变化率为90.23％,大于平均频率的43.82％和中值频率的55.49％,为NMES使用过程中诱发肌疲劳的准确评价和反馈寻找到一种可行的方法.     

基于肌电信号与肌肉形变信号的手语识别

针对手语手势识别问题,提出一种基于肌电信号与肌肉形变信号的手语识别架构。首先,设计信号采集系统;然后,采集肌电信号与肌肉形变信号,利用滤波及小波降噪等方法对原始数据进行降噪处理。采用基于能熵比的双门限端点检测法提取信号有效活动段;分别提取肌电信号以及肌肉形变信号特征,将所提取的信号特征融合组成特征向量;最后,采用基于网格搜索的支持向量机识别模型对所采集手语动作进行识别。信号融合后手语识别正确率达到97.2%,相对于仅采用肌电信号的手语识别方法,融入肌肉形变信号后识别率提高9.3%。结果表明,基于肌电信号和肌肉形变信号的手语识别框架对动态手语手势具有良好的识别效果。     

人体头低脚高仰卧时下肢被动运动对背部肌肉疲劳的影响

目的研究人体头低位状态下肢被动运动对背部主要肌肉肌电(electromyogram,EMG)活动性的影响。方法选取30名健康受试者,分析竖脊肌和斜方肌在不同头低位角度(0°、10°、20°、27°)下静止状态、120次/min和140次/min足部摆动模式和680次/min足部颤动模式下EMG变化趋势。结果在头低位静止状态时,4种头低位角度下中位频率(media frequency,MF)随角度增加均呈下降趋势;摆动模式下,4种头低位角度的MF值均小于静止状态,且当摆动速度为120次/min时,MF值随角度增加而减小;速度为140次/min时,MF值无规律性变化。颤动模式下,MF值随头低位角度增大而增大,且均大于静止状态。结论静止状态下,肌肉疲劳程度随头低位角度增加而增加;颤动模式下应选择较小的头低位角度可更好达到锻炼治疗效果,摆动模式下可选择较大的头低位角度有助于较好达到锻炼治疗效果。此外,为避免肌肉过度疲劳造成劳损,摆动速度应不大于120次/min。     

新式屈髋肌力训练机在轻重阻力下对下肢肌电与运动范围的影响

目的探讨新式屈髋肌力训练机在轻、重阻力情况下对下肢肌肉兴奋程度与运动范围的影响。方法 6位志愿者在屈髋肌力训练机台上,随机在轻或重阻力条件下进行连续30次的上提与下摆动作,并同时采集运动过程中的肌肉兴奋程度与下肢运动范围。结果肌肉兴奋程度方面,在连续30次动作过程中,重阻力在腹直肌、屈髋肌、臀大肌、股直肌和股二头肌的兴奋程度皆显著高于轻阻力(P<0.05);重阻力在腹直肌、屈髋肌和股直肌后3次的兴奋程度皆显著高于前3次(P<0.05);轻阻力情况下,只有竖脊肌以及股直肌最后3次的兴奋程度显著高于前3次(P<0.05)。运动范围方面,重阻力情况下的动作范围与下摆角度显著小于轻阻力(P<0.05)。结论新式屈髋肌力训练机无论是在轻或重阻力条件下,都能在髋关节合理的活动范围内刺激屈与伸髋主动肌群以及周边协同肌群来完成动作,特别是相对较重阻力的条件下。     

Changes in intra-abdominal pressure,trunk muscle activation and force during isokinetic lifting and lowering

Intra-abdominal pressure (IAP), force and electromyographic (EMG) activity from the abdominal (intra-muscular) and trunk extensor (surface) muscles were measured in seven male subjects during maximal and sub-maximal sagittal lifting and lowering with straight arms and legs. An isokinetic dynamometer was used to provide five constant velocities (0.12–0.96 m·s^–1) of lifting (pulling against the resistance of the motor) and lowering (resisting the downward pull of the motor). For the maximal efforts, position-specific lowering force was greater than lifting force at each respective velocity. In contrast, corresponding IAPs during lowering were less than those during lifting. Highest mean force occurred during slow lowering (1547 N at 0.24 m·s^–1) while highest IAP occurred during the fastest lifts (17.8 kPa at 0.48–0.96 m·s^–1). Among the abdominal muscles, the highest level of activity and the best correlation to variations in IAP (r=0.970 over velocities) was demonstrated by the transversus abdominis muscle. At each velocity the EMG activity of the primary trunk and hip extensors was less during lowering (eccentric muscle action) than lifting (concentric muscle action) despite higher levels of force (r between –0.896 and –0.851). Sub-maximal efforts resulted in IAP increasing linearly with increasing lifting or lowering force (r=0.918 and 0.882, respectively). However, at any given force IAP was less during lowering than lifting. This difference was negated if force and IAP were expressed relative to their respective lifting and lowering maxima. It appears that the IAP increase primarily accomplished by the activation of the transversus abdominis muscle can have the dual function of stabilising the trunk and reducing compression forces in the lumbar spine via its extensor moment. The neural mechanisms involved in sensing and regulating both IAP and trunk extensor activity in relation to the type of muscle action, velocity and effort during the maximal and sub-maximal loading tasks are unknown.     

Surface muscle pressure as a measure of active and passive behavior of muscles during gait

While surface electromyography (SEMG) can accurately register electrical activity of muscles during gait, there are no methods to estimate muscular force non-invasively. To better understand the mechanical behavior of muscle, we evaluated surface muscle pressure (SMP) in conjunction with SEMG. Changes in anterior thigh radial pressure during isometric contractions and gait were registered by pressure sensors on the limb. During isometric knee extensions by a single subject, SMP waveforms correlated well with SEMG (r=0.97), and SEMG onsets preceded those of SMP by 35-40 ms. SMP and SEMG signals were simultaneously recorded from the quadriceps of 10 healthy subjects during gait at speeds of 0.4, 0.8, 1.1, 1.4 and 2.2m/s. Muscle activity onset and cessation times were objectively determined for both modalities, and results showed high intra-class correlations. SMP waveforms were highly consistent from stride to stride, while SEMG waveforms varied widely. SEMG waveforms were typically brief, while SMP waveforms tended to be biphasic and outlasted the SEMG by approximately 40% of gait cycle at all speeds. These results are consistent with mechanical models of muscle, and demonstrate the use of SMP to estimate the timing of knee extensor muscle stiffness during gait.     

评估肌肉疲劳的中枢和外周起源

疲劳是很多内科及神经疾患的常见表现,理解这些疾病肌肉疲劳的中枢或者外周起源对制定针对性的肌肉疲劳治疗措施具有重要指导意义。综述肌肉疲劳发生的中枢因素(包括脊髓水平和激素上水平所有可以导致运动神经元兴奋性下降的因素)、外周因素(包括神经肌肉的传播、肌肉动作电位的扩散、兴奋-收缩偶联),并讨论采用直接(最大自主收缩、抽搐力)和间接(抽搐叠加、肌电图、运动皮质刺激)的检测方法评估肌肉疲劳的中枢和外周起源。     

一指禅推法不同作用力下上肢肌群运动方式及肌电信号

目的观察不同手法力量下一指禅推法上肢肌电信号特征,找出手法操作关键技术上肢肌群协同运动方式。方法采集专家组、熟练组和初学组手法肌电信号数据。每位测试者按手法力量分轻、中、重3种类型操作,选择连续稳定的数据采用MyoResearch软件进行分析。结果上肢各测试肌群肌电积分(iEMG)比较有显著差异(P<0.05);不同手法力量肌群iEMG比值比较,专家组和熟练组无显著差异(P>0.05),比值前3位为尺侧腕屈肌群、三角肌、桡侧伸肌群;手法核心主动肌群参与运动方式基本一致。初学组在不同手法力量下iEMG比值前3位肌肉群各不相同,差异较明显。专家组、熟练组和初学组之间协同收缩率比较差异均显著(P<0.01),初学组协同收缩率最大,专家组协同收缩率最小,且协同收缩率随手法力量增加逐渐下降。6 min操作三角肌肉中位频率斜率比较,专家组测试者耐疲劳度较好。结论专家组和熟练组手法肌电信号有共同特征,存在手法操作的核心肌群。上肢核心肌群运动方式具有规律性,并且iEMG比值、中位频率斜率、协同收缩率等指标可作为评价手法持久性、均匀性,以及施力方式是否规范的参考标准。     

Force path curvature and conserved features of muscle activation

This study examined the patterns of muscle activity that subserve the production of dynamic isometric forces in various directions. The isometric condition provided a test for basic features of neuromuscular control, since the task was analogous to reaching movement, but the behavior was not necessarily shaped by the anisotropy of inertial and viscoelastic resistance to movement. Electromyographic (EMG) activity was simultaneously recorded from nine elbow and/or shoulder muscles, and force pulses, steps, and ramps were monitored using a transducer fixed to the constrained wrists of human subjects. The force responses were produced by activating shoulder and elbow muscles; response direction was controlled by the relative intensity of activity in muscles with different mechanical actions. The primary objective was to characterize the EMG temporal pattern. Ideally, synchronous patterns of phasic muscle activation (and synchronous dynamic elbow and shoulder torques) would result in a straight force path; asynchronous muscle activation could result in substantial force path curvature. For both pulses and steps, asynchronous muscle activation was observed and was accompanied by substantial force path curvature. A second objective was to compare phasic and tonic EMG activity. The spatial tuning of EMG intensity was similar for the phasic and tonic activities of each muscle and also similar to the spatial tuning of tonic activity in a previous study where the arm was stationary but unconstrained.     

Influence of muscle activation dynamics on reaction time in the elderly

The aim of this investigation was to determine whether age-related changes in the dynamics of muscle activation were, in part, responsible for longer reaction times (RT) in the elderly. A group of 12 young (mean age, 20.6 years) and 12 elderly (mean age, 64.3 years) women performed a series of ballistic forearm supination movements in response to an auditory stimulus while using a simple reaction time test. Surface electromyographic waveforms from biceps brachii (agonist) and pronator teres (antagonist) muscles were recorded, together with the angle-time curves representing the motion of the forearm, on to an IBM compatible microcomputer. The results showed that an age-related increase (P<0.05) in motor reaction time (MRT) contributed to longer RT in the elderly. In addition, the longer (P<0.05) MRTs in the elderly were associated with a significantly slower rate (P<0.05) of biceps brachii muscle activation and a significantly increased proportion (P<0.05) of the initial biceps brachii muscle burst required to initiate the movement. This data suggested that an important part of the slowing of motor behaviour, commonly observed with increasing age, may be due to either decreases in the ability of aged skeletal muscle to rapidly generate tension or to a reduction in motor drive.     

静态姿势下均匀负重和非负重时躯干和表面肌电活动

目的观察躯干均匀负重和非负重状态下静态前屈和后伸时腰背部、腹部及臀中肌的肌电活动规律和运动学特征。方法 6位正常健康的男性受试者直腿站立于特殊设计的试验框架和平台内做静态前屈和后伸的负重和非负重动作,每次试验持续4 s,重复3次。动作时,记录双侧腰臀部的10块肌肉:腹直肌、腹外斜肌、竖脊肌、多裂肌、臀中肌的肌电活动,以及三维角度运动轨迹和足底力系。计算标准化肌电、腰部躯干角和足底中心压力的位移。将所得数据作常规的统计分析。结果负重和非负重前屈时,都是背侧肌活动较大(10.47～16.94)。非负重后伸时,腹侧肌活动也较大;负重后,背侧肌(3.70～17.95)和臀中肌(6.64～11.52)活动增加,腹肌活动减少(10.66～4.18)。后伸时,躯干的闪动次数随负重增加而增多,在3D角上增加1.55次;负重后,足底中心压力向前后的移动多于侧方移动,前屈的前后方移动(14.60)多于后伸的移动(7.65)。结论后伸状态增加了背侧肌的活动,而且多裂肌更明显;同时,腰部角位移度和闪动次数增加,特别在后伸提重时更为显著。