重复性搬举作业所致背部肌肉疲劳的表面肌电信号分析

目的　应用表面肌电信号 (SEMG)技术对重复性搬举所致的竖脊肌疲劳进行评价。方法　通过对 13名自愿者 10 0次搬举 8kg负荷至腰部高度的EMG波幅分析和搬举前后 2次静态实验EMG信号快速傅立叶转换 (FFT)后的频谱变化分析对竖脊肌疲劳进行评估。结果　 10 0次动态搬举过程中 ,随着时间的延长 ,EMG平均波幅逐渐上升 ,T10右竖脊肌和L3左竖脊肌平均波幅的差异有显著性 (P <0 .0 5、P <0 .0 1) ;而T10左竖脊肌和L3右竖脊肌的差异无显著性 (P >0 .0 5 )。中频截距在T10右竖脊肌、T10左竖脊肌、L3右竖脊肌、L3左竖脊肌均有下降。T10右竖脊肌中频截距下降了2 .0 % ,与搬举前的差异无显著性 (P >0 .0 5 ) ,T10左竖脊肌、L3右竖脊肌和L3左竖脊肌分别下降了10 .9%、2 9.9%、2 7.9% ,与搬举前的差异均有显著性 (P <0 .0 5、P <0 .0 1)。 10 0次搬举后平均功率频率截距在L3左竖脊肌下降了 9% ,与搬举前比较 ,差异有显著性 (P <0 .0 5 ) ,其他部位下降不明显。结论　重复性的搬举可导致竖脊肌疲劳 ,L3部位比T10部位更容易疲劳 ;用中频截距的下降评价肌肉疲劳比用平均功率频率截距下降更敏感。     

基于AVR单片机的肌电信号生物反馈测试仪的设计

肌电信号(EMG)是一种伴随肌肉运动而产生的生物电信号,对表面EMG的分析研究可发现它与肌肉生理状态和肢体运动模式之间的对应关系。基于生物反馈技术研制肌电信号生物反馈仪采用AT-MEGA16 AVR单片机为核心元件,通过信号调理电路消除表面EMG工频干扰和噪声,并利用声光报警反馈肌肉紧张程度信息。本文介绍了肌电信号生物反馈仪的基本构成及其特点,并对肌电生物信号的特点和提取方法进行了分析,采用均方根值(RMS)法实时反映肌肉活动状态,试验结果表明本系统能有效缓解肌肉的紧张程度,在康复医学方面有较好的应用前景。     

Effect of mental and physical demands on muscular activity during the use of a computer mouse and a keyboard

OBJECTIVES: This study explores the effects of mental and physical demands on muscular activity in the use of the mouse and keyboard in computer work in a time-pressed situation. METHODS: Twelve female subjects performed a computer task with four combinations of two forms of input device (computer mouse and keyboard) and two levels of mental demand (with and without a color word test). The time available for response was limited. Performance and electromyography (EMG) were recorded for the forearm, shoulder, and neck muscles. RESULTS: The mean static muscular activity was 2-7% of the maximum EMG for the forearm and neck extensor muscles. All the muscles for which recordings were made showed increased muscular activity in the mentally demanding condition. The increase in the static muscular activity level varied from 0.3% of the maximum EMG for the right trapezius muscle to 2.6% for the extensor carpi ulnaris muscle. Significant differences in muscular activity between the use of a computer mouse and a keyboard were only found for the neck extensors; in the computer mouse condition there was a static EMG level of 3.5% for the maximum EMG, compared with 2.8% for the keyboard. CONCLUSIONS: Mental demands during computer work increased muscular activity in all of the recorded muscles. Increased muscular activity was found in the neck during the use of the mouse in comparison with the use of the keyboard; this phenomenon may be related to higher visual demands during the use of a mouse than with a keyboard. These findings may help explain the adverse effects of psychosocial work factors on the musculoskeletal system.     

Physiological limits in lifting

Two different experiments were conducted to study the effects of frequency, height and load of lift on computed maximal oxygen uptake and to compare the data obtained to a standard bicycle ergometer. A progressive submaximal technique was used to predict maximal oxygen uptake. The results of the present study revealed that across all heights, an increase in either the frequency of lift or load of lift was accompanied by an increase in computed maximal oxygen uptake; however, all maximal oxygen uptake values reported showed a tendency to level off beyond the frequency of five lifts/min. The results also showed that combined arm and leg lifting recorded the highest maximal oxygen uptake followed by leg lifting then arm lifting, respectively. Maximal oxygen uptake values obtained for lifting tasks were much lower than those obtained for a bicycle ergometer. It is therefore recommended that limits for continuous work for a lifting task be based on the attainable maximal oxygen uptake for that particular task and not on a maximal oxygen uptake obtained from another task such as a bicycle ergometer test.     

Pattern of muscle activity during stereotyped work and its relation to muscle pain

Summary Standardized and machine-paced work tasks at a packing machine were examined to evaluate interindividual variability of muscle activity patterns. Ten trained female workers, without musculo-skeletal complaints at the time of the recording, performed the work tasks while electromyographic (EMG) recordings were obtained from both upper trapezius muscles. Static muscle activity and periods of between 0.2 and 2 s duration with low muscle activity, EMG gaps, were analysed. Complaints of muscular fatigue, soreness or pain in the neck and shoulders during the last 12 months were recorded. The level of static muscle activity was 1.6 (range 0.4 to 2.5) per cent of maximal voluntary contraction and median number of EMG gaps was 4.8 (range 0.8 to 20) per minute. Workers with previous episodes of complaints (five subjects) had higher levels of static muscle activity and fewer EMG gaps than workers without such episodes (p < 0.05, Wilcoxon 2-sample test, one-tailed). Considerable interindividual variability of muscle activity patterns was found in spite of stereotyped work. No causal relations may be inferred from the correlation between the level of trapezius activity and complaints, though it indicates that individual, inexpedient muscle activity patterns may constitute an important risk factor for development of musculo-skeletal complaints.     

Effects of a new industrial lifting belt on back muscular activity, hand force, and body stability during symmetric lifting

This work investigated how wearing a new design of back belt affects erector spinae activity, hand force, and body stability. The belt was first tested with static holding tasks and found to significantly decrease the back muscle activity. Actual lifting tasks were further carried out to test the effect of the belt. Ten male subjects performed a symmetric lifting task of low-lying loads (11 and 16 kg) at natural toting velocity, using either a squat or stoop lifting posture, both with and without a belt. The study measured various independent variables using electromyography (EMG), load cells, and motion capture device. The results demonstrated that the belt reduced the load on the erector spinae, as well as the triceps brachii and biceps brachii. The overall mean values of the peak (hand) force did not appear significantly affected while wearing the belt, but the force peaks appeared postponed. The belt did not alter body stability while lifting. From the present findings, the belt effectively changed the force distribution during lifting, at least reducing the muscle load on the back. The belt may be a potentially useful device for symmetric industrial lifting tasks.     

生物反馈在压力性尿失禁非手术治疗中的价值

目的 通过Meta分析了解生物反馈在压力性尿失禁非手术治疗中的价值,旨在获得压力性尿失禁物理治疗的最佳方法. 方法 使用“biofeedback”及“stress urinary incontinence”及相应中文名关键词检索Pubmed、维普中文科技期刊全文数据库、万方数字化期刊全文、中国知网全文数据库所有文献,选取以生物反馈为对照治疗压力性尿失禁的文献,应用Review Manager 5.2软件进行统计学分析. 结果 共计18篇文献纳入研究.在压力性尿失禁非手术治疗中,生物反馈＋盆底肌锻炼与盆底肌锻炼对照治疗的有效率明显提高;生物反馈＋神经电刺激与盆底肌锻炼对照治疗的有效率明显提高;生物反馈＋盆底肌锻炼＋神经电刺激与盆底肌锻炼对照治疗的有效率明显提高,差异均有统计学意义. 结论 生物反馈在压力性尿失禁非手术治疗中有较好治疗效果,值得临床推广.     

神经康复重建疗法对痉挛型脑瘫肌张力的影响

目的观察神经康复重建疗法对痉挛型脑瘫患儿肌张力的影响。方法将24例痉挛型双瘫患儿随机分为治疗组和对照组,每组12例,所有患儿均接受Bobath技术、推拿、脑循环治疗。治疗组在以上基础上应用WOND2000172型神经康复重建仪,对双下肢进行肌电触发的生物反馈刺激。在疗程开始与结束时,用改良的Ashworth量表测定患儿腓肠肌肌张力的变化。结果治疗后,两组患儿的肌张力均有不同程度降低（P〈0．01—0．001）,但治疗组疗效优于对照组（P〈0．05）。结论神经康复重建治疗能有效降低痉挛型腑瘫患儿肌张力。     

Surface EMG of shoulder and back muscles and posture analysis in secretaries typing at visual display units

Objective: A study was carried out to investigate temporal changes of activation of shoulder and back muscles in workers at visual display units by means of surface EMG. Moreover, postural parameters were recorded to distinguish fatigue-related from posture-related changes of the myoelectrical activity. Methods: Nine healthy female office workers typed texts spoken from tape during three 1-h-long sessions. After the first and again after the second hour there was a break of 15 min. Sixteen-channel surface EMG was bipolarly recorded from the erector spinae, trapezius, deltoid and sternocleidomastoid muscles. Root mean square (RMS) and power spectrum median frequency of the EMG were calculated. Sitting posture was assessed using an eight-channel movement analysis system with ultrasound markers. The position of the seventh cervical spinous process and the left and the right acromion were analysed synchronously with the EMG characteristics using regression analysis. Results: The normalised RMS of the left and right trapezius muscle increased, while the median frequency did not change. The increase of the normalised RMS was significantly lower when the linear influence of posture was excluded. On average, the distance between C7 and the left and right acromion decreased within each working an hour. C7 became lower on average by 5.5 mm within an hour, whereas the acromions became lower by only 1.7 mm (left) and 3.3 mm (right). Conclusion: The increase in trapezius muscle activity was partly related to a lifting of the shoulders to compensate a slight slumping of the back. Another part of the EMG activity increase has to be attributed to fatigue, to attention-related activity or to the combination of both. Therefore, training of the back muscles and a varied organisation of work might have a preventive effect with respect to musculoskeletal complaints in VDU workers. Received: 18 September 1998 / Accepted: 9 May 1999     

Pattern of muscle activity during stereotyped work and its relation to muscle pain

Standardized and machine-paced work tasks at a packing machine were examined to evaluate interindividual variability of muscle activity patterns. Ten trained female workers, without musculo-skeletal complaints at the time of the recording, performed the work tasks while electromyographic (EMG) recordings were obtained from both upper trapezius muscles. Static muscle activity and periods of between 0.2 and 2 s duration with low muscle activity, EMG gaps, were analysed. Complaints of muscular fatigue, soreness or pain in the neck and shoulders during the last 12 months were recorded. The level of static muscle activity was 1.6 (range 0.4 to 2.5) per cent of maximal voluntary contraction and median number of EMG gaps was 4.8 (range 0.8 to 20) per minute. Workers with previous episodes of complaints (five subjects) had higher levels of static muscle activity and fewer EMG gaps than workers without such episodes (p less than 0.05, Wilcoxon 2-sample test, one-tailed). Considerable interindividual variability of muscle activity patterns was found in spite of stereotyped work. No causal relations may be inferred from the correlation between the level of trapezius activity and complaints, though it indicates that individual, inexpedient muscle activity patterns may constitute an important risk factor for development of musculo-skeletal complaints.     

不对称搬举劳动负荷及有关因素的表面肌电分析

目的 应用表面肌电描记术（SEMG）分析、评价不对称搬举的劳动负荷及有关因素.方法 13名男性志愿者以2种速度、4种躯干旋转角度,分别搬举重6和13kg的箱子,搬举箱子从地面至指节高度,共执行16项搬举任务.在搬举作业中测量T10和L3部位两侧竖脊肌的肌电信号.结果 搬举13kg重量时竖脊肌肌电平均幅度（43.30%MVE）明显比搬举6kg重量时（37.70%MVE）高,差异有统计学意义（P＜0.01）.快速搬举时的肌电平均幅度（41.80%MVE）明显比慢速搬举（39.19%MVE）时高,差异亦有统计学意义（P＜0.05）.随躯干旋转角度的增加,竖脊肌肌电幅度呈升高的趋势,但差异无统计学意义（P＞0.05）.在T10部位右侧竖脊肌肌电幅度高于左侧（分别为50.31%MVE、25.88%MVE）,而在L3部位则是左侧竖脊肌肌电幅度高于右侧（分别为45.60%MVE、40.22%MVE）,差异均有统计学意义（P＜0.01）.多元逐步回归分析结果显示,搬举重量对竖脊肌肌电平均幅度贡献最大,其次是搬举速度.结论 不对称搬举作业的工效学危险因素主要是搬举重量和速度.在不对称搬举时,左右两侧的竖脊肌肌电活性不同.     

3种盆底肌肉治疗方式对产后压力性尿失禁患者的治疗效果评估

目的:探讨3种不同的盆底肌肉治疗方式对压力性尿失禁产妇功能恢复临床疗效,寻找非手术治疗方法。方法:选择2014年9月-2016年1月在本院行产后42d检查患有压力性尿失禁的产妇,共118例,产妇随机分为3组,单独电刺激治疗30例(电刺激组);单独场景生物反馈训练治疗共31例(生物组);电刺激联合场景生物反馈训练治疗共46例(联合组)。所有对象治疗前测定的结果为初评,治疗5次为二评,治疗10次为三评。评估3组患者在应用3种不同方法治疗后盆底肌力、疲劳度、肌电位的变化。结果:所有对象二评结果、三评结果Ⅰ类肌力、Ⅱ类肌力均好于初评结果(P均0.05);Ⅰ类肌疲劳度、Ⅱ类肌疲劳度、肌电位差异没有统计学意义(P均0.05)。治疗后3组患者Ⅰ类肌力、Ⅱ类肌力、Ⅰ肌疲劳度、Ⅱ肌疲劳度均没有统计学意义(P均0.05)。联合组和生物组的肌电位均高于电刺激组(P0.05)。结论:3种治疗方式均能够改善患者产后的肌力,患者的自主评分均7分,漏尿程度较治疗前也有明显的改善。建议至少坚持5次盆底功能训练治疗疗效更好,联合组和生物组患者的肌电位最高疗效最好。     

Effects of mop handle height on shoulder muscle activity and perceived exertion during floor mopping using a figure eight method

The aim of this study was to investigate effects of mop handle height on electromyographic (EMG) activities of the shoulder muscles and perceived exertion for the shoulder area during floor mopping using a figure eight method. An experimental study with 13 cleaners was conducted using surface EMG and category ratio (CR-10) scale. EMG activity was recorded unilaterally from the upper trapezius, infraspinatus, anterior and middle deltoid muscles. Each subject performed four trials of mopping and each trial consisted of using a different mop handle height (mop adjustment at the level of shoulder, chin, nose and eye) in randomized order. EMG data were normalized to a percentage of maximal voluntary contraction (%MVC). The muscle activities were assessed by estimating the 10th, 50th and 90th percentiles of the amplitude probability distribution function (APDF) of the EMG signals and analysed by linear mixed model analysis. Results showed that shoulder muscle activity was significantly lower when the mop handle height was adjusted to shoulder level or chin level as compared to eye level. These findings were supported by subjective ratings of exertion. It seems that mop handle height adjustment between shoulder and chin level may be recommended as a basis for figure eight mopping.     

短时和快速傅里叶变换用于动态活动下表面肌电频谱分析的比较研究

目的短时傅里叶变换(short time Fourier transform,STFT)作为频谱分析的新方法比快速傅里叶变换(fast Fourier transform,FFT)更适合于非稳定信号,探讨这两种方法在分析评价动态活动肌肉疲劳的差异。方法9名男性大学生志愿者在实验室从事模拟的搬举活动(变换搬举重量和距离),测定搬举时左右两侧胸10和腰3水平竖脊肌的表面肌电信号。另10名志愿者在功率车上以3种速度跑步,记录此间双腿股内侧肌和股外侧肌的肌电。分别用STFT和FFT求得活动期间每秒钟肌电信号的中位频率(median frequency,MF),计算MF值依时间变化回归的斜率,比较两种算法所得结果的差异。结果搬举试验,STFT所得MF值多小于FFT,左侧胸10(LT10)、右侧腰3(RL3)竖脊肌比较,差异有统计学意义(P<0.05);右侧胸10(RT10)、左侧腰3(LL3)比较,差异无统计学意义(P>0.05)。STFT变异性多大于FFT。两种MF斜率比较,差异无统计学意义(P>0.05),然而二者间呈高相关性(r>0.5)。STFT与FFT疲劳检出率比较,差异无统计学意义(P>0.05)。跑步试验,两种方法计算所得4块肌肉MF比较,差异均无统计学意义(P>0.05)。STFT变异性多大于FFT。MF斜率和疲劳检出率比较,差异均无统计学意义(P>0.05)。两种MF斜率仍然呈高相关性(r>0.7)。结论至少在低负荷情况下,FFT依然可用于动态活动下肌电信号的频谱分析。仍值得进一步研究这两种频率变换方法以及EMG信号在不同活动和肌肉的特性。     

Distance training for the restoration of motor function

We reviewed the literature on distance training for the restoration of motor function. Computerized literature searches were performed using the MEDLINE, EMBASE, Cinahl and Cochrane databases. Articles that met the criteria for inclusion were divided into three general areas concerning the type of training in relation to motor functions--muscle/joint, balance and cognition. From the publications identified in the literature search, 11 articles met the selection criteria. Six were related to muscle/joint functions, four to balance functions and one to cognitive functions. The articles were graded according to the strength of the scientific evidence they offered. The review revealed some promising applications of distance motor training, such as virtual reality (VR) and robotic devices. The strength of the evidence from these studies was poor, however, probably because the technology is relatively new. In contrast to the studies using VR and robotic devices, those using electromyographic (EMG) biofeedback showed a good to fair strength of scientific evidence. This can be explained by the substantial history of research on the restoration of motor function through the use of EMG biofeedback techniques. When implemented in clinical practice, these applications could reduce the pressure on scarce health-care resources.     

Trapezius muscle load as a risk indicator for occupational shoulder-neck complaints

Summary Upper trapezius muscle activity was quantified by electromyogräphic (EMG) recordings using surface electrodes to study occupational muscle load as a risk indicator for the development of shoulder-neck complaints. Thirty-nine female' production workers and thirty-two female office workers showed much larger interindividual differences than the mean difference in muscle activity between the two groups. By comparison with the production workers, the muscle activity patterns of the office workers were characterized by more short pauses and a lower static load. The median load level was similar for the two groups. For the office workers, but not for the production workers, weak correlations were found between symptoms of pain in the shoulder-neck region and some of the EMG parameters (static level and frequency of micropauses > 0.6 s. Current techniques for measuring shoulder muscle load by EMG recordings seem inadequate as screening methods to predict future risk of development of muscle pain symptoms.     

The effect of obesity on postural stability during a standardized lifting task

The objective of this study was to assess the effect of obesity on postural stability during a standardized lifting task. Twelve young males, six obese and six non-obese, completed three replications of repeated six lifts (at a rate of six lifts per minutes) at two levels of loads (10% and 25% of capacity) crossed with two levels of orientation (0° and 45° from sagittal plane). Postural stability measures showed that center of pressure sway path and sway area were ～21% and ～53% lower with obesity, respectively. Additionally, frequency band of amplitude spectrum in the medial lateral direction at 0° lifting orientation was significantly lower with obesity. The results suggest that obesity, as measured by body mass index, does not impair balance control in healthy young males when lifting load is relative to the capacity.     

EMG Biofeedback Training to Promote Hand Function in a Cerebral Palsied Child with Hemiplegia

This paper will describe how EMG biofeedback can be used in training a hemiplegic cerebral palsied child. Specifically will be described how EMG biofeedback will promote relaxation of spastic upper-extremity muscles and active movements of antagonistic muscles, for potential improvement in hand function. To illustrate the biofeedback approach used, a case study will be presented.     

Gait muscle activity during walking on an inclined icy surface

The objective of this study was to explain the contribution of lower extremity muscle activity to gait kinetic and kinematic adaptations for maintaining gait dynamic balance when walking on an inclined icy surface and the biomechanical mechanisms used to counteract slip risk. A two-way factorial experimental design was applied. The two independent variables were the walkway surface (ice and treadmill) and the walkway inclination (0 masculine, 6 masculine, 8 masculine). The dependent variable was the amplitude of the surface EMG of four right lower extremity muscles (tibialis anterior TA, gastrocnemius lateralis GL, rectus femoris RF, and biceps femoris BF). Twelve healthy subjects (7 males and 5 females) participated in the walking trials. A two-way ANOVA analysis showed that on the icy surface in the heel contact phase, EMG amplitudes significantly decreased in TA and RF compared to those for the treadmill surface. In the mid-stance phase, the GL muscle activity significantly decreased on ice compared to treadmill and all four muscle activities increased significantly with the inclination. During the toe off phase, GL and RF activities increased with the inclination. The mechanisms identified may be applied to develop intervention, rehabilitation and training techniques, and to improve performance in human locomotion, such as for winter sports.     

Prevalence of musculoskeletal disorders among Indian railway sahayaks

Railway sahayak or also known as coolie is one of the oldest occupations in India. This occupational group is continuously subjected to various musculoskeletal problems due to repetitive load exertion in unnatural postures. The present research aims to examine the prevalence of musculoskeletal disorders (MSDs) among Indian railway sahayaks. A cross-sectional study has been conducted on a sample of 51 male sahayaks. With a modified Nordic questionnaire, data were collected on their demographics, work, and musculoskeletal pain history. Electromyography (EMG) of the upper trapezius muscle of selected 12 healthy sahayaks having no history of neck–shoulder complaints were analyzed under different load lifting and carrying conditions. Additionally, ergonomic risk levels were recorded using Rapid Entire Body Assessment method. The questionnaire revealed that for the past 1 year prevalence, the most affected body regions of railway sahayaks were neck (47%), shoulder (51%), lower back (43%), and knee (47%). The association between age group and MSDs in different body regions were found significant (p = 0.012 for neck, p = 0.017 for shoulder, etc.). Work experience also had a significant relation to the MSDs in different body regions (p = 0.013 for shoulder,p = 0.023 for calf, etc.). Analysis of variance reveals high significance level between EMG values and tasks performed by the sahayaks. In conclusion, railway sahayaks were found to have high rate of MSDs which may be associated with lifting/carrying heavy loads in awkward postures. Ergonomic interventions must be implemented to reduce the risk level on this group of workers.