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91.
Despite substantial epidemiological evidence relating overhead exertions with work‐related musculoskeletal disorders (WMSD) of the neck, effects of such exertions on the loading of neck or cervical spine musculature are not well understood. In this study, the effects of overhead pushing and pulling exertions on the loading of the cervical spine were evaluated using electromyography (EMG) and subjective discomfort ratings. Additionally, the role of gender as well as individual strength on the loading of neck musculature during such exertions was evaluated. Twenty‐four healthy individuals (12 men and 12 women) participated in this study. Each participant performed overhead pushing and pulling exertions, exerting 25%, 50%, and 75% of their respective maximum strengths. Overhead pushing exertions were found to be significantly more strenuous to the neck musculature than were the pulling exertions. Gender had no significant effect on the activities of the neck muscles. Participants with high strength, however, were able to exert more force at comparatively low muscle activation levels. Subjective discomfort ratings were strongly correlated with the EMG data. At various workplaces, avoiding overhead exertions is rather impossible due to material, interface, and site constraints. Based on the results of this study, however, during such exertions, an interchange between directions of force application could prevent sustained loading of the neck muscles, fatigue, and consequently the probability of neck WMSD incidents. © 2011 Wiley Periodicals, Inc.  相似文献   
92.
《Ergonomics》2012,55(7):1125-1133
We examined the differences in muscle tension and in physiological measures depending on the type of mental task. Fifteen participants performed tests for sustained attention, vigilance and maintaining posture only. We analysed electromyogram (EMG) measures of extensor digitorum (ED), flexor carpi ulnaris (FU), deltoideus (DE) and trapezius (TR), and heart rate (HR) and respiratory frequency (RF). Measures indicated higher values for mental tasks than for maintained posture only with significant differences in all measures. The following relationships were also significant: between DE and physiological measures (HR and RF), between ED and the amplitude of EMG of the other three muscles, between FU and TR and between HR and RF. The results of this study showed that the relationship between mental demands and muscle tension was mostly reflected by tension in the arm and shoulder girdle muscles and, to a lesser degree, in forearm muscles.

Practitioner Summary: We focused on physiological and muscle tension measures differentiating work according to the level of mental demands. Differences in sustained attention, vigilance and maintaining posture only proved that mental demands were mostly reflected by tension in arm and shoulder girdle muscles and, to a lesser degree, in forearm muscles.  相似文献   
93.
In recent years, consumers' emotional responses have been found to be an important complement to sensory and hedonic evaluations for the prediction of food choice and consumption behaviour. Given this trend, it is essential that the influence of contextual variables on emotion are investigated. The present study contributes to the discussion with an investigation of the effect of social context on implicit emotional responses to food images. 87 participants (56 female, 31 male) viewed food images of varying acceptability either alone, with a stranger, or with a friend. Subjective liking ratings were measured using a labelled affective magnitude scale, and facial muscle activity from zygomaticus major (contracted during smiling), corrugator supercilii (contracted during frowning) and levator labii superioris (contracted during nose wrinkling) were measured with an EMG recording system. Controlling for individual differences in facial expressivity and food image acceptability using linear mixed models, it was found that the presence of a co-acting stranger facilitated muscle activity indicative of a disgust response, increased the strength of relationship between muscle activity and subjective liking ratings, and led to lower subjective liking overall. No differences in muscle activity or subjective liking were found between subjects who participated alone and with a co-acting friend. This suggests that the influence of social context is complex, where the relationship between the subject and the social environment can impact both hedonic and emotional evaluations of food stimuli. These findings indicate that facial EMG can be a useful dynamic and implicit measure of emotion in consumer research, but it is critical to consider the social context of the testing environment.  相似文献   
94.
在开发传统的sEMG识别控制系统时,一般采用软件算法研究与硬件实现相分离的方法,容易造成识别控制算法的“理想化”.设计一种基于虚拟仪器的sEMG识别控制系统,该系统平台基于LabVIEW及数据采集设备、MATLABScrip节点程序和机械臂执行机构,实现了对sEMG识别控制系统的半实物仿真控制,使算法研究与硬件实现相结合,缩短了真实系统的开发时间,提高了控制算法的准确性和实用性.  相似文献   
95.
EFFECTS OF SAMPLE THICKNESS ON BITE FORCE FOR RAW CARROTS AND FISH GELS   总被引:2,自引:0,他引:2  
The effects of food thickness on human bite force were investigated using a multiple‐point sheet sensor and electromyography. The total force and contact area were directly measured in real time using the sensor, and the average stress detected between the teeth and a food sample (active stress) was derived from the ratio of the force to the contact area. Raw carrots and fish gels with different thicknesses were bitten between the upper and lower incisors or molars by healthy women. For hard and brittle carrots, the peak force, contact area and active stress at the fracture point were greater in thicker samples when biting with incisors. For soft and tough gels, the peak force and contact area were increased as thickness increased; however, the active stress was similar in incisor bites. These values did not differ significantly with thickness in the molar bites of both samples. Although the force and contact area were greater for molar bites than incisor ones, the active stresses at fracture point were independent of tooth position. The sample thicknesses influenced the bite force of humans and the stress applied to the sample, and the effects differed with sample texture.  相似文献   
96.
The existing research of steering efficiency mainly focuses on the mechanism efficiency of steering system, aiming at designing and optimizing the mechanism of steering system. In the development of assist steering system especially the evaluation of its comfort, the steering efficiency of driver physiological output usually are not considered, because this physiological output is difficult to measure or to estimate, and the objective evaluation of steering comfort therefore cannot be conducted with movement efficiency perspective. In order to take a further step to the objective evaluation of steering comfort, an estimating method for the steering efficiency of the driver was developed based on the research of the relationship between the steering force and muscle activity. First, the steering forces in the steering wheel plane and the electromyography (EMG) signals of the primary muscles were measured. These primary muscles are the muscles in shoulder and upper ann which mainly produced the steering torque, and their functions in steering maneuver were identified previously. Next, based on the multiple regressions of the steering force and EMG signals, both the effective steering force and the total force capacity of driver in steering maneuver were calculated. Finally, the steering efficiency of driver was estimated by means of the estimated effective force and the total force capacity, which represented the information of driver physiological output of the primary muscles. This research develops a novel estimating method for driver steering efficiency of driver physiological output, including the estimation of both steering force and the force capacity of primary muscles with EMG signals, and will benefit to evaluate the steering comfort with an objective perspective.  相似文献   
97.
一种新型的表面肌电检测与训练系统的软硬件设计   总被引:1,自引:1,他引:0  
表面肌电检测与训练系统是开发出来用于保健、训练、检测,提高人民生活水平的产品。它具有实用性、便携性,易于操作。表面肌电检测与训练系统由两个主要平台构成:PC计算显示存储平台和下位机采集、显示、传输、存储平台。下位机硬件为ARM7数字处理中心和前端放大滤波模拟处理电路;下位机软件为带触摸屏的嵌入式系统,有USB传输、WiFi无线传输,SD储存等模块,方便高效。上位机实现对肌电信号的非线性动学分析和反馈治疗训练。这个系统具有可行性和灵活性,可用于更深层次的研究。  相似文献   
98.
肌电信号的功率谱分析方法   总被引:8,自引:0,他引:8  
当用传统的检测方法对肌电信号(EMG)进行处理时,会出现较大的个体差异,针对这一不足,我们对其在频域中作具体的分析,提出了一种新的表面肌电信号特征提取方法--功率谱比值法.并在非特定人的条件下,经过多次实验确定实际所用肌电信号的主要频率范围和功率谱的各项参数,将功率谱比值法应用于前臂肌群的表面EMG特征提取,减小了个体差异,进而实现非特定人的动作模式识别.  相似文献   
99.
为了满足手部运动功能康复器的主动康复训练对多种人手动作模式识别的需求,分析了表面肌电信号采样通道设置布局、训练样本制作、特征提取方式、模式分类器结构参数等因素对手部动作识别的影响,设计了针对前臂的表面肌电信号采集方案,分别基于时域统计量、自回归模型系数、小波包分解系数特征设计了BP神经网络分类器。实验结果表明:对6种单指动作、13种多指动作、20种手部动作的最佳平均识别率分别为98.5%、92.4%、90.9%,计算时间小于190 ms,验证了所提出方法的有效性和实用性。  相似文献   
100.
Phosphorus (P) deficiency and hypophosphatemia are believed to be associated with muscle function disturbances in dairy cows, particularly around parturition. The objective of this study was to determine the effect of dietary P deprivation during late gestation and early lactation on muscle P homeostasis and muscle function in periparturient dairy cows. Thirty-six multiparous dairy cows in late gestation were randomly assigned either to undergo dietary P depletion or to be offered a diet with adequate P content from 4 wk before to 4 wk after parturition. Phosphorus-deficient rations for dry and lactating cows contained 0.15 and 0.20% P on a dry matter basis, respectively. Blood and muscle tissue for biopsy were obtained and electromyographic examinations were conducted on biceps femoris and intercostal muscles in regular intervals throughout the study. Muscle tissue was analyzed for the total P, adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, creatine phosphate, and tissue water content. Dietary P deprivation resulted in a pronounced and sustained decline of the plasma phosphate concentration, reaching a nadir at calving with mean values below 1.5 mg/dL and remaining below 2.0 mg/dL during the first 4 wk of lactation. Hypophosphatemia was not associated with signs of clinically apparent muscle weakness or disturbed muscle function and was not associated with a decline in the content of any of the studied P-containing compounds in muscle tissue. Accordingly, no association between plasma phosphate concentration and muscle tissue P content was found. Electromyographic examination identified subclinical effects on motor unit action potentials that are indicative of disturbed neuromuscular functionality. Increasing occurrence of pathologic spontaneous activity possibly resulting from membrane instability of nerve or muscle cells and suggestive of myopathy was also recorded as P deprivation progressed. These effects were predominantly observed in intercostal and to a lesser degree biceps femoris muscles. Electromyographic parameters affected by P deprivation were found to be associated primarily with the plasma phosphate and to a lesser extent with the amounts of energy storing P-containing compounds contained in muscle tissue. These results indicate that prolonged and pronounced dietary P deprivation in transition dairy cows leads to marked sustained hypophosphatemia without altering the muscle tissue P homeostasis or causing clinically apparent muscle function disturbances.  相似文献   
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