男性受试者搬举MAWL和RWL时的劳动负荷评价

目的对手工搬举方程在我国应用的适合性进行研究,为我国制订手工搬举作业劳动负荷的标准提供依据。方法用表面肌电信号技术和Borg量表对男性受试者搬举最大可接受搬举重量(MAWL)和推荐搬举重量(RWL)时的劳动负荷进行了评价。结果受试者对称搬举MAWL时竖脊肌肌电幅度在50%~70%MVE(最大自主收缩时肌电幅度)范围内波动,对称搬举RWL时在41%~71%MVE范围内波动。在水平距离25 cm处,从地面到可触及高度,搬举RWL时竖脊肌肌电幅度比搬举MAWL时高7.51%。从指节到可触及高度,搬举RWL时竖脊肌肌电幅度比搬举MAWL时高13.08%。非对称搬举MAWL时的竖脊肌肌电幅度明显高于搬举RWL时,差异有统计学意义(P<0.01)。身体各部位搬举MAWL时的自我用力感受(RPE)评分都明显高于搬举RWL时的RPE。结论美国职业安全卫生研究所(NIOSH)搬举方程对于水平距离和不对称的校正是充分的,但对于高度的校正是不足的,尤其是对于过肩的搬举作业是不适合的,对于过肩搬举作业的推荐搬举重量限值还应降低。     

女性搬举最大可接受重量时的劳动负荷评价

[目的]研究女性手工搬举的最大可接受重量,为手工搬举作业劳动负荷标准的制定提供参考依据。[方法]用表面肌电信号技术(SEMG)和Borg量表对女性受试者搬举最大可接受重量时的劳动负荷进行评价。[结果]受试者对称搬举最大可接受重量时竖脊肌肌电幅度波动在59%～87%最大自主收缩时肌电幅度(%MVE)范围内。女性的最大可接受搬举重量远远低于根据NIOSH1991方程计算出的推荐搬举重量限值。在相同的高度,随着水平距离的增加,竖脊肌肌电幅度、RPE(Rating of Perceived Exertion)评分逐渐增加。不对称搬举最大可接受重量时不同扭转角度之间的竖脊肌肌电幅度差异无显著性,P>0.05。身体各个部位的RPE评分与扭转角度呈正相关,相关系数r>0.98,P<0.01。[结论]本次实验所搬举的重量确实为受试者的最大可接受搬举重量,NIOSH搬举方程应用于女性时应适当降低推荐搬举重量限值。     

木工推台锯岗位手工搬举作业腰部受力生物力学分析

目的 评估木工推台锯岗位手工搬举作业中是否存在导致职业性下背痛和职业性肌肉骨骼疾患(WMSD)发生的职业性风险,并进一步提出预防与降低WMSD风险的合理工作方式和干预措施.方法 应用美国职业安全卫生研究院(NIOSH)抬举方程,分析木工推台锯岗位中常见的抬举作业任务,并建立该搬运作业的腰椎生物力学模型,计算该作业典型姿势下腰椎间盘(L5/S1)的负荷.结果 随着抬举作业起始面高度的变化,提举重量推荐值(RWL)随之变化,并且呈现出类抛物线的变化规律,最低值为9.05 kg;在搬运作业中,作用在L5/S1上的外力合力为3579 N;其中,挤压力为3570 N,略大于NIOSH提出的年轻健康工人耐受限值3400 N.家具制造木工推台锯岗位MMH作业人员腰椎受伤的可能性较大.结论 木工推台锯岗位手工搬举作业时,存在导致职业性下背痛和WMSD发生的职业性风险;为避免职业性损伤的发生,该岗位的手工搬举作业的任务宜进行优化设计.     

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.     

表面肌电和心电评价手工搬举技术的实验研究

目的探讨表面肌电和心电技术评价不同手工搬举下腰背部竖脊肌的劳动负荷,以期获得最佳搬举技术。方法30名大学生志愿者在实验室模拟手工搬举作业,分别测定和分析蹲举、背举和半蹲举的左、右侧胸10水平竖脊肌(LT10、RT10)和腰3水平竖脊肌(LL3、RL3)表面肌电、心率和Borg量表分值的变化情况。结果3种搬举技术下,男性LT10、RT10和女性LL3、RL3竖脊肌表面肌电幅度均方根值的最大随意收缩百分比(percentage of maximum voluntary electrical activation,MVE%)均较休息时高(P<0.05)。男性LT10、LL3和女性RT10、LT10的MVE%在蹲举时最高(P<0.05)。女性RL3的MVE%在半蹲举时最低(P<0.05),而女性LL3的MVE%在背举时最低(P<0.05)。男性LT10和女性LT10、LL3的中位频率(MF)均高于休息时的值(P<0.05),而男性、女性RL3的MF值均低于休息时的值(P<0.05)。3种搬举技术下,男性、女性的MF值无统计学意义。与休息时比较,3种搬举技术下,男性、女性心率均高于休息时的值(P<0.05)。男性、女性...     

手工搬举的限值与复合搬举任务评价进展

与手工搬举 (manualmaterialshandling ,MMH)工作有关的肌肉骨骼疾患 (musculoskeletaldisorders,MSDs)是目前发达国家主要的工作有关疾患 ,也是职业赔偿的主要疾患之一 ,而过度用力则是MMH损伤的常见原因[1,2 ] 。随着经济一体化的发展 ,MSDs也越来越受到国人的重视。为预防MSDs的发生 ,许多学者从牛顿力学、心理物理学以及生理学机制来定量评价MMH任务 ,从而达到识别、评价和控制手工搬运危险因素的目的 ,并据此提出有关的限值[3 ] 。现就有关研究进展综述如下。一、手工搬举限值的发展不同专业的学者对MMH任务如举 (lifting)、…     

民航手工搬举作业人员下背痛现状与预防

<正>随着现代工业技术的迅速发展,很多行业生产工艺已基本实现机械化、自动化。而在许多服务领域和制造业中手工提举却仍然普遍存在,与手工搬运提举有关的肌肉骨骼疾患(MSDs),特别是下背痛(LBP)发病逐渐增多[1,2],已引起企业及国内职业卫生领域的关注。民航手工搬举作业包括沉重货物或行李的提举、移动、分拣、运载和装卸等操作,广泛存在重负荷、推拉、搬举、频繁重复性弯腰、屈膝、扭转等不良姿势和负荷作业中,是导致作业人员工作相关肌肉骨骼疾患(WMSDs)的重要因     

手工搬运作业人体工效学评价方法实例应用

目的探讨建立手工搬运作业工效学评价方法,并在建设项目职业病危害评价工作中应用。方法选择某半导体企业锂电池生产车间87名存在手工提举作业的工人为接触组,采用调查问卷、统计分析、NIOSH提举指数等评价方法,对手工提举作业的不良工效学负荷进行人体工效学评价。结果该企业为电子加工行业,存在明显的不良工作姿势和手工提举任务的特点;经统计学处理分析,该公司车间作业工人肌肉骨骼损伤的发生率与对照组的差别尚无统计学意义(P0.05),分析不相关的原因主要为本次评价作业工人年龄偏小、工龄短等因素影响;根据我国人体数据修正过的NIOSH提举指数对搬举作业人体工效学进行定量评价,说明现有作业环境存在诱发作业者搬举疲劳的风险因素,但未达到肌肉骨骼疾患发生风险明显增加的程度。结论长期手工提举等作业可能导致与此有关的肌肉骨骼疾患,但我国尚未将职业性腰背痛列入职业病名单,也未制定手工提举指南和重量限值,今后应在建设项目职业病危害评价工作中开展手工提升或搬运作业工效学评价,加强生产环节的职业病危害防护,防止发生职业危害。     

工人和学生最大静态肌力的测定与分析

目的测量工人和学生两组人群的最大肌力,为制定适合我国人群的手工搬举标准提供依据。方法按照《人体测量学指导手册》测定938名受试者的基本人体尺寸,通过拉力测试系统测定受试者的背提力、左右手提力、手臂提力和肩提力。结果测得男性背提力、左右手提力、手臂提力、肩提力的最大值男性分别为1 077.0、576.9、609.0、318.3、465.1N,女性分别为602.0、306.6、340.9、181.8、252.3N。背提力最大,手臂提力最小。男性受试者人体尺寸和最大肌力呈现一定的相关性(P0.05)。结论中国人背提力、单手提力、手臂提力和肩提力均低于欧美人群。女性各种肌力均比男性小,总体上是男性肌力的55%左右。在女性当中左手肌力小于右手肌力更加明显。     

最大可接受提举重量的研究

目的 探讨中国青年男性的最大可接受提举重量,验证美国职业安全卫生研究所(NIOSH)提出的提举重量限值能否在中国应用.方法 11名年轻男性大学生参加试验.通过心理物理学方法,获得不同提举频率下的最大可接受提举重量、心率和用力自我感受,提举高度为从地面到工作台(760mm).结果 与NIOSH建议值和美国利宝集团研究结果进行比较.结果 年轻男性的一次最大可接受提举重量为34.1kg,而1、4、8次/min的最大可接受提举重量则分别为17.4、14.7、12.2 kg.结果 明显低于NIOSH的推荐限值.结论 应用NIOSH提举公式时应作调整,如降低提举重量常数和提举频率系数等.     

Psychophysically determined asymmetrical lifting capabilities for different frequencies and containers

Ten young male participants were tested their psychophysically determined 4-h maximum acceptable weight of lifting (MAWL) of 90-degree asymmetric lifting for three lifting frequencies (1 lift/min, 2 lifts/min, 4 lifts/min) and three lifting containers (50 x 35 x 15 cm, 70 x 35 x 15 cm, 50 x 50 x 15 cm). The results showed that the MAWL decreased with increasing frequency and container width or length dimension, while the interaction effect of frequency and container on MAWL was not significant. The MAWL ranged from 13.7 kg to 18 kg for the nine (3 frequencies x 3 containers) lifting conditions. When averaged across the levels of the other independent variable, the MAWL decreased by 7.4% and 16.1% for 2 lifts/min and 4 lifts/min as compared with the MAWL of 1 lift/min, respectively, and decreased by 1.6% and 9.4% for 70 x 35 x 15 cm and 50 x 50 x 15 cm as compared with the MAWL of 50 x 35 x 15 cm, respectively. Additionally, the discrepancies between the MAWL data and the recommended weight limits derived from the revised NIOSH equation were discussed.     

An evaluation of the NIOSH guidelines for manual lifting, with special reference to horizontal distance

A laboratory study was conducted to determine the percentage of subjects capable of lifting loads at the maximum permissible limit (MPL) and the corresponding energy expenditure, heart rate, compressive force on the L5/S1 disc, and ratings of perceived exertion. A second objective was to compare MPLs based on measured horizontal distances with those based on the rule of thumb proposed in the National Institute for Occupational Safety and Health (NIOSH) guide (H = 15 + w/2 cm). Thirteen male subjects were required to lift three different boxes (25, 38, and 51 cm wide) at four different frequencies (0.2, 3, 6, and 9 lifts/min) and at two heights (floor level to bench height [0.8 m] and bench height to 1.5 m). Each lift was performed for 1 hr, and horizontal distances for all 13 subjects were measured at the origin of the lifts. MPLs were computed for all lifting tasks. A psychophysical method was used to determine the maximum acceptable weight of a lift. This weight, however, was not allowed to exceed the corresponding MPL. Maximum acceptable weights for all 13 subjects were equal to the MPLs. Of 13 subjects, 9 indicated that they could lift weights significantly greater than the MPLs. MPLs for the bench to 1.5-m height were significantly greater than the corresponding MPLs for the floor to 0.8-m height. The mean heart rate for 1-hr lifting tasks ranged from 104 to 114 beats/min. The estimated compressive force on the L5/S1 disc ranged from 340 to 598 kg. The mean ratings of perceived exertion for floor level to bench height and bench height to 1.5-m lifts were 12 and 9.6 for the back and 9.3 and 13 for the shoulder, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Can Chinese MAWL be used for designing manual handling tasks?

Previous studies have employed collected MAWL (maximal acceptable weight of lift) data as criteria for designing manual handling tasks because MAWL relates to one's limitation of muscle strength. However, whether the Chinese MAWL can still be used for job design is questionable because the Chinese are relatively weaker than Western subjects in their upper extremities. To clarify this, in the present study 24 male Chinese subjects psychophysically determined their MAWL and MAWLo (maximal acceptable weight of lower) under task conditions of three lifting frequencies and two lifting ranges. The results indicated that subjects' MAWLo were significantly lower than their MAWL, especially when infrequent tasks were performed (including tasks of one time maximum and one lift (lower)/min, all p<.05). This could be attributed to a relatively disadvantageous position in the upper extremities at the beginning stage of these lowering tasks. This finding strongly implies that it is not enough to consider only Chinese MAWL when designing manual handling tasks; MAWLo data should not be ignored.     

Maximum weights of asymmetrical loads acceptable to industrial workers for symmetrical manual lifting

This paper presents 'maximum acceptable weight of lift' design databases for lifting asymmetrical loads by industrial male and female workers. These databases were developed by first collecting experimental data on experienced and inexperienced workers under identical conditions (Study A) and then applying the trends developed, as a result of data comparison, to the data collected on inexperienced workers in a separate independent study (Study B) dealing with lifting asymmetrical loads. Several different task variables are accounted for in the data. These include the following: lifting height (floor to knuckle, knuckle to shoulder, and shoulder to reach); frequency of lift (2, 4, and 6 lifts/min; box-size (30.48, 45.72, and 60.96 cm long in the sagittal plane); and load asymmetry (indicated by the offset of the center of gravity in the frontal plane: 0, 12.7, and 25.4 cm from the mid-sagittal plane; the 0 cm center of gravity (c.g.) offset indicates symmetrical load).     

Maximum Weights of Handling Acceptable to People Aged 55–74 Years: Part I. Lifting

The primary objective of this work was to investigate dynamic psychophysical (acceptable) material handling strengths (capabilities) of an older population (aged 55–74 years; n = 20). The findings are presented in two parts. Part I deals with manual lifting capabilities; Part II deals with manual carrying capabilities. In order to determine dynamic psychophysical strengths, routine everyday tasks were simulated in the laboratory. Lifting activities simulating work-related tasks included eight sequences of lifting (two lifting heights × four lifting frequencies); for each sequence, the maximum acceptable weight of lift (MAWL) was determined. Psychophysical lifting strengths of a younger population (18–35 years; n = 20) were also determined to find how the MAWL of the older population differed from that of the younger population. In addition to the MAWL, a number of responses at the MAWL were recorded: heart rate (HR), oxygen uptake (VO₂), and category-ratio ratings of perceived exertion (CRRPE). The results indicated no practically significant age-related differences in responses between either the older and younger males, or older and younger females. Based on the limited data collected in this study, it appears that age has no significant influence on people's capability to lift loads. Consequences of these findings on design are discussed.     

Lifting strengths in different horizontal distances of objects to be lifted

This study recruited eleven healthy males and thirteen healthy females to examine their maximum two-handed isometric back lifting strength, upper-body lifting strength, arm lifting strength and shoulder lifting strength in three different horizontal distances of objects to be lifted (toes were anterior to, aligned with, and posterior to the exerted handle). The results showed that human lifting strength decreased significantly as the toe position shifted from anterior of the vertical plane of the exerted handle to posterior of the vertical plane of the exerted handle. The strength order relationship between back lifting strength and upper-body lifting strength was dependent on the horizontal distance of objects to be lifted. This study also observed that the effects of the horizontal distance of objects to be lifted on human lifting postural angles for the four assessed lifting types mainly occurred in the upper extremities. This study recommends that practitioners should not overlook the effects of the horizontal distance of objects to be lifted on lifting strength when evaluating workers' lifting strength for screening purposes.