Occupational Ergonomics - Volume 1, issue 4

Authors: Keller, Erwin | Strasser, Helmut

Article Type: Research Article

Abstract: This study assessed the effects of a wrist rest for VDT operators based on an experimental investigation. Muscular strain associated with the working posture was measured continuously via electromyographic activities (EA) of 8 muscle groups which were involved in the working tasks. The electromyographic measurements yielded a clear systematical effect of the wrist rest while entering text using the 10-finger touch system. Values of the EA, as an indicator of physiological cost were essentially lower with the wrist rest. Working without the wrist rest is at least two times more strenuous than working with it. The differences are statistically highly …significant. Less positive and less consistent results were found while working on the prefixed mouse pad of the wrist rest. Considering the influence of the working aid on entering text, the results of the subjective assessment after the tests corresponded well with the objectively measured physiological data. Whereas the working aid for entering text was assessed quite positively overall, the integrated mouse pad earned a clearly negative rating. Show more

Keywords: Multi-channel electromyography, wrist rest, subjective ratings, ergonomic quality

DOI: 10.3233/OER-1998-1401

Citation: Occupational Ergonomics, vol. 1, no. 4, pp. 239-257, 1998

Authors: Nevala-Puranen, Nina | Halonen, Merja | Tikkanen, Ritva | Arokoski, Jari P.A.

Article Type: Research Article

Abstract: Changes in the work techniques, physical capacity, musculoskeletal symptoms and work ability of hairdressers were studied after occupationally oriented medical rehabilitation for pain symptoms in the neck and shoulders, upper limbs or back. The measurements were carried out in the beginning of the rehabilitation course and after a follow-up period of 1.5 years. The synchronized video-electromyographic data on each subject's habitual work techniques were utilized in teaching and training for improving the ergonomic characteristics of the hairdressers' work. The mean muscle activity of the trapezius muscles was 612% voluntary contraction (MVC) in the beginning of the rehabilitation and 38% follow-up. …The musculoskeletal pain index decreased from 5.0 to 2.6 (p=0.03) during the follow-up. This result showed that the occupationally oriented rehabilitation had positive effects on the hairdressers' daily work techniques, physical capacity, work ability, and subjective well-being. Show more

Keywords: Hairdresser, rehabilitation, ergonomics, work technique, electromyography

DOI: 10.3233/OER-1998-1402

Citation: Occupational Ergonomics, vol. 1, no. 4, pp. 259-268, 1998

Authors: Quintana, Rolando | Barrón García, Etelvina

Article Type: Research Article

Abstract: A work design and evaluation methodology was developed for the design of new workstations, or to evaluate and improve existing ones in industry. This audit methodology will address ergonomic, productivity, and International Standards Organization compliance requirements. The methodology was implemented and tested in an automobile wire harness inspection workstion. Upon analysis and experimentation, the work design and evaluation methodology was shown to have face and construct validity. The re-design of the evaluated workstation based on the methodology resulted in the minimization of ergonomic disorder hazards, and a 44% increase in throughput.

Keywords: Work design, work evaluation, job analysis, ergonomic compliance

DOI: 10.3233/OER-1998-1403

Citation: Occupational Ergonomics, vol. 1, no. 4, pp. 269-283, 1998

Authors: Abib, Abdillahi H. | Dutta, Sourin P.

Article Type: Research Article

Abstract: Several physiological factors, such as wrist, back, and neck injuries, and vision strain contributing to lost workdays in different types of industries using video display terminals (VDTs) were examined using multi-regression model. The developed linear multi-regression model showed that the presence or absence of neck injuries data gives the same result, although the data of neck injuries were highly correlated with dependent variable, workdays lost in comparison with other independent variables. The most important result from this model showed that the combination of back injuries and vision strain data have high correlation coefficient value. The position of worker's back affects …his/her vision strain. Findings of this study show that wrist, and back injuries, and vision strain are the main contributors to the workdays lost. Since the numbers of workers using VDT are going up due to advanced technologies, the number of injuries related with VDT will go up dramatically if necessary actions are not taken. Show more

Keywords: Wrist, back and neck injuries, vision strain, workdays lost, video display terminals, regression model

DOI: 10.3233/OER-1998-1404

Citation: Occupational Ergonomics, vol. 1, no. 4, pp. 285-290, 1998

Authors: Yang, Yung-Nien | Karwowski, Waldemar | Lee, Yung-Hui

Article Type: Research Article

Abstract: This paper examines interrelationships between the cognitive concepts of load heaviness, perceived weight lifted, and the size-weight illusion effect, and their importance for setting load limits in manual lifting tasks. Results of three related studies are presented, including: (1) a questionnaire survey of the perceived relationship between physical weights and subjective perception of load heaviness for a large subject population; (2) modeling of the above relationship using the fuzzy linguistic approach; and (3) laboratory examination of the perceived weights and load heaviness for five pre-weighted boxes. Thirty subjects who participated in the questionnaire survey, were asked to provide estimates of …the perceived weights and corresponding linguistic classification of load heaviness, while lifting five pre-weighted boxes. The subjects had previously gone through another phase of the project where they had determined their maximum acceptable weight of lifting using the psychophysical approach. The perceived weights were not significantly different from the physical weights for the 'light' to 'moderate' categories of load heaviness. Furthermore, the concept of recommended weight limit (RWL) fell in the 'light' load category for which the subjects were good judges of load heaviness. The results of this study provide support for setting the lifting limits based on the RWL concept designed to reduce the risk of low back injury. Show more

Keywords: Manual lifting, load heaviness, perception, linguistic modeling, fuzzy sets

DOI: 10.3233/OER-1998-1405

Citation: Occupational Ergonomics, vol. 1, no. 4, pp. 291-303, 1998

Article Type: Other

DOI: 10.3233/OER-1998-1406

Citation: Occupational Ergonomics, vol. 1, no. 4, pp. 305-306, 1998