Occupational Ergonomics - Volume 4, issue 2

Authors: Strasser, Helmut

Article Type: Editorial

DOI: 10.3233/OER-2004-4201

Citation: Occupational Ergonomics, vol. 4, no. 2, pp. 71-72, 2004

Authors: Strasser, Helmut | Kluth, Karsten | Keller, Erwin

Article Type: Research Article

Abstract: Electromyography enables the measurement of the intensity of muscle exertions which are demanded when working with hand-held tools and controls as well as when performing repetitive manual movements. Utilizing multi-channel recording devices, comprehensive physiological responses of working muscles can be quantified in figures and numbers, whereby more or less ergonomically designed tools lead to different physiological costs in terms of muscle strain associated with work. A computer-based system was developed for the suitable application of electromyography, a technique which requires differentiated and detailed knowledge of the possibilities and limitations as well as a substantial amount of experience. Software packages provide …programs for the recording, analysis, and evaluation of myoelectric data. Knowledge about practical methods of appropriate recording and processing of myoelectric data which has been accumulated and further developed during the last decade has been fed into the program system. The same is true for a set of investigations already carried-out and published. Making use of the specifically developed and well-proven software packages which can be loaded into almost all PCs for recording, analyzing, and standardizing electromyographic data, even a user who until now is less familiar with these tasks gains access to electromyography as an efficient and important ergonomic method which is applicable with reasonable expenditure both in the laboratory and in the field. Show more

Keywords: multi-channel electromyography, computer-based system, hand-held tools, physiological costs

DOI: 10.3233/OER-2004-4202

Citation: Occupational Ergonomics, vol. 4, no. 2, pp. 73-87, 2004

Authors: Kluth, Karsten | Pauly, Olaf | Keller, Erwin | Strasser, Helmut

Article Type: Research Article

Abstract: Firefighters are subject to high physical and psychological stress and fire fighting often requires mastering complicated tasks under adverse conditions. In this job, the handling of the hose/nozzle combination is a central and often performed task. The objective of this field study was to ergonomically evaluate different designs of 3 fire nozzles – a multi-purpose nozzle according to a German standard, a pistol nozzle (AWG), and a supposedly ergonomic nozzle (Quadrafog) – with respect to the muscle strain associated with performing standardized working tests. Eleven firefighters (10 males and 1 female, aged 27–54) used the 3 nozzles in the practice …area of a fire station. For 3 different working tasks (straight stream, wide fog, and alternating operation), electromyographic activity was monitored continuously from 7 muscles of the right and left hand-arm-shoulder system using a PC-based mobile data registration system. Specially developed questionnaires provided subjective assessments of the ergonomic quality of the fire nozzles. The standard nozzle – which is still very frequently used – is only suited for "water go" for extended periods of time, but not for dynamic work. Especially the nozzle operator's arm musculature is subjected to high strain by the hose forces, which depend on water pressure and flow. AWG and Quadrafog led to substantially lower overall strain and smaller static components. Only in pure straight stream fire fighting was there no difference between the standard nozzle and the other models. High static portions characterize straight stream as well as wide fog operation. Both operations required small movements of the body so that the static portions became more noticeable. Overall, the AWG fire nozzle exhibited the most balanced strain profile with non-critical static values and a tolerable overall strain for alternating operations. These results are in accordance with the fire fighters' subjective preference for this model. It is unfortunate that currently the sole focus remains still on the price rather than the usability, which determines the physiological costs that must be paid by the operator. In the future, more attention should be paid to the compatibility between the characteristics of the human organism and the technical components of the tool. Show more

Keywords: field studies, fire nozzles, allegedly and proven ergonomic quality, electromyographic assessment, subjective ratings

DOI: 10.3233/OER-2004-4203

Citation: Occupational Ergonomics, vol. 4, no. 2, pp. 89-104, 2004

Authors: Strasser, Helmut | Fleischer, René | Keller, Erwin

Article Type: Research Article

Abstract: Manufacturers of ergonomic split keyboards promise maximum effectiveness and comfort as well as a reduction of physical complaints. In order to determine the positive effects claimed, a study was carried out during which 10 male subjects (Ss) participated in standardized working tests. They entered text into a PC, alternatingly using a conventional keyboard and an ergonomic keyboard. Electromyographic activity (EA) of 8 muscle groups was simultaneously recorded during altogether 6 working phases with a duration of 10 min, each. Measurements of the maximum activity, EAmax , via maximum voluntary contractions of the 8 muscles – which were necessary for calculating …standardized electromyographic activity (sEA) used to represent muscle strain as a percentage – were always taken at the end of the experiment. Muscle strain varied from muscle to muscle but the level of the sEA-values for the different muscles was reproducible and stable. Also, activation of most muscles acting on the shoulder, upper arm, forearm, and the hand showed differences which, though small in amount, could be statistically secured and associated with the keyboard type. The ergonomic design of the tested keyboard led to objectively verifiable and plausible reductions of muscle strain. Show more

Keywords: conventional and ergonomic keyboards, standardized working tests, multi-channel electromyography, muscle strain

DOI: 10.3233/OER-2004-4204

Citation: Occupational Ergonomics, vol. 4, no. 2, pp. 105-119, 2004

Authors: Keller, Erwin | Fleischer, René | Strasser, Helmut

Article Type: Research Article

Abstract: At an ergonomically optimized VDU-workstation, a group of 10 test subjects (Ss) carried out a typing task both at the test keyboard and a reference computer keyboard. The participants' personal subjective assessments concerning the working conditions with the two keyboards and the layout of the ergonomic model were recorded via specially designed questionnaires. These were given prior to, and after, the working tests and, therefore, reflected ratings without and with working experience. The posture of the hand, the lower and the upper arm, and the shoulder during text input were evaluated quite differently as a consequence of using the two …keyboards. The working posture associated with the conventional keyboard was never assessed positively. The ratings always reached positive values when operating the ergonomic model. The handling of the keyboard and the overall impression were also in favor of the test keyboard as a result of the working tests. Comfort and effort while typing at the keyboards also differed substantially and were in favor of the test keyboard. The same was true for altogether 10 items of the questionnaire, aiming at evaluation of details of the ergonomic keyboard and its overall appearance. Show more

Keywords: questionnaire, body posture evaluation, comfort and effort, complaints associated with typing

DOI: 10.3233/OER-2004-4205

Citation: Occupational Ergonomics, vol. 4, no. 2, pp. 121-131, 2004

Authors: Kluth, Karsten | Kellermann, Horst G. | Strasser, Helmut

Article Type: Research Article

Abstract: In a comparative investigation 3 file handles were evaluated with regard to their ergonomic quality. By means of a mobile measuring system for the recording of peripheral-physiological data, the muscle strain of 9 muscles of the left and right hand-arm-shoulder system was quantified with surface electromyography. A special laboratory device facilitated the standardized execution of the tests. A specific bipolar questionnaire had enabled the subjective assessment of the design, surface material, general usability, avoidance of pressure marks and blisters, suitability for the exertion of the necessary pressure and pushing forces, and the suitability during hand perspiration. Also, the assessment of …more or less favorable body positions to various filing directions was made. From substantial differences in the objective data and the subjective evaluation, the inference has to be drawn that only the combination of subjective surveys and objective measurements represent the opportunity to assess the ergonomic quality of working tools adequately. Show more

Keywords: product ergonomics, electromyography, subjective assessment, hand tools

DOI: 10.3233/OER-2004-4206

Citation: Occupational Ergonomics, vol. 4, no. 2, pp. 133-142, 2004