Occupational Ergonomics - Volume 12, issue 1-2

Article Type: Editorial

DOI: 10.3233/IP-150221

Citation: Occupational Ergonomics, vol. 12, no. 1-2, pp. 1-2, 2015

Authors: Penzkofer, Mario | Henke, Anna | Kluth, Karsten

Article Type: Research Article

Abstract: BACKGROUND: Screwdrivers are a standard tool in all metal and wood processing jobs. To prevent work-related injuries in the upper extremities, an ergonomic and safe design of the tool is indispensable. OBJECTIVE: In this comparative ergonomic study, the ergonomic quality of various screwdriver handles from European manufacturers, which exhibited decisive differences in the design aspects ``shape'', ``dimension'', ``material'' and ``surface'', was tested. METHODS: Twenty-one male right-handed test subjects had to carry out different screw-driving tests. Before and after the tests, the subjects had to assess specific criteria of the handles such as handling, …design features and material. Furthermore, they were asked to express potential physical complaints in the fingers, hand and forearm with respect to intensity and occurrence. In order to reveal possible model-specific differences in operational performance and in muscle strain, maximum exertable torque measurements were carried out, and the associated electromyographic activity (EA) of four muscles involved in different screw-driving tasks was measured via surface electromyography. RESULTS: The results from the determined EA data and the users' subjective perceptions while handling the screwdrivers, showed a great impact of the design features ``shape'', ``dimensions'', ``material'' and ``surface''. CONCLUSIONS: Only those screwdrivers designed according to appropriate ergonomic criteria enable a high operational performance with reduced physiological costs that have to be paid by the muscles. Show more

Keywords: Hand-held tools, electromyographic activity, subjective assessments, physiological responses

DOI: 10.3233/OER-150220

Citation: Occupational Ergonomics, vol. 12, no. 1-2, pp. 3-18, 2015

Authors: Groos, Sandra | Kluth, Karsten

Article Type: Research Article

Abstract: BACKGROUND: So far, there exists no internationally uniform regulation about the pressure limits of water used for putting out fires in multi-story buildings and large properties. OBJECTIVE: In this ergonomic study, the optimum and maximum pressure for the fire water supply was tested with respect to physically feasible and safe indoor fire-fighting. METHODS: In order to prove whether the nozzles work most efficient and a fire can be extinguished safely and precisely, 12 professional fire-fighters carried out simulated fire-fighting procedures under nearly realistic conditions. Throughout the entire test, the electromyographic activity (EA) from 7 …muscles of the right hand-arm-shoulder system and one muscle of the left arm was recorded. Additionally, a special questionnaire had to be filled in to evaluate the subjective experiences when handling the nozzles. RESULTS: The EA - standardized through MVCs (Maximum Voluntary Contractions) - exceeded the limit for short-term static work for 3 muscles, especially when the pressure was 0.8 MPa and higher. The subjective ratings confirmed the measured physiological responses. CONCLUSIONS: The operating pressure for the fire water supply should not exceed 0.6 MPa (as compromise 0.7 MPa), in order to ensure safe and precise fire-fighting, and that the nozzles work most efficient. Show more

Keywords: Fire-fighting, electromyography, subjective assessment, physiological responses, muscular strain, hand-arm-shoulder system

DOI: 10.3233/OER-150218

Citation: Occupational Ergonomics, vol. 12, no. 1-2, pp. 19-31, 2015

Authors: Kluth, Karsten | Keller, Erwin

Article Type: Research Article

Abstract: BACKGROUND: The positioning of the hand-arm-shoulder system while computer-aided data entry, text processing or mouse operations - due to the kinematical chain's own weight - represents an important risk factor for musculoskeletal complaints such as RSI syndrome as well as PC-work-induced carpal tunnel syndrome. OBJECTIVE: A new system to control the mouse cursor by a rollerbar promised beneficial support and a more comfortable working with a standard keyboard. METHODS: Twenty-four subjects, classified by gender and age, participated in standardized working tests to proof the ergonomic quality of the rollerbar mouse. The hypothetically expected relief …of the hand-arm-shoulder muscles was measured via electromyographic methods. Subjective assessments based on the work experiences were obtained in order to enhance the evaluating of the product's ergonomic quality. RESULTS: The rollerbar system was rated more favorably than the standard mouse. There are some differences along age and gender lines with regard to the strength of preference, but the rollerbar was the unequivocally preferred input device. Unfortunately, the results of the electromyographic measurements do not support as strong an endorsement for either of the two products. The reason is that the level of physical strain during the working tests was simply not high enough. CONCLUSION: The rollerbar mouse could be confirmed as an ergonomically promising product. Show more

Keywords: Computer input device, electromyography, subjective assessment, muscular strain, hand-arm-shoulder system

DOI: 10.3233/OER-150219

Citation: Occupational Ergonomics, vol. 12, no. 1-2, pp. 33-48, 2015

Authors: Serafin, Patrick | Muehlemeyer, Christoph | Levchuk, Inna | Lang, Karl-Heinz | Gebhardt, Hansjuergen | Klussmann, André

Article Type: Research Article

Abstract: BACKGROUND: For the ergonomic design of products and workplaces, knowledge about e.g. the physical strength or hand preference of the target population is helpful. OBJECTIVE: The aim of this study was to gather data about isometric hand force and hand preference of a large sample of the population in Germany. METHODS: The isometric maximum force was determined in one-handed pulling (with support for the other hand), gripping and handling a screwdriver (supination) for both hands. Other factors such as age, gender, hand preference and occupation were documented in a standardized questionnaire. RESULTS: …1,207 (428 female, 779 male) subjects between 5 and 91 years participated in this study. On average, females reach 2/3 of the strength level of males. The results do not show any significant influence of age on the maximum isometric force in the age groups between 20 and 59 years, but high intra age group differences occur. CONCLUSIONS: On average, for all subjects the preferred hand is stronger. The difference between the dominant and the subdominant hand ranges between 1% and 11% on average depending on the type of force exertion, hand preference and gender. Nevertheless, a very large variation of the side differences and strength levels within the types of handedness exists. Show more

Keywords: Physical strength, age, gender, hand preference

DOI: 10.3233/OER-150222

Citation: Occupational Ergonomics, vol. 12, no. 1-2, pp. 49-59, 2015

Authors: Gebhardt, Hansjürgen | Mühlemeyer, Christoph | Lang, Karl-Heinz | Klussmann, Andre | Schlutter, Beate | Vomberg, Anja

Article Type: Research Article

Abstract: BACKGROUND: Standardized test fingers are used for testing products against mechanical and electrical hazards. The dimensions of the most common test finger, mentioned in several standards, have remained unchanged for many decades. In the meantime, the corresponding anthropometric dimensions of the human being as well as the safety standard and safety awareness have changed. OBJECTIVE: Starting from the dimensions of the most common test finger for adult persons, length and diameter of the test finger were analysed, whether they are still in accordance with the anthropometric considerations and whether they represent a sufficient safety-level. METHODS: …Current distributions of relevant body dimensions from literature and own measurements were considered and compared with the dimensions of the common test finger. RESULTS: The analysis of anthropometric data reflects that in the past decades people are on average getting larger and wider. This refers to the German and European population, but also to large other parts of the world's population. CONCLUSIONS: The current diameter of the common test finger still offers a high level of protection. However, the changes of the last decades, both in what concerns the anthropometric measurements as well as the safety standard and safety awareness, seems to require an adaptation of the length of the test finger to ensure the same level of safety protection as the chosen diameter. Show more

Keywords: Product testing, test finger, anthropometry, electrical hazards, mechanical hazards, safety

DOI: 10.3233/OER-150223

Citation: Occupational Ergonomics, vol. 12, no. 1-2, pp. 61-69, 2015