Occupational Ergonomics - Volume 3, issue 1

Authors: Das, Biman

Article Type: Editorial

DOI: 10.3233/OER-2003-3101

Citation: Occupational Ergonomics, vol. 3, no. 1, pp. 1-1, 2003

Authors: Mientjes, Martine I.V. | Norman, Robert W.

Article Type: Research Article

Abstract: Effects of lumbar spine curvature on reducing risk factors for reporting low back pain (LBP) at work were assessed for a "light" but repetitive simulated workplace assembly job. Nine women stood at a target trunk angle of 30° and assembled plastic toys on a table for 25 minutes in one minute work cycles, at a work/recovery ratio of 55/5 seconds. Flexed (rounded back) postures, often observed in industry, and lordotic (hollow back) postures maintained by back extensor muscles and proposed to reduce risk by reducing shear forces, were studied. Spinal loading was imposed by torso weight only. Twenty-five minutes of …this simulated job produced discomfort scaled as "strong" to "very strong" regardless of spinal posture. Lordosis required median EMGs of 15% MVC. Flexed postures lowered back extensor EMG to as little as 5% MVC but not to zero. This apparently "light" job seems to expose people to quite high risk of reporting LBP (estimated at about 80%), mainly because of high cumulative spine loads, regardless of the spinal posture adopted. Show more

Keywords: back pain, posture, repetitive work, women, risk factors, ergonomics

DOI: 10.3233/OER-2003-3102

Citation: Occupational Ergonomics, vol. 3, no. 1, pp. 3-17, 2003

Authors: Strasser, Helmut

Article Type: Research Article

Abstract: Fundamental knowledge of anthropometric dimensions and biomechanical properties, of the capacities, as well as limitations, of the human sensory organs and the hand-arm system, i.e., comprehensive work-physiological knowledge of the characteristics of the human organism, always was, and will still in the future remain, a prerequisite for the truly ergonomic design of workplaces and work tools. Especially in Germany, work physiology represents the nucleus of today's work science or ergonomics. Besides the tasks and objectives of work physiology in ergonomics education, the principles of work-physiological research approaches are described. When evaluating workplaces and work tools, measuring physiological cost which the …organism or the organs have to pay must be quantified. Similar to heart rate increases above the resting level associated with whole-body dynamic muscle work, the physiological cost of the muscles involved in repetitive manual movements, and the operating of hand-held tools or computer input devices can be measured via multi-channel electromyography. Physiological costs of sound exposures can be quantified in temporary hearing threshold shifts and their restitution, and physiological cost to the eyes is represented, for example, in varying levels of accommodation, adaptation, and fixation. Thinking in terms of physiological cost of work guarantees safe guidance in order to achieve human-oriented working conditions. According to recent developments in acts, ordinances, directions, and regulations in Europe, ergonomics has gained a high rank, but successful ergonomic interactions depend on comprehensive knowledge and experience, and require core competency in work-physiology as well as in ergonomics work design. Show more

Keywords: work physiology, ergonomics, research and education, future challenges, physiological costs associated with work

DOI: 10.3233/OER-2003-3103

Citation: Occupational Ergonomics, vol. 3, no. 1, pp. 19-44, 2003

Authors: Karwowski, Waldemar | Mattila, Markku | Quesada, Peter M. | Kwon, Young-Guk | James, David

Article Type: Research Article

Abstract: This study examined the effect of hammer design parameters on task performance, operator physiological responses, perceived rate of exertion, task completion time, task accuracy, and user preference for hammering in the vertical (wall) and horizontal (bench) surface orientations. Two hammers used in the study differed with respect to their weight and softness of the handle grip. Ten male subjects participated in the laboratory experiment. The results showed that hammer design differences affect hammering task performance and perceived physical exertion. In general, the horizontally-oriented hammering task was faster than vertically-oriented hammering. However, task accuracy (i.e. number of nails hammered straight) was …not statistically different with respect to either hammering orientation or hammer design. Subjects identified handle design, weight, and hammer mass distribution as critical factors that affect hammering task performance. Show more

Keywords: hammer design, hammering surface orientation, task performance

DOI: 10.3233/OER-2003-3104

Citation: Occupational Ergonomics, vol. 3, no. 1, pp. 45-54, 2003

Authors: MacKinnon, Scott Netson | Stone, Gareth Wesley

Article Type: Research Article

Abstract: This study examined the effects that specific postures had on the neuromuscular activities of four muscles during an isoinertial pulling task. Ten male subjects volunteered to execute one-handed pulls at 15% of their body mass, at a frequency of 12 pulls per minute, for a duration of 12.5 minutes in both a standing and sitting posture. Electromyographical (EMG) activities of the posterior deltoid, trapezius, latissimus dorsi and erector spinae (L 4 /L 5 level) were recorded by a portable data collection system using bipolar surface electrode configurations. Collected EMG data were subsequently analysed for differences in magnitude and rate …of fatigue between conditions. Heart rates were also recorded for both conditions. Cardiovascular and neurophysiological responses provided no evidence of fatigue due to the execution of the task, suggesting that these workload and postures would be suitable for industrial applications. Analyses revealed significant differences between conditions in the level of activation for all muscles except the trapezius, suggesting that muscle recruitment is highly influenced by posture during common pulling activities. These findings support a conclusion that an operator performing repetitive submaximal (i.e. less than 15% of a subject's absolute body mass) pulling tasks would benefit from a workstation designed to accommodate standing and sitting postures in order to vary the manner in which agonist muscles are recruited. Show more

Keywords: pulling, sit and stand, EMG, fatigue

DOI: 10.3233/OER-2003-3105

Citation: Occupational Ergonomics, vol. 3, no. 1, pp. 55-64, 2003

Authors: Quintana, Rolando | Alonso, Jose A.

Article Type: Research Article

Abstract: The effects of lack of equipment adjustability on nominal ranges of motion of upper body limbs for industrial sewing operations were studied, with a particular focus on Mexican-American males. Key upper body-segments of an industrial sewing operation were marked and analyzed using cinematography for a random pool of male workers descending from northern Mexico. Experimental results revealed that the worker's posture was affected by the adjustability of the sewing equipment, which was designed for the 5th to the 95th percentile of the US population. The awkward postures in turn affected the mean angular range of motion for the body-segments studied. …As a result, there was a significant percentage of the available pool of worker's that may face occupational disorders, in spite of the fact that the equipment is adjustable, albeit from the 5th to the 95th percentile of the US population. These findings are particularly important to companies whose workforce is predominantly from populations that do not fit the US population profile. An adjustability index tool was developed as an equipment purchase/design tool that quantifies the percentage of the available pool of workers at risk of occupational disorders due to improper postures resulting from lack of adjustability. Finally, a cost framework is presented for choosing equipment that minimizes internal and external costs associated with equipment adjustability. Show more

Keywords: Mexican-American population, anthropometry, equipment adjustability, work design, work evaluation

DOI: 10.3233/OER-2003-3106

Citation: Occupational Ergonomics, vol. 3, no. 1, pp. 65-80, 2003

Article Type: Calendar

DOI: 10.3233/OER-2003-3107

Citation: Occupational Ergonomics, vol. 3, no. 1, pp. 81-81, 2003