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- Volume 24, Issue 2, 2012
Ergonomics SA : Journal of the Ergonomics Society of South Africa - Volume 24, Issue 2, 2012
Volume 24, Issue 2, 2012
Author Candice ChristieSource: Ergonomics SA : Journal of the Ergonomics Society of South Africa 24 (2012)More Less
This issue of Ergonomics SA marks the end of the journal's 23rd year of scholarly publication. The journal was first published in January 1989 and between then and now,the journal has made a substantial contribution to the discipline particularly with respect to Ergonomics in Industrially Developing Countries (IDC). We continue to attract good quality submissions from around the IDC globe supporting our research base. We also strive to maintain high scientific standards and have a rigorous peer review system in place.
Development of a modular test stand for the measuring of dynamic muscular strain of test persons for the simulation in digital human modelsSource: Ergonomics SA : Journal of the Ergonomics Society of South Africa 24, pp 2 –17 (2012)More Less
In order to evaluate the human's dynamic physical strain during work, for example during assembly work, an evaluation library of all executions carried out by humans is needed. Therefore, necessary measurements of muscular strains via electromyography have to be carried out which require standardized and repeatable external stresses,warranted by a test stand. Both the methods and the single development steps of the planning and dimensioning process of such a test stand are explained. After the general construction methodology, requirements to the test stand were made concerning the functional structure and the active principle of every single test stand components. Calculations and dimension by means of CAD programs as well as results from early tests and both spatial and financial determining factors were integrated into the modularly planned and assembled test stand, which can be used for many different movements of the human body. In addition to the realized solution approach, alternative solutions are presented.
The point prevalence of work-related musculoskeletal pain among general surgeons in KwaZulu-Natal, South AfricaAuthor F.A DesaiSource: Ergonomics SA : Journal of the Ergonomics Society of South Africa 24, pp 18 –30 (2012)More Less
During surgery, surgeons experience substantial stress to the musculoskeletal system. The proposed mechanism of such stress has been attributed to a large number of ergonomic variables. The aim of this study was to investigate the point prevalence of musculoskeletal pain and its predisposing mechanism of injury among general surgeons in the South African. Seventy six general surgeons participated in an occupational, epidemiological, retrospective study, voluntarily. Biographical and kinanthropometric measurements, occupational and musculoskeletal information were gathered using a self-report questionnaire (n=76). Descriptive statistical analysis (mode, mean, frequency, percentage) and inferential statistics (chi-square) were employed to analysisthe data with the level of significance set at 0.05. According to the results, 69.74% of the cohort experienced musculoskeletal pain in one or more anatomical location/s (n=53; p<0.001) of which lower back pain (60.38%) was the most prevalent (X2 (N=76) = 0.021 p<.05). The majority (n=76) of the cohort opted for standing posture with prolonged, sustained cervical, vertebral, glenohumeral and elbow flexion during surgical procedures Preference to stand (n=76) or remain seated (n=71) during a surgical procedure is postulated to be a non-protective factor against experiencing musculoskeletal pain as both these portions of the cohort experienced a similar prevalence of musculoskeletal pain (69.73% vs. 67.61%; p>0.05). Collectively the ergonomic choices made by the cohort deviated from the normal anatomical standing position as outlined by Kendall in 1983, for prolonged periods of time, thereby escalating postural load, propagating musculoskeletal pain.
The effects of task familiarity on performance and strain during a self-paced lifting and lowering taskAuthor L. LeeSource: Ergonomics SA : Journal of the Ergonomics Society of South Africa 24, pp 31 –43 (2012)More Less
The concept that self-selected work-rest scheduling and pacing can be an effective tool to prevent fatigue build-up, and therefore overexertion injuries, is relatively unexplored in the literature. Despite the increase in automation in the workplace and forced work pace as a result, there are still many jobs that allow workers to select their own work pace and rest breaks. Numerous factors, such as task familiarity influence a worker's work-rest scheduling. This study is aimed at determining the effects of task familiarity on work-rest scheduling, physiological and subjective strain, as well as work performance in a self-paced lifting and lowering task. Twelve healthy and moderately fit female university students, between 18 and 25 years of age, participated in this study. Participants were required to attend four sessions during which they lifted and lowered a 10 kg crate 120 times at a self-selected work rate, resting whenever and for as long asthey needed. The first session was set as the "unfamiliar" condition. This was followed by two familiarization sessions to ensure that the participants were accustomed to thetask in the last session, set as the "familiar" condition. Work-rest scheduling data, heart rate, electromyographical data, subjective exertion responses and work rate weremeasured during the "unfamiliar" and "familiar" conditions. No data were collected during the second and third sessions. The results showed that task familiarity resulted in significantly (p<0.05) shorter overall working time due to less rest breaks and shorter rest break durations, while overall performance, such as lifting rate, increased.Significant reductions in physiological and perceptual strain were also evident from lower heart rates, EMG responses of the erector spinae, and central and local ratings of perceived exertion under the "familiar" condition.
Source: Ergonomics SA : Journal of the Ergonomics Society of South Africa 24, pp 44 –57 (2012)More Less
The purpose of the study was to examine the relationship between physical fitness measures and job performance in fire-fighters. Forty-eight experienced, professionalfire-fighters (29 ± 5.8 years) participated in fitness and job performance testing sessions each spaced a week apart. Analysis was performed using Pearson moment correlation coefficients and multiple linear regression with alpha set at p≤.05. Significant correlations (p≤ .01) were found between a job performance task (Revised Grinder) and the following: lean muscle mass (r = -.69), overall fitness (r = -.62), height (r = -.62), strength endurance: deadlift (r = -.54), bent-over row (r = -.51), bench press (r = -.51), shoulder press (r = -.46); maximal strength: hand grip strength (r = -.57), bench press (r = -.51), anaerobic capacity: 400m (r = .50), and aerobic capacity: multistage shuttle run (r = -.46). Multiple linear regression determined that lean muscle mass and aerobic capacity account for 82% of the variation in the job performance task. Conclusion: Firefighting taxes virtually all aspects of physical fitness. These data help the exercise specialist choose appropriate tests to assess fire-fighters and new recruits, as well as prescribe specific fitness programs for fire-fighters.
Ergonomic intervention for reducing the exposure to musculoskeletal disorders risk factors in pharmaceutical production centreAuthor Y RodriguezSource: Ergonomics SA : Journal of the Ergonomics Society of South Africa 24, pp 58 –75 (2012)More Less
The present study was conducted in a packing line at a pharmaceutical production centre, where improvement of existing working conditions was required through the redesign of workplaces. The three workplaces selected were: packing, stamping and baling. The RULA and Strain Index ergonomic tools were employed to evaluate the risks of developing MSDs. According to RULA the highest risk corresponds to right and left side of the baling operation (score of 7 and 6 respectively), while Strain Index classifies both sides of stamping as hazardous (strain index of 13.5 for both) as well as the left side of the baling operation (strain index of 12). The risk associated with these workplaces indicates the need for immediate ergonomics intervention. The main elements of redesign consisted of foot rests, tables with a box containing packing materials, belt conveyors, industrial chairs and the plant layout. Anthropometric data from the Cuban population were used to determine optimal workplace dimensions,while the limiting criterion was based on women. A digital manikin was used to combine all selected design values in order to ascertain if they were compatible. Furthermore, a 3D modeling technique was utilized and workers participated in brainstorming sessions. The intervention is an example of proactive approach to enhancing worker's health.