Occupational Ergonomics - Volume 10, issue 1-2

Authors: Handrigan, Grant A. | Power, Geoffrey A. | MacKinnon, Scott N. | Basset, Fabien A.

Article Type: Research Article

Abstract: Purpose: The purpose of this study was to investigate the biomechanical characteristics and physiological cost of three standardized pulling tasks. 12 female and 17 male subjects participated in the study. The subjects were instructed to pull a load at three different heights (hip, shoulder, eye – anatomical landmarks defined the end of a pull) at a rate of ten pulls per minute, for a period of ten minutes (one hundred total pulls). The pulls were sub-maximal and chosen to represent a task during a typical 8 hour workday. Statistics: ANOVA statistical analyses with Bonferroni pairwise comparisons were performed …to determine significance. Results: Statistical significance was obtained for energy expenditure (Ė), sagittal displacement and twisting velocity. Hip pulling Ė was lower than shoulder pulling Ė (p=0.046) and eye pulling Ė (p=0.002) by 7% and 11%, respectively. Hip pulling involves less sagittal displacement than shoulder (p=0.004) and eye (p=0.001) by 37% and 46%, respectively. Finally, twisting velocity at hip (p=0.042) and shoulder (p=0.006) pulling were 30% and 36% higher than twisting velocity at eye pulling. Conclusion: Physiological data combined with biomechanical data provide a comprehensive description of the demands associated with this standardized pulling task. This combined information assists in risk factor identification and intervention design for tasks involving repetitive upper limb movements. Show more

Keywords: Pulling, energy expenditure, trunk kinematics, repetitive motion, fatigue

DOI: 10.3233/OER-2011-0188

Citation: Occupational Ergonomics, vol. 10, no. 1-2, pp. 1-11, 2011

Authors: Chopp, Jaclyn N. | Hunt, Shannon | McKean, Chris | Dickerson, Clark R.

Article Type: Research Article

Abstract: Installation of electrical meters is an occupational task that may place utility employees at risk of upper extremity discomfort or disorders. This study focused on identifying the most preferable installation technique from several alternatives using a combination of professional utility employees and experimental subjects. Factors considered included variation in installation height, the use of a hand-held mallet, lubrication applied to the meter and the use of one vs. two hands for installation. Installing meters located above shoulder height resulted in a two-fold increase in both peak and cumulative hand acceleration and pressure. Further, the use of a force-absorbing striking mallet …showed significantly lowered peak pressure (60%) compared to other techniques. Peak acceleration and cumulative pressure were significantly lower than other techniques for both experienced and inexperienced subjects when using the mallet. Additionally, the mallet installations had amongst the lowest ratings of perceived exertion across installation types. Thus, the primary recommendations for meter installation with respect to the analyzed scenarios are to use a force-absorbing striking mallet and avoid installations at high locations. Show more

Keywords: Hand acceleration, pressure distribution, striking, electrical meter installation

DOI: 10.3233/OER-2011-0189

Citation: Occupational Ergonomics, vol. 10, no. 1-2, pp. 13-24, 2011

Authors: Das, Banibrata | Gangopadhyay, Somnath

Article Type: Research Article

Abstract: Seventy five rice cultivators and seventy five control subjects were selected randomly from the villages of West Bengal, India, to evaluate musculoskeletal disorder, thermal stress, physiological stress among the rice cultivators. Modified Nordic questionnaire studies and posture analysis were performed among them by Ovako Working Posture Analyzing System. Thermal and physiological stresses were also assessed by measuring WBGT index and heart rates respectively. All of the subjects suffered discomfort at different parts of the body especially at lower back (99%), knee (91%), ankle (83%), feet regions (68%).The lung function values FVC (3.24), FEV1 (2.56), FEV1 /FVC ratio (79.57), PEFR …(412.0) of the rice farmers were much lower than the control group due to inhalation of dust particles in the rice fields. They also suffered from thermal (36°C) and physiological stress due to hazardous working condition and increased heart rates (148 beats/min). Thus their health and overall work performance were affected. Show more

Keywords: Ovako Working Posture Analyzing System, musculoskeletal disorder, physiological stress, thermal stress, lung function values

DOI: 10.3233/OER-2011-0190

Citation: Occupational Ergonomics, vol. 10, no. 1-2, pp. 25-38, 2011

Authors: Murphy, Taylor Andrew | Oliver, Michele Lea

Article Type: Research Article

Abstract: The submaximal, constrained nature of joystick manipulation makes it difficult to select an appropriate technique for upper limb electromyography (EMG) normalization. The purpose of this study was to determine an appropriate submaximal isometric normalization method to quantify EMG from shoulder muscle activation in hydraulic-actuation joystick operators that could later be implemented in field settings. Surface EMG data were collected from the upper trapezius, posterior deltoid, and anterior deltoid of seventeen subjects while operating a hydraulic-actuation joystick. EMG data were normalized using two techniques: muscle specific (mRVC) and task specific (three joystick positions: start-tRVCStart , middle-tRVCMiddle and end-tRVCEnd ). No …significant differences (p ⩽ 0.05) were observed for intersubject coefficient of variation (CV) between normalization procedures (mRVC, tRVCStart , tRVCMiddle tRVCEnd , un-normalized). These equivocal findings do not favour the use of any one of the submaximal normalization procedures over another. However, though not statistically significant, the un-normalized (0.68 ± 0.15) CVs were lower than those of normalized ensembles (0.96 ± 0.24) suggesting that for constrained, submaximal tasks, it may not be necessary to normalize EMG. Although this analysis was applied to upper limb EMG during joystick manipulation, the results have potential application to other submaximal upper limb tasks which are constrained and repetitive in nature thus including many assembly line jobs. Show more

Keywords: EMG, normalization, hydraulic-actuation joysticks, shoulder loading

DOI: 10.3233/OER-2011-0191

Citation: Occupational Ergonomics, vol. 10, no. 1-2, pp. 39-52, 2011

Authors: Okunribido, Olanrewaju O. | Wynn, Tony | Lewis, David

Article Type: Review Article

Abstract: The purpose of this review was to examine the evidence for age/ageing as a risk factor for musculoskeletal disorders (MSD) in the workplace. Studies about MSD among worker populations (published after 2001) were reviewed if they focused on MSD as an occupational problem, included older workers (aged 50 years and above) in the study population, compared outcomes between young (25 years old or less) and older workers, and/or examined the work-relatedness of musculoskeletal disorders (including symptoms and outcomes). Evidence suggested that older workers are more susceptible to MSDs than young workers. However, the propensity for injury of older workers in …the workplace depends more on the difference between the demands of work and the worker's physical work capacity rather than their age. An older workforce has implications for the health and safety responsibilities of employers, such as providing additional support for workers' needs, and changing the workplace attitudes towards ageing. Show more

Keywords: Older workers, young workers, musculoskeletal disorders, risk factors

DOI: 10.3233/OER-2011-0192

Citation: Occupational Ergonomics, vol. 10, no. 1-2, pp. 53-68, 2011