Occupational Ergonomics - Volume 1, issue 1

Authors: Das, Biman

Article Type: Editorial

DOI: 10.3233/OER-1998-1101

Citation: Occupational Ergonomics, vol. 1, no. 1, pp. 1-1, 1998

Authors: Mirka, Gary A. | Baker, Ann | Harrison, Angela | Kelaher, Dan

Article Type: Research Article

Abstract: The purpose of this research was to determine the impact of coupling and load magnitude on trunk dynamics during lifting activities. Subjects lifted a box that simulated three levels of coupling: good, fair and poor and seven levels of mass: ranging from 4.5-31.5 kg. The dependent variables were the peak dynamic moment generated about the lumbosacral joint and the peak vertical ground reaction forces produced during the lift. The results show that at low levels of box mass there are no significant differences in trunk dynamics and resulting peak dynamic moment across the different coupling conditions. However, when loads greater …than 13.5 kg were lifted, a change in the normal dynamics of the lifting motion was noted, but only in the poor coupling condition, indicating an interaction between load and coupling. The results of this study indicate that the role of coupling under dynamic lifting conditions has both a perceptual and biomechanical basis that need to be considered when designing manual materials handling tasks. Show more

Keywords: Biomechanics, perception, dynamic, lifting, spine

DOI: 10.3233/OER-1998-1102

Citation: Occupational Ergonomics, vol. 1, no. 1, pp. 3-11, 1998

Authors: Strasser, Helmut | Wang, Baoquiu

Article Type: Research Article

Abstract: The focus of this research was to investigate how maximum torque and muscle forces were affected by pronation and supination, i.e., inward and outward rotation of the forearm in a series of screwdriver tests with 6 varied handles. Consecutively, maximum torque for pronation and supination was determined, submaximum isometric levels of torque were demanded, and, finally, an equal dynamic screwing work for all subjects was simulated. Physiological cost of performance was simultaneously measured by registrations of electromyographic activities (EA) from 4 muscles, which were expected to be involved intensively in screwing tasks. Significant and essential differences between maximum torque values …produced by pronation and supination of the right and the left arm of the mainly right-handed subjects were found. For clockwise work, as it is necessary e.g., for driving in screws, inward rotations (pronations) of the nondominant hand are at least as strong as outward rotations of the dominant hand. Differences of about 8% favour of pronations were found. Yet, for counter clockwise work involved e.g., in removing a tightened screw, inward rotations of the dominant hand yielded a much more stronger torque strength than outward rotations of the nondominant hand. Differences of more than 50% right-handed subjects were measured. Also, EA values of the 4 muscles monitored on the right arm differed significantly. Systematically operational and physiological differences due to the varied screwdriver grips, as results of investigations which were not the main objective of the study, corresponded well with the findings of prior studies. Show more

Keywords: Pinch torque strength, electromyographic activity, dexterity, pronation, supination

DOI: 10.3233/OER-1998-1103

Citation: Occupational Ergonomics, vol. 1, no. 1, pp. 13-22, 1998

Authors: Kerk, Carter J. | Chaffin, Don B. | Monroe Keyserling, W.

Article Type: Research Article

Abstract: The stability constraints of a two-dimensional static human force exertion capability model (2DHFEC) were evaluated with subjects of varying anthropometry and strength capabilities performing manual exertions. The biomechanical model comprehensively estimated human force exertion capability under sagittally symmetric static conditions using constraints from three classes: stability, joint muscle strength, and coefficient of friction. Experimental results showed the concept of stability must be considered with joint muscle strength capability and coefficient of friction in predicting hand force exertion capability. Information was gained concerning foot modeling parameters as they affect whole-body stability. Findings indicated that stability limits should be placed approximately 37 …% the ankle joint center to the posterior-most point of the foot and 130 % the distance from the ankle joint center to the maximal medial protuberance (the ball of the foot). 2DHFEC provided improvements over existing models, especially where horizontal push/pull forces create balance concerns. Show more

Keywords: Postural stability, balance, biomechanical modeling, static exertions

DOI: 10.3233/OER-1998-1104

Citation: Occupational Ergonomics, vol. 1, no. 1, pp. 23-39, 1998

Authors: Bagchee, Angshuman | Bhattacharya, Amit | Succop, Paul A. | Emerich, Ronald

Article Type: Research Article

Abstract: The methodology described here presents quantitative measures of estimating the severity of postural instability based on the proximity and spread of body sway in relation to the basal area of support. A simplified functional basal area of support is determined based on the maximal forward reaching ability of the subject. Three non-dimensional indices for quantitating the potential of postural instability are introduced. Application of this method is illustrated through an experiment with ten healthy industrial workers performing four different tasks. The results indicate that these indices are reproducible, sensitive to task performance and can be utilized to estimate the postural …stability associated with each task. Application of this method would include the identification of factors, both intrinsic and extrinsic, that contribute to the maintenance of postural balance during task performance. Interventions can then be evaluated using this method. Show more

Keywords: Posture, balance, footprints, postural stability indices, stability, base-of-support, task performance

DOI: 10.3233/OER-1998-1105

Citation: Occupational Ergonomics, vol. 1, no. 1, pp. 41-53, 1998

Authors: Matias, Aura C. | Salvendy, Gavriel

Article Type: Research Article

Abstract: A total of 100 female VDT operators, who performed a variety of office functions, were studied at a major midwestern university. The purpose of this study was to determine the effects of job exposure, posture, psychosocial and personal factors on carpal tunnel syndrome (CTS) comparing between CTS and non-CTS subjects. The results of the study suggest that the main causation of CTS are long periods of continuous typing activity, static and bent postures of the wrist, seating posture and the individual's wrist size. It was found that CTS subjects spent longer time and a greater proportion of their work involving …keyboarding than the non-CTS subjects. CTS subjects tended to assume more extended and deviated wrist postures as well as forward leaning seating postures than the non-CTS subjects. Furthermore, non-CTS subjects were found to have wider wrists than the CTS subjects. Show more

Keywords: Carpal tunnel syndrome, video display terminal, cumulative trauma disorders, job design, posture, anthropometry

DOI: 10.3233/OER-1998-1106

Citation: Occupational Ergonomics, vol. 1, no. 1, pp. 55-66, 1998

Authors: Aghazadeh, Fereydoun | Waly, Sherif M. | Santoso, Dedik S.

Article Type: Research Article

Abstract: Regression models were developed to predict the maximum acceptable weight of lift (MAWL) for Indonesian population based on anthropometric and job related variables. Job related variables including lifting frequency, lifting height, and vertical distance of lift and 16 anthropometric variables were used in this study. A comparison between the MAWL obtained from this study, NIOSH RWL and the predicted MAWL of U.S. workers were conducted. RWL were much lower than the MAWL for both Indonesian and U.S. workers. Also, the Indonesian workers had higher MAWL compared to the U.S. population.

Keywords: Lifting load, anthropometry, Indonesian workers, job-related variables

DOI: 10.3233/OER-1998-1107

Citation: Occupational Ergonomics, vol. 1, no. 1, pp. 67-74, 1998

Article Type: Other

DOI: 10.3233/OER-1998-1108

Citation: Occupational Ergonomics, vol. 1, no. 1, pp. 75-80, 1998