Occupational Ergonomics - Volume 9, issue 1

Authors: Venkata, Bharat Kumar Bhallam | Aghazadeh, Fereydoun | Rajulu, Sudhakar L. | Sweet, Robert

Article Type: Research Article

Abstract: This study examines the effect of an overhead drilling support and position of the arm on muscular activity of the shoulder. Root mean square amplitude (RMS) of the EMG activity from dominant side anterior deltoid, bicep and trapezius muscles was used to determine the load on the muscular system. The participants used a subjective rating scale to evaluate the overhead support stand and holding position. The results demonstrate that the overhead support stand was effective in reducing the muscular load. The mean RMS value reduction with overhead support stand, when compared to the without support in bicep muscles during near, …middle and far reach positions were 18%, 24% and 47%, respectively. For anterior deltoid muscles the percentage decrease in mean RMS values for near, middle and far reach positions were 24%, 33% and 49%, respectively; and for trapezius muscles the percentage decrease in mean RMS values during near, middle and far reach positions were 32%, 33% and 42%, respectively. The middle reach position, in contrast to near and far reach positions resulted in the lowest RMS values. The mean RMS values without support stand for biceps muscles was the lowest in middle position (0.139 mv). Similarly, the mean RMS values of anterior deltoid (0.231 mv) and trapezius (0.066 mv) muscles without overhead support stand were least for the middle position. The mean RMS values for the bicep (0.105 mv), anterior deltoid (0.155 mv) and trapezius (0.041 mv) muscles with overhead support stand were the lowest during the middle position. The subjective rating results also supported the above conclusions. Show more

Keywords: Overhead work, muscular load, tool support, EMG, working position

DOI: 10.3233/OER-2010-0177

Citation: Occupational Ergonomics, vol. 9, no. 1, pp. 1-11, 2010

Authors: Muzammil, M. | Singh, Ranvir | Ahmad, Saman | Hasan, Faisal

Article Type: Research Article

Abstract: It has been shown that vibration level, push force, exposure duration and working posture cause unfavorable effects on the work performance when hand held vibrating tools are used by operators. The present study analyzed the effects of these variables on the heart rate and systolic blood pressure of the operators carrying out a manual-grinding task. Four levels of vibration (12.5, 13.6, 14.8 and 18 m/s2 ), three levels of push force (5, 10, 15 N), three levels of working posture (180°, 150° and 120° elbow flexion) and three exposure durations of 3, 5 and 7 min were selected for the …study. Thirty male subjects with no prior experience in the field of grinding participated in the study. Results indicated that in the kind of task undertaken, the main effect of equivalent level of vibration, exposure duration, push force and working posture were all statistically significant. Also an increase in the change in blood pressure and heart rate values were observed with the increase in exposure duration and push force. When the task was performed with flexion angle of 120°, change in heart rate and blood pressure values was minimum when compared with the other two working postures. Relevance to industry: Workers using various hand held tools are prone to injuries. Present research may help greatly in reducing task related injuries and enhance performance. Show more

Keywords: Manual grinding task, vibration level, push force, exposure duration, blood pressure, heart rate

DOI: 10.3233/OER-2010-0178

Citation: Occupational Ergonomics, vol. 9, no. 1, pp. 13-26, 2010

Authors: Hoffmann, Georg | Griesmacher, Andrea | Bartenbach, Christian | Schobersberger, Wolfgang

Article Type: Research Article

Abstract: High-quality workplace illumination exerts a number of benefits with respect to the employees' productivity as well as the maintenance of a physiological circadian rhythm and well-being. In the present study, two different lighting environments were investigated, one representing a standard lighting design in a window-less office (500 lux, 4000 K), the other providing a variable setup (500–1800 lux, 6500 K). The variable lighting system resulted in the expected effects on parameters of circadian rhythm (e.g. a decreased serum melatonin concentration at the end of each day of the study). However, the test light with its variable intensities and higher color …temperature did not turn out to be superior to the regular workplace illumination. Show more

Keywords: Lighting, circadian rhythm, melatonin, office workplace, performance

DOI: 10.3233/OER-2010-0179

Citation: Occupational Ergonomics, vol. 9, no. 1, pp. 27-39, 2010

Authors: Callaghan, Jack P. | Coke, Stephanie K. | Beach, Tyson A.C.

Article Type: Research Article

Abstract: The objective of this study was to conduct gender- and time-based comparisons of postural and discomfort responses during prolonged simulated driving. Prolonged driving has been linked with low back disorders (LBD), however underlying mechanisms of pain or injury are not well understood despite many efforts to delineate the biomechanics of automobile seating. Twelve males and 12 females were exposed to one hour of simulated automobile driving. Body postures, body-seat pressure distributions, and ratings of perceived discomfort were documented and gender- and time-based comparisons were performed. Females exhibited approximately 10° greater changes in lumbo-pelvic orientation when upright standing postures were compared …to those in automobile seating. Attributed to gender-based differences in body size was the finding that males experienced significantly greater body-seat interface pressures. Many of the postural, pressure, and discomfort measures varied significantly over 30 to 45 minutes, and these variations were mostly consistent between genders. Many variables examined varied as a function of gender and duration of driving. Future biomechanical investigations of automobile seating design for more effective LBD prevention should consider these potential effects in order to gain further insight into potential low back pain- or injury-generating mechanisms. Show more

Keywords: Gender differences, lumbar spine flexion, pelvis, interface pressure distribution, automobile seat, sitting

DOI: 10.3233/OER-2010-0180

Citation: Occupational Ergonomics, vol. 9, no. 1, pp. 41-53, 2010

Authors: McGill, Stuart | Belore, Melanie | Crosby, Ian | Russell, Caryl

Article Type: Research Article

Abstract: Given that torso muscle endurance is one of the few metrics that has been shown to be linked to having a history of back disorders together with predicting future back disorders, endurance tests for workers have been developed. While some data exists on the V-sit exercise for flexor endurance, some have specifically adopted the plank test. The primary objective of this study was to assess links between the two tests. Two data sets were collected. The first set was obtained from a convenience group of fire fighters where the plank endurance test scores, together with the Biering Sorensen test for …extension endurance, were obtained over three years. The second data set was obtained from a tightly controlled cross-sectional study of university students that included scores for both flexor and extensor endurance. 620 fire fighters for the first data set and 181 university students for the second. While flexor endurance in the firefighters peaked when aged in their 40's, extensor endurance peaked in their 20's. In the study of university students, the plank scores were relatively higher than the V-sit scores in males but relatively lower than the V-sit in the females. A pearson correlation test between the paired plank and V-sit scores of each subject rendered a coefficient of r =0.34. This means that the performance on one flexor test only predicted 11% of the score in the other. ANOVA comparison of scores based on their history of having had shoulder or back troubles showed no significant link between V-sit or plank scores. The plank scores are not well correlated with the V-sit scores suggesting that the two measure different variables. Since more data exists for the V-sit, measurement of flexor endurance in occupational settings using this test probably forms a stronger link to back injury. Show more

Keywords: Endurance, back pain, muscle testing

DOI: 10.3233/OER-2010-0181

Citation: Occupational Ergonomics, vol. 9, no. 1, pp. 55-61, 2010

Article Type: Correction

DOI: 10.3233/OER-2010-9106

Citation: Occupational Ergonomics, vol. 9, no. 1, pp. 63-63, 2010