Occupational Ergonomics - Volume 9, issue 3-4

Authors: Christie, Candice Jo-Anne

Article Type: Research Article

Abstract: The objective of this study was to assess the impact of a dietary and fluid intervention on workers doing heavy manual labour within the forestry industry. Fifty eight workers (29 Chainsaw Operators and 29 Stackers) were assessed in South Africa prior to, and during a 'normal' working shift. Body mass was measured and recorded prior to and on completion of the work shift. Heart rate responses were measured continuously during work and energy expenditure was predicted from the heart rate/oxygen uptake relationship obtained at a post-work progressive step up test completed by each worker. These data were then compared to …the initial study, previously published, in order to determine whether energy balance, fluid balance and workers' perceptions where altered by the provision of a dietary and fluid intervention programme. The data indicated that the relationship between energy expenditure and energy intake was substantially improved by the provision of food and fluid. Workers lost, on average, 1.94 kg body mass during work while felling and cross-cutting and 2.41 kg during stacking. This reduced significantly to a loss of 0.31 kg and 0.70 kg in the Chainsaw Operators and Stackers respectively following the introduction of water and food during the work period. Likewise, the energy deficit was significantly improved due to the introduction of a nutritional supplement. Pre-intervention the deficit was 8861.8 kJ (Chainsaw Operators) and 8804.2 kJ (Stackers) while in the post-intervention phase this deficit was reduced by approximately 50% for both groups of workers. Show more

Keywords: Chainsaw operators, stackers, energy intake, energy expenditure, dehydration

DOI: 10.3233/OER-2010-0184

Citation: Occupational Ergonomics, vol. 9, no. 3-4, pp. 119-126, 2010

Authors: Azar, Nadia R. | Godin, Christina A. | Andrews, David M. | Callaghan, Jack P.

Article Type: Research Article

Abstract: Cumulative low back loading has been shown to be a risk factor for low back pain reporting in the workplace. Evaluation of tasks outside of work might offer insight into why workers continue to have low back pain and may report pain differentially even when doing the same job. This study utilized a video-based 3D posture sampling approach to document joint postures of 18 people over a 2-hour period while performing non-repetitive tasks in and around their own homes. A 3D rigid link segment model was used to calculate reaction forces and moments at L4/L5 and joint models were used …to calculate joint forces. Average peak (4.0 kN) and cumulative (9.9 MN·s) compression force estimates indicate significant loads on the low back occur during non-occupational tasks, despite the fact that participants spent most of their time (86.2%) in neutral trunk postures. Cumulative anterior reaction shear force (440 kN·s) was found to be comparable to those documented for a wide variety of occupational tasks, when extrapolated to an 8-hour shift. To our knowledge, this study is the first to include a full complement of 3D low back forces and moments, in conjunction with an assessment of trunk posture, for non-occupational activities. The evidence suggests that considering 3D peak and cumulative low back loading during non-occupational tasks is warranted and may help to explain some of the variability in the reporting of workplace-related low back disorders despite extensive ergonomic intervention. Show more

Keywords: Cumulative load, non-occupational tasks, low back, 3D method, video, biomechanical model, non-work activities

DOI: 10.3233/OER-2010-0183

Citation: Occupational Ergonomics, vol. 9, no. 3-4, pp. 127-139, 2010

Authors: Perdeaux, Kevin M. | Fischer, Steven L. | Dickerson, Clark R.

Article Type: Research Article

Abstract: The extent to which specific muscles may limit maximum isometric force production is largely unknown. This study investigated shoulder muscle activity in six muscles and maximum force generation at the hand in three directions, while in eight different working positions. Ten right hand dominant, university-aged female participants completed twenty-four maximal isometric force hand exertions against a handle positioned by a robot arm within a 3-dimensional simulated workspace. A multivariate, full factorial ANOVA indicated a reach distance main effect where 11% greater force production occurred at the lesser reach distance. A target handle elevation and force direction interaction effect on maximum …force production also existed. These findings add to normative static strength data for hand locations typical of an operating work envelope. Although hand force was significantly influenced by position in each direction (p < 0.05), muscle EMG was not influenced in any of the six muscles measured. No muscle achieved 100% MVE in any of the tested conditions, with the highest total muscle activity recorded at 86% MVE for the Pectoralis Major – sternal origin. Collectively, these data better demonstrate that the location and direction of work presentation influences force outputs more than specific muscle demands (of those measured), and should be considered in evaluating workstations. Show more

Keywords: Maximal isometric force, muscle activity, shoulder strength, biomechanics

DOI: 10.3233/OER-2010-0185

Citation: Occupational Ergonomics, vol. 9, no. 3-4, pp. 141-151, 2010

Authors: Ugbolue, U. Chris | Nicol, Alexander C.

Article Type: Research Article

Abstract: The study assessed finger and wrist joint motion, temperature and volumetric measurements and reports a qualitative assessment resulting from repetitive industrial hand movements. Participants mimicked a series of industrial repetitive tasks incorporating the following hand movements: wrist flexion/extension task, repetitive grasp/release task; and pinch task. Each task was performed for a period of 5 minutes. Hand temperature and volumetric measurements were reported. Descriptive statistics and ANOVA were performed. Power analysis was performed to determine sample size (0.8) and significance was set at p=0.05. The results indicate that an increase in hand volume is accompanied by an increase in final temperature …of the hand. Of the three tasks mimicking an industrial repetitive activity, the repetitive grasp/release task produced the most range of motion (RoM), followed by the wrist flexion/extension task and then the pinch task. From the subjects' perception the wrist flexion/extension task was considered to be the most stressful task. Show more

Keywords: Work-related upper limb disorder, flexible electrogoniometric glove, industrial activity, hand volumetric measurement, hand temperature

DOI: 10.3233/OER-2010-0186

Citation: Occupational Ergonomics, vol. 9, no. 3-4, pp. 153-168, 2010

Authors: Slot, Tegan | Shackles, Emily | Dumas, Geneviève A.

Article Type: Research Article

Abstract: Tree planters use various strategies to unload the seedlings from their bags. This study examines differences in upper limb and trunk joint angles during three load carriage conditions: (1) load evenly distributed to the right and left sides of the body – evenly loaded (2) load entirely on the right side – right loaded and (3) load entirely on the left side – left loaded. Data were collected in the field in Northern Ontario. Inertial motion sensors were placed on the right hand, right and left forearms and upper arms, sacrum, and T1 vertebrae. Using relative sensor orientation, joint angles …were determined for the right wrist, right and left elbow and the trunk for the three load carriage conditions during normal planting tasks. The main findings were: 1) In the left loaded condition, the right wrist was less extended, the right elbow was more flexed, the trunk experienced less right-rotation, and the right and left forearms were less pronated than in either the evenly loaded or right loaded conditions. 2) In both the left and right loaded conditions, the left forearm was less pronated, and the trunk was less flexed than in the evenly loaded condition. Results suggest that asymmetrical tree load carriage results in more neutral postures than symmetrical tree load carriage. Show more

Keywords: Tree planting, upper limb, trunk, kinematics, musculoskeletal symptoms

DOI: 10.3233/OER-2010-0187

Citation: Occupational Ergonomics, vol. 9, no. 3-4, pp. 169-182, 2010