Combined and additive effects of assembly tasks and constrained body postures
- Authors: Skelton, Sarah Anne
- Date: 2007
- Subjects: Musculoskeletal system -- Diseases , Human engineering , Posture , Posture disorders , Work -- Physiological aspects , Occupational diseases , Manual work , Job stress
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5107 , http://hdl.handle.net/10962/d1005185 , Musculoskeletal system -- Diseases , Human engineering , Posture , Posture disorders , Work -- Physiological aspects , Occupational diseases , Manual work , Job stress
- Description: Despite extensive research into musculoskeletal disorders (MSDs) they continue to plague workers. Manual materials handling (MMH), in particular the concurrence of load manipulation and awkward body posture, has been identified as a key factor in the onset of MSDs. Only a few studies have looked at the interaction between manipulation tasks and working posture during assembly tasks and as a result their relationship has not been widely explored. Assessing the stresses resulting from individual task factors and body posture in isolation and adding them together may be too simplified to estimate an overall risk profile, since this does not take into account that there may be a non-linear interaction in strain responses when manipulation task and body posture interact. Therefore, the present study investigated biophysical, physiological and psychophysical responses to combined tasks, rather than individual tasks of body posture and manipulative tasks. The objective of the research was to establish the interactive effects of constrained body postures and manipulative tasks and to identify whether a cumulative or compensatory reaction occurs during this interaction. Nine conditions were assessed in a laboratory setting, which included combinations of three working postures (standing, sitting and stooping) and three assembly tasks (torque wrenching, precision and no task). Thirty-six subjects were required to complete all nine conditions, with each condition lasting ninety seconds. Muscle activity was recorded for seven muscles from the upper extremity, trunk and lower extremity regions and was complemented by physiological (heart rate, tidal volume, minute ventilation, oxygen consumption, energy expenditure and breathing frequency) and psychophysical (body discomfort) data. At the completion of all nine conditions subjects completed a retrospective psychophysical rating questionnaire pertaining to discomfort felt during the conditions. Responses obtained for the different task and posture combinations revealed compensatory reactions (additive > combined) for most of the conditions assessed for the biomechanical and physiological responses. In the majority of cases for muscle activity, no significant differences were found between the combined and the additive effects (p < 0.05), while for the physiological responses there were mostly significant differences observed. Psychophysical responses indicated that there was a significant difference overall between the additive and combined effects. The results of this study demonstrate that in order to identify risk areas, manipulation tasks and constrained working postures may be considered either in isolation and added together (additive) or as a combined task, since there were very few significant differences observed between these two effects. Further studies are required, however, to provide conclusive evidence.
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- Date Issued: 2007
Strategies for managing work related stress
- Authors: Müller, Elsie Franscina
- Date: 2007
- Subjects: Stress management , Job stress , Work -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8577 , http://hdl.handle.net/10948/742 , Stress management , Job stress , Work -- Psychological aspects
- Description: The objective of this study was to identify the strategies (primary, secondary and tertiary) that can be employed to manage work related stress. A questionnaire, was designed based on the strategies found in a literature study on the topic and used to gather inputs from academic head of department and lecturers. The questionnaire was delivered by hand to 18 potential respondents. All 16 questionnaires returned could be used. These were processed and analysed using Microsoft Excel spreadsheets. In general support was found for primary stress management strategies pertaining to work schedule, work load and work pace, job content, career development, the home-work relationship and work environment. Lifestyle management in terms of physical activities and a healthy diet were regarded as the preferred secondary stress management strategies. The strategies related to lifestyle management which were identified from the literature study were physical activities, healthy diet, relaxation techniques such as meditation and yoga. Support was found for tertiary stress management strategies but most of the respondents were not sure if their organisation offered any wellness, employee assistance or stress management programmes. Wellness programmes were indicated as a strategy that will have the most impact on reducing work related stress and employee assistance programmes (EAPs) ranked there after. Overall respondents indicated that they did not perceive their work as very stressful.
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- Date Issued: 2007