Kombinationsexpositionen von Ganzkörper-Vibrationen und Körperhaltungen
- Combined exposures of whole-body vibration and posture
Raffler, Nastaran; Ochsmann, Elke Birgit (Thesis advisor); Dißelhorst-Klug, Catherine (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2017, Kumulative Dissertation
Low back pain and local pain at the cervical spine are the most reported injuries of occupational drivers. Medical treatment and sick leaves are the costly consequences. One of the most important physical factors of musculoskeletal complaints is awkward posture, besides whole-body vibration (WBV) exposures. Due to the complexity of field measurement of posture, these exposures have been assessed so far mostly by self-evaluation and questionnaires.This works continues the work of a study which showed the feasibility of the measuring system CUELA (Computer-assisted registration and long-term analysis of musculoskeletal workloads) for the measurement of the combined exposures of posture and WBV. To develop this measuring system further, this work (1) used CUELA for the first time at representative work places and proposed an assessment scheme which is relevant for practical use (2) compared the self-evaluation of the exposure with field measurements .(1) The combined exposures of posture and WBV have been measured for the first time for occupational drivers during several different, routine operations (tram, helicopter, saloon car, van, forklift, two mobile excavators, wheel loader, tractor, elevating platform truck). As a result, the posture exposure is largest for the wheel-loader and tractor operators, while the helicopter pilot and the van driver have experienced the lowest posture exposures. However, the combined exposures are largest for the operators of the tractor and the elevating platform truck. The combined exposures of posture and WBV are thus related for the first time quantitatively to the operations and vehicles of this study. This is a basis for future assessments and studies (e.g., the design of case-control-studies).In addition, a new scheme for the quantitative assessment for the combined exposures of posture and WBV has been proposed. The measurement results have been assessed so far for individual body angles by means of literature and standard data and combined with WBV results. With the new scheme it is possible to assess the combined exposures in a single quantity which is a relevant advantage for practical applications. (2) The following study investigates the comparability and limits of self-evaluation with regard to field measurement for combined exposures. On the one hand the relation between questionnaire and field measurement data are investigated, on the other hand factors are identified that may influence the individual perception of WBV.To this end the self-evaluations of 45 occupational drivers concerning the combined exposures of posture and WBV have been compared to field measurements. Musculoskeletal complaints have been included into the investigation as additional factor. Although the measured WBV exposures have been small and very similar for all drivers, some of the drivers overestimated their WBV exposure ("WBV-over-estimators"). These drivers have significantly increased posture exposures for the head and back inclination as compared to those drivers that have not overestimated their WBV exposure. The "WBV-over-estimators" also have significantly increased musculoskeletal complaints in the areas of the thoracic and cervical spine as well as the shoulders and arms. Thus it has been shown that the self-evaluation of the WBV exposure can be influenced significantly by factors such as posture or musculoskeletal complaints which underlines the importance of field measurements and which should always be considered in further investigations.This work applied a measuring system of the combined exposures of posture and WBV for the first time at work places during normal operations. In addition, it developed a new scheme for the quantitative analysis of the measurement results. Finally, the influences on the self-evaluation of WBV exposures have been investigated which underlined the importance of field measurements for further investigations as compared to the use of questionnaires.