| 1. |
- Elcadi, Guilherme H.
(författare)
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Near infrared spectroscopy for assessing oxygenation and hemodynamics in the upper extremities of healthy subjects and patients with work-related muscle pain
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The prevalence of work-related muscle pain (WRMP) is large in the general population in the industrialized world. Despite significant advances over recent years in some research areas, the mechanisms of why WRMP occurs and the pathophysiological mechanisms behind the disorders are still unclear. One suggested explanation is that WRMP is caused initially by a limitation of the local muscle circulation and oxidative metabolism. There is a lack of objective methods to gauge the development and diagnosis of WRMP. Near infrared spectroscopy (NIRS) is a non-invasive technique that allows for determinations of oxygenation and blood flow. The purpose of this thesis was to evaluate NIRS (1) as a method for measuring muscle oxygenation and hemodynamics for the extensor carpi radialis (ECR) and trapezius descendens muscles (TD), and (2) to investigate whether variables measured by NIRS differed between patients diagnosed with WRMP and healthy subjects. Several variables of NIRS were produced and investigated. These included muscle oxygenation (StO2%), changes during contractions (∆StO2%) and StO2% recovery (Rslope), total hemoglobin (HbT) as an indication of blood volume and its changes during contractions (∆HbT). In addition, for the ECR, by applying an upper arm venous occlusion (VO) HbTslope increase as a surrogate of blood flow, and for both VO and arterial occlusion (AO) HHbslope increase (i.e. deoxyhemoglobin slope) as a surrogate of oxygen consumption were variables of interest. A first objective was to determine how StO2% and HbT responded to various contraction forces and how it related to muscle activation measured by electromyography (EMG). For both muscles isometric contractions of 10, 30, 50 and 70% of maximal voluntary contraction (MVC) were maintained for 20 s each by healthy males and females; additionally a 10% MVC contraction was sustained for 5 min. For the different contraction levels, predictable relationships were seen between ∆StO2% and force, and between ∆StO2% and EMG RMS amplitude. The general trend was a decrease in ∆StO2% with increasing force and increasing EMG. Females showed a tendency for a higher oxygen use (i.e., drop in StO2%) for the ECR over force levels than males and a higher RMS% MVC for the TD. For the 10% MVC contraction sustained for 5 min gender specific changes over time for HbT and RMS for the ECR, and for StO2% for the TD muscle were seen. A second objective was to determine the day-to-day reliability of NIRS variables for the ECR and TD muscles at group level (Pooled data) and at gender level (males and females). Measurements were performed on two occasions separated by 4-6 days and intraclass correlation coefficients (ICC) and limits of agreement (LOA) were determined as reliability and reproducibility indicators, respectively. Variables tested were ∆StO2% during submaximal isometric contractions of 10, 30, 50 and 70% MVC and StO2% recovery (Rslope) after contractions and after AO. For the ECR, HbTslope as an indication of blood flow (using VO) and HHbslope as a surrogate of oxygen consumption for both VO and AO were computed. For ∆StO2% for the ECR the highest ICC was at 30% MVC for both the pooled data and at gender level. For the TD ICCs were comparably high for 30, 50, 70 % MVC (for both muscles the ∆StO2% at 10% MVC showed the lowest ICC). Further, females showed a higher ICC than males for contraction levels of 50 and 70% MVC. For both muscles, LOA for ∆StO2% was lowest at 10% and highest at 50 and 70% MVC. For the ECR Rslope ICCs were high for all contraction levels, but was lower for AO; LOA was lowest at 70% MVC. For the TD, Rslope ICCs were also high for all contraction levels and LOA was lowest at 30 % MVC. ICC for HbTslope was the lowest of all variables tested. For HHbslope ICC was higher for AO than for VO, and LOA was lower for AO. A third objective was to determine if there were differences between healthy subjects and patients diagnosed with WRMP in ∆StO2% and ∆HbT responses during varying submaximal contractions (10, 30, 50 and 70% MVC), and StO2% recovery (Rslope) immediately after contractions and AO. Additional variables tested in the ECR at rest were HHbslope to indicate oxygen consumption (using AO) and HbTslope as an indication of blood flow. There were no differences between groups in ∆StO2% and ∆HbT variables during the contractions or Rslope in the recovery after contractions or AO. Furthermore, HbTslope was not different between groups However, oxygen consumption for the ECR and StO2% for the TD at rest were significantly greater for healthy subjects compared to patients. A fourth objective was to determine if there were differences in StO2% and HbT between healthy subjects and WRMP patients during a 12 min sustained contraction of 15 % MVC. In addition, the protocol included a recovery period of 30 min. Prior to contraction, as well as during the recovery period, HbTslope as a surrogate of blood flow was determined for the ECR. Neither the ECR nor the TD exhibited significant differences between groups for StO2% and HbT during the contraction. For the TD patients showed a lower StO2% value at rest and throughout the contraction than healthy subjects. For the ECR HbT during the sustained contraction the general trend was an initial decrease with gradual increase throughout the contraction for both groups. For HbTslope no differences were seen between patients and healthy subjects before the sustained contraction and during the recovery period for both muscles.NIRS is deemed a suitable technique for assessing physiological measurements of the upper extremity, including for day-to-day testing.NIRS was not able to distinguish between the patients with WRMP and controls. A concern in the thesis is the characteristics of the patient group in being equally active in recreational sports, actively working, and similar in muscle strength as controls. Thus, applying NIRS for studying a more severe patient group could yield different results.
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| 2. |
- Bernmark, Eva, et al.
(författare)
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Head movements during two computer work tasks assessed by accelerometry
- 2011
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Ingår i: Applied Ergonomics. - : Elsevier. - 0003-6870 .- 1872-9126. ; 42:2, s. 309-313
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Tidskriftsartikel (refereegranskat)abstract
- We investigated whether potential differences in head inclinations and accelerations for two highly similar computer work tasks could be detected using (1) a triaxial accelerometer and (2) a simulated uniaxial accelerometer.Ten subjects’ head movements were registered with a triaxial accelerometer system for two similar document-management tasks at their work place: a fully electronic document-management task and one also involving paper documents.In situations where head movements were small, a triaxial accelerometer was able to discriminate between the different degrees of static work of the neck in terms of range of head inclinations and accelerations. A difference in head acceleration was also found by using a simulated uniaxial accelerometer. Thus, in terms of head movement and for work similar to this office work, potential dynamic differences in observationally similar work tasks can be investigated by using a triaxial accelerometer. For acceleration alone, a uniaxial accelerometer can also be used.
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| 3. |
- Bernmark, Eva, et al.
(författare)
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Validity of heart-rate based measurements of oxygen consumption during work with light and moderate physical activity
- 2012
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Ingår i: Work. - : IOS Press. - 1051-9815. ; 4141 Suppl 1, s. 5475-5476
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Tidskriftsartikel (refereegranskat)abstract
- For ergonomic purposes it is useful to quantify the energy expenditure and the level of physical activity imposed on workers. Oxygen consumption (VO₂) is often used to calculate energy expenditure and can be used as an indication of physical activity. Twenty-five subjects participated in the study. Oxygen consumption (VO₂) in L O₂/min and heart-rate (HR) in beats per minute (bpm) were simultaneously measured during different work tasks at each individual's workplace. Ninety-one different work tasks with light or moderate physical activity were included (physical activity was classified by the VO₂ measurements). Estimated oxygen consumption (L O₂/min) was then calculated by using the HR measurements in bpm combined with individual HR-VO₂ equations established in a laboratory. Although heart-rate based estimations of individual oxygen consumption showed relatively low precision, heart-rate measurements in combination with individual exponential HR-VO₂ equations can be used to discriminate between work involving light physical activity and work involving moderate physical activity.
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| 4. |
- Elcadi, Guilherme H., 1966-, et al.
(författare)
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Shoulder and forearm oxygenation and myoelectric activity in patients with work related muscle pain and healthy subjects
- 2013
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Ingår i: European Journal of Applied Physiology. - New York : Springer. - 1439-6319 .- 1439-6327. ; 113:5, s. 1103-1115
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Tidskriftsartikel (refereegranskat)abstract
- We tested hypotheses of (i) reduced oxygen usage, oxygen recovery, blood flow and oxygen consumption; and (ii) increased muscle activity for patients diagnosed with work related muscle pain in comparison to healthy controls. Oxygenation was measured with near infrared spectroscopy (NIRS), and muscle activity with EMG for the extensor carpi radialis (ECR) and trapezius descendens (TD) muscles. Eighteen patients with diffuse neck-shoulder-arm pain and seventeen controls (matched in age and sex) were equipped with NIRS and EMG probes. After determining an individual’s maximum voluntary contraction (MVC) force, short term (20 sec) isometric contractions for the ECR and TD of 10%, 30%, 50% and 70% MVC generated ∆StO2% and StO2% recovery (Rslope) from NIRS, and RMS%max from EMG signals. In addition, upper arm venous (VO) and arterial (AO) occlusions generated slopes of total hemoglobin (HbTslope) and deoxyhemoglobin (HHbslope) for the resting ECR as surrogates of blood flow and oxygen consumption, respectively. Mixed Model analyses, t-tests, and Mann-Whitney test were used to assess differences between groups. There was no significant difference in MVC between groups for either muscle. Also, ∆StO2%, Rslope for either muscle, and ECR-HbTslope were not different between groups, thus our hypotheses of reduced oxygen use, recovery, and blood flow for patients were not confirmed. However, patients had a significantly lower ECR-HHbslope confirming our hypothesis of reduced consumption. Further, there was no difference in RMS%max during contractions meaning that the hypothesis of increased activity for patients was not confirmed. When taking into account the number of NIRS variables studied, differences we found between our patient group and healthy controls (i.e. in forearm oxygen consumption and shoulder oxygen saturation level) may be considered modest. Overall our findings may have been impacted by the fact that our patients and controls were similar in muscle strength, which is in contrast to previous studies.
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| 5. |
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| 6. |
- Forsman, Mikael, Professor, et al.
(författare)
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Co-variation in time between near-far accommodation of the lens and trapezius muscle activity
- 2012
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Ingår i: Work. - Reading, MA, USA : Andover Medical Publishers. - 1051-9815 .- 1875-9270. ; 41:Suppl. 1, s. 3393-3397
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Tidskriftsartikel (refereegranskat)abstract
- Visual strain and discomfort may contribute to the generation of work-related musculoskeletal disorders among e.g. computer workers. A positive correlation on a group level between eye-lens accommodation and trapezius muscle activity has been reported. In this study we investigated the possibility of a direct, fast, connection between lens accommodation and trapezius muscles activity. The subjects focused alternately on Near and Far targets, with a mean switch time of 5 s, through four different lenses. The cross-correlation, R(tau) was computed, between the time signals of accommodation and electromyography (EMG) from 23 subjects. In the overall mean R(tau) of 736 curves, a small but significant correlation peak (0.019) with a delay (of the EMG signal) of about 0.3 s, revealed a small common component in the two signals. Among the lenses, the positive lens (3.5 D), showed the highest correlation peak (0.040). The correlation may be caused by a direct “hard-wired” connection between the ciliary and trapezius muscles. But it could also be caused indirectly by the subject’s need for a more stable head in a more demanding visual task. The latter is supported by the result that the correlation was the highest in the positive lens condition. The present correlation is however weak and it has probably a low practical importance.
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| 7. |
- Forsman, Mikael, Professor, et al.
(författare)
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Participative development of packages in the food industry–evaluation of ergonomics and productivity by objective measurements
- 2012
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Ingår i: Work. - : IOS Press. - 1051-9815 .- 1875-9270. ; 4141 Suppl 1, s. 1751-1755
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Tidskriftsartikel (refereegranskat)abstract
- Rationalizations generally have a negative effect on health and known risk factors for musculoskeletal disorders. These effects may be reduced by paying attention to modifiers as worker participation and a resonant management style. In this study a participatory approach was used in the food industry in order to improve ergonomics and productivity. The food industry shows a high prevalence of musculoskeletal disorders, and repetitive manual work occurs extensively. Prototypes of new packaging solutions were developed in three cases, and compared in a simulated production to the existing production system through direct measurements of working postures and muscle activity, ratings of physical load, and general productivity data. Measured and rated ergonomic exposures showed that workload was significantly lower for the prototypes, in all three cases. In two cases, the number of handling operations included in the packaging operations were greatly reduced with the prototype package, as were production costs. The impact on disorders of the obtained load reductions is difficult to assess, but we believe that in "critical" situations like this, even small improvements may have an effect. This study shows that workloads during manual handling of packages as well as production costs can be reduced by applying participative development of packages.
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| 8. |
- Jonsson, Per, et al.
(författare)
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Thumb joint movement and muscular activity during mobile phone texting : A methodological study
- 2011
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Ingår i: Journal of Electromyography and Kinesiology. - : Elsevier. - 1050-6411. ; 21:2, s. 363-370
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The extended intensive use of mobile phones and other devices for Information and Communication Technology (ICT) could expose the thumbs and fingers to operational stresses beyond their intended function which may generate pain and musculoskeletal disorders in the thumbs and the associated joints. Studies characterizing biomechanical exposures associated with mobile phone use are limited to date and the use of electrogoniometry and EMG was assessed for characterizing thumb-based activities.Scope: The purpose was to investigate whether there were associations between thumb-based exposures registered with relatively easy-to-use electrogoniometric methods and more complicated EMG methods. Our hypothesis was that some outcome measures from the simpler electrogoniometric methods are related/correlated to and may be used as surrogate measure for the more complicated EMG methods.Conclusions: Due to low associations and the complementary nature of exposures collected with electrogoniometry and EMG, the results indicated both measures are necessary for characterizing thumb exposure during mobile phone text messaging. Only in a few, selected abduction/adduction activities, could electrogoniometry be used in lieu of EMG for assessing thumb exposures.
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| 9. |
- Lodin, Camilla, 1970-, et al.
(författare)
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Eye- and neck/shoulder-discomfort during visually demanding experimental near work
- 2012
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Ingår i: Work. - : IOS Press. - 1051-9815 .- 1875-9270. ; 41:Suppl. 1, s. 3388-3392
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Tidskriftsartikel (refereegranskat)abstract
- Frequent use of digital information technology has an impact on eye- and neck/shoulder-discomfort. Studies with cross sectional and intervention design indicate an association between the two symptom categories. Still, whether visually demanding near work, per se, contributes to increased neck/shoulder discomfort remains a question of debate. The aim of this laboratory study was to assess if visually demanding experimental near work affects eye- and neck/shoulder-discomfort when the posture was adjusted for comfort and no movements were allowed. Thirty-three healthy subjects performed a visually demanding computer screen task (viewing task) under four different optical lens conditions: binocular -3.5 D and monocular -3.5 D, +3.5 D and ±0 D. During the experiment subjects were seated in an office chair (with neck support) that was individually adjusted for comfort. At baseline and after each viewing task, subjects reported their perceived eye- and neck/shoulderdiscomfort on Borg’s CR-10 scale. Results show a significant increase of eye discomfort between baseline and the first viewing task, and a significant increase in neck/shoulder discomfort from baseline throughout the first three viewing tasks. Further analysis is required to determent whether the neck/shoulder discomfort was induced by the demanding near work or the static posture, or a combination.
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| 10. |
- Long, Jennifer, et al.
(författare)
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A definition of visual ergonomics
- 2014
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 45:4, s. 1263-1264
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 11. |
- Lunde, Lars-Kristian, et al.
(författare)
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Musculoskeletal health and work ability in physically demanding occupations : study protocol for a prospective field study on construction and health care workers
- 2014
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Musculoskeletal disorders have a profound impact on individual health, sickness absence and early retirement, particularly in physically demanding occupations. Demographics are changing in the developed countries, towards increasing proportions of senior workers. These senior workers may have particular difficulties coping with physically demanding occupations while maintaining good health. Previous studies investigating the relationship between physical work demands and musculoskeletal disorders are mainly based on self-reported exposures and lack a prospective design. The aim of this paper is to describe the background and methods and discuss challenges for a field study examining physical demands in construction and health care work and their prospective associations with musculoskeletal disorders, work ability and sickness absence.Methods and design: This protocol describes a prospective cohort study on 1200 construction and health care workers. Participants will answer a baseline questionnaire concerning musculoskeletal complaints, general health, psychosocial and organizational factors at work, work demands, work ability and physical activity during leisure. A shorter questionnaire will be answered every 6 months for a total of two years, together with continuous sickness absence monitoring during this period. Analysis will prospectively consider associations between self-reported physical demands and musculoskeletal disorders, work ability and sickness absence. To obtain objective data on physical exposures, technical measurements will be collected from two subgroups of N = 300 (Group A) and N = 160 (Group B) during work and leisure. Both group A and B will be given a physical health examination, be tested for physical capacity and physical activity will be measured for four days. Additionally, muscle activity, ground reaction force, body positions and physical activity will be examined during one workday for Group B. Analysis of associations between objectively measured exposure data and the outcomes described above will be done separately for these subpopulations.Discussion: The field study will at baseline produce objectively measured data on physical demands in the construction and health care occupations. In combination with clinical measurements and questionnaire data during follow-up, this will provide a solid foundation to prospectively investigate relationships between physical demands at work and development of musculoskeletal disorders, work ability and sickness absence.
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| 12. |
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| 13. |
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| 14. |
- PALM, Peter, et al.
(författare)
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Body worn video cameras with simultaneous technical measurements for ergonomic assessment of full work days
- 2014
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Ingår i: HUMAN FACTORS IN ORGANIZATIONAL DESIGN AND MANAGEMENT – XI NORDIC ERGONOMICS SOCIETY ANNUAL CONFERENCE – 46 A survey of methods for product design and development with regards to Ergoecological principlesA survey of methods for product design and development with regards to Ergoecological principlesER -.
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Konferensbidrag (refereegranskat)abstract
- Video is a powerful tool in ergonomic observations. However it is often time consuming to record a video and to identify demanding work postures. A time-saving method was developed: information from direct measurements synchronized with video of a body worn video camera was utilized to identify reasons for demanding work moments. This method was successfully tested on a 5.5-hour work shift of a garbage collector: 17 of 18 events when the worker bended forward were quickly identified in a video editing software with guidance of inclination data (inserted as an audio track) from an accelerometer attached to the worker’s back.
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| 15. |
- Reiman, Arto, et al.
(författare)
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Participatory video-assisted evaluation of truck drivers€™ work outside cab : deliveries in two types of transport
- 2014
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Ingår i: International Journal of Occupational Safety and Ergonomics. - : Taylor & Francis. - 1080-3548 .- 2376-9130. ; 20:3, s. 477-489
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify risks and ergonomics discomfort during work of local and short haul delivery truck drivers outside a cab. The study used a video- and computer-based method (VIDAR). VIDAR is a participatory method identifying demanding work situations and their potential risks. The drivers' work was videoed and analysed by subjects and ergonomists. Delivery truck drivers should not be perceived as one group with equal risks because there were significant differences between the 2 types of transportation and specific types of risks. VIDAR produces visual material for risk management processes. VIDAR as a participatory approach stimulates active discussion about work-related risks and discomfort, and about possibilities for improvement. VIDAR may be also applied to work which comprises different working environments.
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| 16. |
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| 17. |
- Richter, Hans O., et al.
(författare)
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Eye-lens accommodation load and static trapezius muscle activity
- 2011
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 111:1, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this experimental study was to investigate if sustained periods of oculomotor load impacts on neck/scapular area muscle activity. The static trapezius muscle activity was assessed from bipolar surface electromyography, normalized to a submaximal contraction. Twenty-eight subjects with a mean age of 29 (range 19–42, SD 8) viewed a high-contrast fixation target for two 5-min periods through: (1) -3.5 dioptre (D) lenses; and (2) 0 D lenses. The target was placed 5 D away from the individual’s near point of accommodation. Each subject’s ability to compensate for the added blur was extracted via infrared photorefraction measurements. Subjects whose accommodative response was higher in the -D blur condition (1) showed relatively more static bilateral trapezius muscle activity level. During no blur (2) there were no signs of relationships. The results indicate that sustained eye-lens accommodation at near, during ergonomically unfavourable viewing conditions, could possibly represent a risk factor for trapezius muscle myalgia.
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| 18. |
- Richter, Hans O., et al.
(författare)
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Stabilization of gaze : A relationship between ciliary muscle contraction and trapezius muscle activity
- 2010
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Ingår i: Vision Research. - : Elsevier BV. - 0042-6989 .- 1878-5646. ; 50:23, s. 2559-2569
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Tidskriftsartikel (refereegranskat)abstract
- In an experimental study four levels of oculomotor load were induced binocularly. Trapezius muscle activity was measured with bipolar surface electromyography and normalized to a submaximal contraction. Twenty-eight subjects with a mean age of 29 (range 19–42, std 8) viewed a high-contrast fixationt arget for four 5-min periods through: (i) 3.5 dioptre (D) lenses; (ii) 0 D lenses; (iii) individuallya djusted prism D lenses (1–2 D base out); and (iv) +3.5 D lenses. The target was placed close to thei ndividual’s age-appropriate near point of accommodation in conditions (i–iii) and at 3 m in condition( iv). Each subject’s ability to compensate for the added blur was extracted via infrared photorefraction measurements. A bitwise linear regression model was fitted on group level with eye-lens refraction on the x-axis and normalized trapezius muscle EMG (%RVE) on the y -axis. The model had a constant level of trapezius muscle activity – where subjects had not compensated for the incurred defocus by a change in eye-lens accommodation – and a slope, where the subjects had compensated. The slope coefficient was significantly positive in the D (i) and the +D blur conditions (iv). During no blur (ii) and prism blur (iii) there were no signs of relationships. Nor was there any sign of relationship between the convergence response and trapezius muscle EMG in any of the experimental conditions. The results appear directly attributable to an engagement of the eye-lens accommodative system and most likely reflect sensorimotor processing along its reflex arc for the purpose of achieving stabilization of gaze
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| 19. |
- Richter, Hans, 1961-, et al.
(författare)
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Temporal aspects of increases in eye-neck activation levels during visually deficient near work
- 2012
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Ingår i: Work. - : IOS Press. - 1051-9815 .- 1875-9270. ; 41:Suppl. 1, s. 3379-3384
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Tidskriftsartikel (refereegranskat)abstract
- In an experimental study two levels of oculomotor load were induced via optical trial lenses. Trapezius muscle activity was measured with bipolar surface electromyography and normalized to a submaximal contraction. Sixty-six subjects with a median age of 36 (range 19–47, std 8) viewed a black and white Gabor grating (5 c/deg) for two 7-min periods monocularly through a 0 D lens or binocularly through -3.5 D lenses. The effect of time was separately regressed to EMG in two different subgroups of responders: a High-Oculomotor-Load (HOL) and a Low-Oculomotor-Load (LOL) group. A linear regression model was fitted on group level with exposure time on the x-axis and normalized trapezius muscle EMG (%RVE) on the y-axis. The slope coefficient was significantly positive in the -D blur condition for only the HOL subgroup of responders: 0.926 + Time min 1-7x 0.088 (p = 0.002, r2 =0.865). There was no obvious sign of this activity to level off or to stabilize. These results suggest that professional information technology users that are exposed to a high level of oculomotor load, during extended times, are at an increased risk of exhibiting an increased trap.m. activity.
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| 20. |
- Takala, Esa-Pekka, et al.
(författare)
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Systematic evaluation of observational methods assessing biomechanical exposures at work
- 2010
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Ingår i: Scandinavian Journal of Work, Environment and Health. - : Finnish Institute of Occupational Health; National Research Centre for the  . - 0355-3140 .- 1795-990X. ; 36:1
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: This systematic review aimed to identify published observational methods assessing biomechanical exposures in occupational settings and evaluate them with reference to the needs of different users.Methods: We searched scientific databases and the internet for material from 1965 to September 2008. Methods were included if they were primarily based on the systematic observation of work, the observation target was the human body, and the method was clearly described in the literature. A systematic evaluation procedure was developed to assess concurrent and predictive validity, repeatability, and aspects related to utility. At least two evaluators independently carried out this evaluation.Results: We identified 30 eligible observational methods. Of these, 19 had been compared with some other method(s), varying from expert evaluation to data obtained from video recordings or through the use of technical instruments. Generally, the observations showed moderate-to-good agreement with the corresponding assessments made from video recordings; agreement was the best for large-scale body postures and work actions. Postures of wrist and hand as well as trunk rotation seemed to be more difficult to observe correctly. Intra- and inter-observer repeatability were reported for 7 and 17 methods, respectively, and were judged mostly to be moderate or good.Conclusions: With training, observers can reach consistent results on clearly visible body postures and work activities. Many observational tools exist, but none evaluated in this study appeared to be generally superior. When selecting a method, users should define their needs and assess how results will influence decision-making
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| 21. |
- Veiersted, Kaj Bo, et al.
(författare)
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Assessment of time patterns of activity and rest in full-shift recordings of trapezius muscle activity - Effects of the data processing procedure
- 2013
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Ingår i: Journal of Electromyography & Kinesiology. - : Elsevier BV. - 1873-5711 .- 1050-6411. ; 23:3, s. 540-547
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper was to compare the effects of different data reduction procedures on the values of variables characterizing the time pattern of trapezius muscle activity during full work shifts. Surface electromyography (EMG) of the right and left upper trapezius muscles were obtained from 40 young subjects in different occupations, mainly electricians, hairdressers and students. The target EMG variables were gap frequency, muscle rest, and the number and duration of episodes with sustained muscle activity (from 0.13 s to 30 min as minimum duration). These variables were derived from the EMG recordings using different Root Mean Square (RMS) windows (from 0.13 to 6.38 s), and discrimination levels between "activity" and "rest" (0.5%, 1% and 2% of maximal EMG). The results give basis for practical suggestions for EMG analyses of full work shifts. For most variables, a discrimination level of 0.5% EMG(max) showed to be preferable. The time proportion of muscle rest and sustained muscle activity should, in general, be preferred over the corresponding frequency measures. Sustained muscle activity should be calculated using a RMS window between 1 and 3 s, and preferably be stated in terms of variables describing time proportions of activity. Uninterrupted activity episodes longer than 10 min proved not to be a useful variable due to limited occurrence in many work shifts. (C) 2013 Elsevier Ltd. All rights reserved.
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| 22. |
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| 23. |
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| 24. |
- Wahlström, Jens, et al.
(författare)
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Upper arm postures and movements in female hairdressers across four full working days
- 2010
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Ingår i: Annals of Occupational Hygiene. - : Oxford University Press. - 0003-4878 .- 1475-3162. ; 54:5, s. 584-594
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To describe upper arm postures and movements among female hairdressers, including the variability between hairdressers, between days within hairdresser, and between tasks, as a basis for understanding the characteristics of exposures in the job, considering possible sources of variation and recovery, and discussing appropriate exposure assessment strategies.Methods: Data on upper arm postures were collected using inclinometers during four working days the same week from 28 female hairdressers working in 13 salons. Twenty of the hairdressers noted customer on and off times in a diary, to allow separate analyses of customer tasks (CT) and auxiliary non-customer tasks (AT), including breaks. For a number of posture and movement variables, mean values and variance components between subjects (BS) and within subjects between days (BD) were estimated using restricted maximum likelihood algorithms in one-way random effect models.Results: For the 20 hairdressers with diaries, CT accounted for 279 min (58%) (SDBS = 39 min and SDBD = 85 min) of the working day and AT and breaks for 207 min (42%) (SDBS = 46 min and SDBD = 88 min). The hairdressers worked with the right arm elevated >60° for 6.8% of the whole job (SDBS = 2.8% and SDBD = 2.0%). On average, the hairdressers worked with the right arm elevated >60° for 9.0% of the time during CT, compared to 3.7% during AT, resulting in a contrast between tasks of 0.35.Conclusions: Hairdressers may be at risk for developing musculoskeletal disorders in the neck and shoulders due to a considerable occurrence of highly elevated arms, especially during CT. On the other hand, we do not find reasons to classify hairdressing as a job with too little variation. Posture variability between days within hairdressers was in the same order of magnitude as that between hairdressers, suggesting that ‘typical’ workdays do not exist. The exposure contrast between CT and AT for variables describing elevated arm postures indicates that for these variables a simple task-based approach for estimating job exposure could be successful.
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