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- Dahlqvist, Camilla, et al.
(författare)
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Comparing two methods to record maximal voluntary contractions and different electrode positions in recordings of forearm extensor muscle activity : refining risk assessments for work-related wrist disorders
- 2018
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Ingår i: Work. - : IOS Press. - 1051-9815. ; 59:2, s. 231-242
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Tidskriftsartikel (refereegranskat)abstract
- Background: Wrist disorders are common in force demanding industrial repetitive work. Visual assessment of force demands have a low reliability, instead surface electromyography (EMG) may be used as part of a risk assessment for work-related wrist disorders. For normalization of EMG recordings, a power grip (hand grip) is often used as maximal voluntary contraction (MVC) of the forearm extensor muscles. However, the test-retest reproducibility is poor and EMG amplitudes exceeding 100% have occasionally been recorded during work. An alternative MVC is resisted wrist extension, which may be more reliable.Objective: To compare hand grip and resisted wrist extension MVCs, in terms of amplitude and reproducibility, and to examine the effect of electrode positioning.Methods: Twelve subjects participated. EMG from right forearm extensors, from four electrode pairs, was recorded during MVCs, on three separate occasions.Results: The group mean EMG amplitudes for resisted wrist extension were 1.2-1.7 times greater than those for hand grip. Resisted wrist extension showed better reproducibility than hand grip.Conclusions: The results indicate that the use of resisted wrist extension is a more accurate measurement of maximal effort of wrist extensor contractions than using hand grip and should increase the precision in EMG recordings from forearm extensor muscles, which in turn will increase the quality of risk assessments that are based on these.
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| 5. |
- Dahlqvist, Camilla, et al.
(författare)
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Self-recordings of upper arm elevation during cleaning - comparison between analyses using a simplified reference posture and a standard reference posture
- 2018
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Ingår i: BMC Musculoskeletal Disorders. - : BMC. - 1471-2474. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Background To reduce ergonomic risk factors in terms of awkward and constrained postures and high velocities, it is important to perform adequate risk assessments. Technical methods provide objective measures of physical workload. These methods have so far mainly been used by researchers. However, if written instructions how to apply the sensors and how to adopt the reference posture are provided, together with triaxial accelerometers, it may be possible for employees to record their own physical workload. The exposure in terms of e.g. upper arm elevations could then easily be assessed for all workers in a workplace. The main aims of this study were: 1) to compare analyses for self-recording of upper arm elevation during work using a simplified reference posture versus using a standard reference posture, and 2) to compare the two reference postures.MethodsTwenty-eight cleaners attached an accelerometer to their dominant upper arm and adopted a simplified reference according to a written instruction. They were thereafter instructed by a researcher to adopt a standard reference. Upper arm elevations were recorded for 2 or 3 days. Each recording was analysed twice; relative to the simplified reference posture and relative to the standard reference posture. The group means of the differences in recorded upper arm elevations between simplified and standard reference analyses were assessed using Wilcoxon signed ranks test. Furthermore, we calculated the group mean of the differences between the simplified reference posture and the standard reference posture.ResultsFor arm elevation during work (50(th) percentile), the group mean of the differences between the two analyses was 0.2 degrees (range-7 - 10 degrees). The group mean of the differences between the two references was 9 degrees (range 1-21 degrees). The subjects were able to follow the instructions in the protocol and performed self-recording of upper arm elevation and velocity.ConclusionsThe small difference between the two analyses indicates that recordings performed by employees themselves are comparable, on a group level, with those performed by researchers. Self-recordings in combination with action levels would provide employers with a method for risk assessment as a solid basis for prevention of work-related musculoskeletal disorders.
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| 6. |
- Dahlqvist, Camilla, et al.
(författare)
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Validity of a small low-cost triaxial accelerometer with integrated logger for uncomplicated measurements of postures and movements of head, upper back and upper arms
- 2016
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Ingår i: Applied Ergonomics. - : Elsevier. - 0003-6870 .- 1872-9126. ; 55, s. 108-116
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Tidskriftsartikel (refereegranskat)abstract
- Repetitive work and work in constrained postures are risk factors for developing musculoskeletal disorders. Low-cost, user-friendly technical methods to quantify these risks are needed. The aims were to validate inclination angles and velocities of one model of the new generation of accelerometers with integrated data loggers against a previously validated one, and to compare meaurements when using a plain reference posture with that of a standardized one. All mean (n = 12 subjects) angular RMS-differences in 4 work tasks and 4 body parts were <2.5° and all mean median angular velocity differences <5.0 °/s. The mean correlation between the inclination signal-pairs was 0.996. This model of the new generation of triaxial accelerometers proved to be comparable to the validated accelerometer using a data logger. This makes it well-suited, for both researchers and practitioners, to measure postures and movements during work. Further work is needed for validation of the plain reference posture for upper arms.
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| 7. |
- Hemphälä, Hillevi, et al.
(författare)
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Visual ergonomics interventions in mail sorting facilities
- 2012
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Ingår i: Work. - 1051-9815 .- 1875-9270. ; 41:1, s. 3433-3437
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Tidskriftsartikel (refereegranskat)abstract
- This study was performed between 2004 and 2011 at mail sorting facilities in Sweden. During this time, different interventions were performed. The first was a lighting intervention that had a positive impact on the postal workers, especially those with eyestrain. A new lighting system also improved the illuminance and gave better light distribution. The second intervention involved new personal spectacles for the postal workers who needed them and this had a positive effect on eyestrain. The third intervention involved a specific type of sorting spectacles for the postal workers who already used progressive lenses privately. The reading distances that the postal workers had while sorting the mail was inverted to the distances in their regular progressive lenses. The new sorting spectacles had a positive effect on head postures and on muscular activity.
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| 8. |
- Hemphälä, Hillevi, et al.
(författare)
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Working spectacles for sorting mail
- 2014
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Ingår i: Work. - 1051-9815 .- 1875-9270. ; 47:3, s. 319-327
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Sorting mail into racks for postmen is visually demanding work. This can result in backward inclination of their heads, especially more pronounced for those who use progressive addition lenses. OBJECTIVE: To evaluate the effects of customized working spectacles on the physical workload of postmen. METHODS: Twelve male postmen sorted mail on two occasions: once using their private progressive spectacles and once using customized sorting spectacles with inverted progressive lenses. Postures and movements of the head, upper back, neck, and upper arms were measured by inclinometry. The muscular load of the trapezius was measured by surface electromyography. RESULTS: With the customized sorting spectacles, both the backward inclination of the head and backward flexion of the neck were reduced (3 degrees), as well as the muscular load of the right upper trapezius, compared to sorting with private spectacles. However, with the sorting spectacles, there was a tendency for increased neck forward flexion, and increased sorting time. CONCLUSION: The reduction in work load may reduce the risk for developing work-related musculoskeletal disorders due to the positive reduction of the backward inclination of the head. But the tendency for increased neck forward flexion may reduce the positive effects. However, the magnitude of the possible reduction is difficult to predict, especially since quantitative data on exposure-response relationships are unknown. Alternative working spectacles with inverted near progressive lenses ought to be evaluated. They should still result in a positive reduced backward inclination of the head and may not cause any increased forward flexion.
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| 9. |
- Vencel Jacobsson, Maria, et al.
(författare)
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Bör kunder vända streckkoden rätt i kassan?
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- EAN-kodens betydelse vid scanning av varorAtt arbeta som kassör vid utgångskassa anses vara ergonomiskt belastande. En vanlig uppfattning är att om kunden lägger varorna en och en på bandet samt vänder EAN-koden mot scannern, så minskar kassörens arbetsbelastning.Arbets- och miljömedicin Syd har i samarbete med Handelsanställdas Förbund genomfört en pilotstudie i kassaarbete vid scanning av varor. Pilotstudiens syfte är att undersöka om det finns någon skillnad i kassörens fysiska belastning om kunden vänder EAN-koden rättvänd på bandet i utgångskassa, jämfört med om varorna läggs med EAN-koden icke-rättvänd. Vi genomförde tekniska mätningar på en erfaren kassör, där arbetsställningar, arbetsrörelser och muskelaktivitet registrerades i båda situationerna. Resultaten visade mycket tydliga skillnader i belastning. Arbete med rättvänd EAN–kod innebar betydligt lägre rörelsehastigheter i överarm och handled, lägre muskelbelastning i skuldra och underarm, samt mer tid för muskulär återhämtning i skuldrans muskulatur, jämfört med icke-rättvänd kod. Möjlighet till muskulär återhämning i underarmens muskler var extremt låg i båda situationerna. Det tog i genomsnitt längre tid att skanna varorna med rättvänd kod, men tiden varierade mycket mellan olika kunder. Efter justering för tiden kvarstod de statistiskt signifikanta skillnaderna i belastning.Sammanfattningsvis visade undersökningen att det fanns stora ergonomiska fördelar för kassören om kunden lägger varan med rättvänd EAN-kod vid scanning av varor.
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| 10. |
- Vencel Jacobsson, Maria, et al.
(författare)
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Har EAN-kodens placering någon betydelse för arbetsbelastningen vid kassaarbete? : Rapport nr 2
- 2018
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Rapport (populärvet., debatt m.m.)abstract
- Att arbeta som kassör vid utgångskassa anses vara ergonomiskt belastande. En vanlig uppfattning är att om kunden lägger varorna en och en på bandet samt vänder EAN-koden mot scannern, så minskar kassörens arbetsbelastning.Arbets- och miljömedicin Syd har i samarbete med Handelsanställdas Förbund genomfört en pilotstudie i kassaarbete vid scanning av varor. Pilotstudiens syfte är att undersöka om det finns någon skillnad i kassörens fysiska belastning om kunden vänder EAN-koden rättvänd på bandet i utgångskassa, jämfört med om varorna läggs med EAN-koden icke-rättvänd.Vi genomförde tekniska mätningar på en erfaren kassör, där arbetsställningar, arbetsrörelser och muskelaktivitet registrerades i båda situationerna.Resultaten visade mycket tydliga skillnader i belastning. Arbete med rättvänd EAN–kod innebar betydligt lägre rörelsehastigheter i överarm och handled, lägre muskelbelastning i skuldra och underarm, samt mer tid för muskulär återhämtning i skuldrans muskulatur, jämfört med icke-rättvänd kod. Möjlighet till muskulär återhämning i underarmen muskler var extremt låg i båda situationerna.Det tog i genomsnitt längre tid att skanna varorna med rättvänd kod, men tiden varierade mycket mellan olika kunder. Efter justering för tiden kvarstod de statistiskt signifikanta skillnaderna i belastning.Sammanfattningsvis visade undersökningen att det fanns stora ergonomiska fördelar för kassören om kunden lägger varan med rättvänd EAN-kod vid scanning av varor.
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