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- Rose, Linda M., et al.
(författare)
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Fatigue and recovery during and after static loading
- 2014
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Ingår i: Ergonomics. - : Informa UK Limited. - 0014-0139 .- 1366-5847. ; 57:11, s. 1696-1710
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Tidskriftsartikel (refereegranskat)abstract
- Subjectively assessed endurance time (ET), resumption time (RT) and perceived discomfort, pain or fatigue (PD), and objectively measured maximum force-exerting capacity were investigated for varying loads and durations of a pushing task with two repeated trials. Beyond the main results quantifying how the load scenario affected ET, RT and PD, three additional results are of note: (1) although the maximum pushing force did not change between trials, shorter ET, longer RT and higher PD indicated accumulation of fatigue in Trial 2; (2) the PD ratings showed a trend with a linear increase during loading and a curvilinear decrease during recovery; and (3) the RT and the load level for different relative loading times were found to have an unexpected U-shaped relationship, indicating lowest fatigue at the intermediate load level. These results can be used to model a more sustainable and productive work-recovery ratio.
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| 2. |
- Hägg, Göran M, et al.
(författare)
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Knife force differences when cutting meat at different temperatures
- 2012
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Ingår i: NES2012. - Stockholm : KTH Royal Institute of Technology. - 9789163711497
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Konferensbidrag (refereegranskat)abstract
- IntroductionMeat cutters in abattoirs is a group with high risks for musculoskeletal disorders. A major reason for this is that they exert high hand forces over a great part of the day when cutting meat. Though meat is refrigerated due to hygienic demands, meat temperature can vary. Meat cutters have claimed that knife forces increase with lower temperatures. This study was performed to find out what effects the meat temperature has on cutting forces. In addition, the same issue was addressed for pure fat.MethodTo be able to do cuts in meat under controlled conditions while measuring cutting forces, a machine, Anago KST Sharpness Analyzer, was used. The machine normally runs a knife at constant speed through a standardized textile ribbon while the force exerted on the ribbon is recorded over time. For this investigation, the ribbon was replaced by a wooden fixture with a 10 mm wide slot where the knife could pass and where meat samples could be fixed.Meat obtained from hind loin and fat tissue of pork was cut into 5 cm long, 4 cm wide and 2 cm thick samples. The meat fibre orientation was aligned with the long axis of the sample. When fixated in the fixture and the machine was started, the knife made a 4 cm long cut through 2 cm thick meat or fat.One hundred and forty four samples of meat and as many of fat were collected and put overnight in one of three refrigerators with temperatures 2, 7 and 12 °C, 48 in each. Well sharpened standard knifes were used for the tests. The knife was changed after 24 cuts. During the procedure samples were taken directly from the refrigerator and put into the fixture and tested immediately. The sample order was generally 2, 7, 12 °C to avoid systematic effects of a gradually blunter knife.ResultsThere were no significant differences in knife forces at the three meat temperatures. The forces for fat were in average about three times higher than the meat forces. There was no significant difference between forces in fat at 7 and 12 °C. However there was a strongly significant difference between these two groups and the 2 °C fat group. The force was about 30% higher compared to the forces at 7 and 12 °C in fat.ConclusionIn the range 2-12 °C there are no differences in meat. For fat there are no differences in the range 7-12 °C while the force increases about 30% when going from 7 to 2 °C.
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