Does a weight support sling reduce lower back strain of sheep shearers?
Manual sheep shearing is still widely performed due to the quality and flexibility of task execution. However, the bent forward body posture, in combination with the clamping force required to hold the sheep, causes a very high workload, on particularly the for trunk, leg and lower back muscles. Although only moderate movements occur, awkward body posture and stabilization may cause average heart rates of more than 125 bpm. This type of task is performed throughout a whole day for many weeks during shearing season. In a field study it was tested, whether a weight support sling that carries part of the upper body weight, may help to reduce the back strain during sheep shearing. Surface electromyograms of six trunk, back and leg muscles, heart rate and shearing time were recorded. During three testing sessions (over a duration of six weeks) ten shearers were analyzed each shearing two sheep using the sling and shearing two sheep without a weight support sling. Habituation to the support sling was provided. On average the sling carried 86.74±(14.78)N. With respect of the body mass this is 10.3％ of the shearers body mass. It was found that the support sling may reduce muscular load of the musculus latissimus dorsi and the musculus biceps femoris significantly. No difference between shearing with and without weight support sling was observed for the shearing time, and heart rate. It is concluded that a weight support sling might (moderately) reduce back load of sheep shearers. Considering the high total workload for this job, the support sling is considered as one approach to contribute to a reduction of work strain.
Swantje ZSCHERNACK Matthias GOEBEL
Department of Human Kinetics and Ergonomics, Rhodes University, South Africa
国际会议
17th World Congress on Ergonomics(第十七届国际人类工效学大会)
北京
英文
1-6
2009-08-09（万方平台首次上网日期，不代表论文的发表时间）