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Fig. 10 Repetitive work whcn throwtng the pieces into boxes. This task is probably one cause of the occurrence of epichondylites among butchers

(Fig. 11). Thus, when sawing he starts from a posilion of slight forward flexion and bends further forward, once for each cut. Also the risk of injuring himself on the saw leads to high psychological strain on the butcher.

Moving belts and conveyors are used for transportation. Only in large companies are ihey driven by motors and used for al! transportation. Therefore most handiing of matenals is manuał, causing high loads on shoulders and backs. Boxes weighing about 40 kg and mcat parts weighing 20-30 kg, even as much as 70 kg, are lifted and carried frequently (Fig. 12). Container* on wheels are used for bulk transportation of meat. The containers weigh up to and above 100 kg whcn filled and reąuire high forces to manoeuvre,especial!yonnarrow bends.'Another strenuous task is to push carcasses wluch are hanging on hooks on conveyors, especially as the floor is often very slippery.

Discussion

Butchers havc, without doubt, a hard job. Both the frequency of disordcrs and the butchers* experience of high loads signify this. Also the faci that only men are butchers and that they seldom remain butchers untU their pcnsionablc age supports this statemem. Disorders appear in all parts of the body. but the frequency of discomfort and pain was highest in the arms, shoulders and the Iow back. The troubles had led to sick leave for morę than half of the butchers and many of them had been forced to reduce their ratę of work during some period of time. There were no

Fig. 11 Sawing at a bandsaw requires frequent forward bending, stariing from slight forward f!exion of the irunk

signs that the few older butchers had morę troubles than the younger ones; this may be a reflection of the ‘healthy worker effect*. however.

The bódy-areas in which the butchers experienced a high load during work corresponded with the areas of pain, although the frequency of experience of load was larger. This can indicate a risk that morę butchers will derelop disorders from the parts that are loaded during work, sińce those who do not experience pain might not have worked long enough.

By analysis of the working tasks we could identify several that caused high loads on the body parts in which pain or trouble had developcd. High stresses were found to have the foltowing main causes which occurred together in most work situations:

(1)    £xertion of high forces when cutting the meat.

(2)    Frequent — and often heavy — manuał matenals handiing

(3)    Bad working postures.

The resistance when cutting is due to the toughncss of the meat which is influenced by several factors related to storage conditions - eg, temperaturę, age, dryness — and to the history of the animals — eg, care, feed stuff and exercise. The large size of the pieces that are being cut also leads to high knife forces which are parlicularly strenuous when the cutting isdone in positions in which exertion of maximum force is rcduced. The arm is often lifted out from the body for extendcd periods of time, which leads to a static load on the muscles.

At the same time these muscles are working dynamically together wirh others in the cutting movements. The dynamie work is. however, often so freąuent that it is comparable with static work because the pauses between the contractions are too short for the muscles to relax and recover. The consequence is that the muscles may not relax

48 Applied Ergonomie* March 1987