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heights for standing work have bccn givcn by Grandjean (1979). He used the elbow hcighl as rcfcrcncc Icvcl and rccommcndcd three dłftfrem height ranges dcpending on whether (he working task is dcmanding precision or if it is ‘light’ or ^łhcavy*. For ‘light’ work, thc working hcighl should be 10-1S cmbclow elbow hcight. and for *heavy* work the hcight should be 15—40 cm below elbow height. The butchers* working tasks at the labie are both light and heavy and the materials they handle vary in form and size.

One would think that the worker would know best which working height is the best for his work. In our tests wc fet the butchers choose one labie height. Subjective ratings show that three of the five butchen considcred the self-chosen height as the most comfortable one compared with 5 cm lower and 5 cm higher tablc height. This height varied for these three butchers within 18 and 27 cm below elbow height. A probablc reason for this large variation could be that the self-chosen height tumed out to be the height that the butcher was used to, and therefore was felt most comfortable. The other cvaluation methods used showed, however, that the best height for four of the five butchers was between 18 and 22 cm below elbow height. The results from the test scries at the workplaces show that 12 of 15 butchers found their best working height between 17 and 20 cm below elbow height.

SeveraJ butchers were sceptical of the tilted surface, which became obvious on the comfort-discomfort scalę; only six of 20 thought that thc tilted surface was the best. The body map eva!uatk>n, on the other hand. showed that the number of loaded body areas was least with the tilted surface, whensummedoverall the five butchers in the laboratory tests.

The analysżs of the videotapes showed clearly that one fixed optimal working height in butchering was not to be found because different heights load different parts of the body. Thus, the height at which the back is most unloaded gives morę load on the shoulders, and vice versa. Because there is no generał agreement on how to value loads on different body parts against each other, the working height must be decided upondepending on whether the concern is to unload the back or the shoulders. However, in ihe rangę 17—22 cm below elbow height, the loads on the back and the shoulders were quite Iow; so this can bc recommended as a good compromise (see Fig. 4).

Thus, for cutting meat an individuai table height is chosen within the rangę 17—22 cm below elbow height, the lower limit when the concern is to minimisc the load on the shoulders, the upper limit when it is to minimisc the load on the back. A good practice would be to alter the height within this intcnral during the workday to altemately unload the shoulders and the back. The fuli efTect of this is probably obtained only if the varia(ion is done automatically and not by the butcher himself.

As habit has an influence on the feeling of comfort. the working height that the butcher is used to is felt to be morę comfortable than one that he is not used to. It is therefore important that the time for testing out the right table height is long enough to minimisc thc influence of habit. It is also important to make elear how a too high and too Iow table height afTect the body load so that the user of the table pays attemion to this whiie :es:ing out his optinul Labie height.