Rating of the overall preceived exertion, and the ratings of the arms, increased more quickly when working at the 'standard' checkout. This could be due to the effect of raising the arms to lift the load onto the high rear collection shelf at that checkout. Rodahl(1989) points out that tasks requiring the arms to be raised above the shoulder result in relatively high cardiovascular strain and the rapid onset of fatigue.
Although OWAS is not sensitive to prolonged begging of less than 20, which was observed to be the main type of bending during the study, it was nevertheless considered to be an appropriate tool to highlight postural load between the checkouts. For the full checkout job, there were significantly more bent, twisted, and bent and twisted postures, but significantly less working posture observed at the 'short' checkout. The differences were even more noticeable during the packing and transferring task. The high number of bent, twisted, and bent and twisted back postures observed at the 'short' checkout indicate that a greater musculoskeletal load is associated with that checkout design. Nineteen percent of the postures observed at the 'short' checkout, during the bag-transferring stage, were rated by OWAS as requiring remedial action 'in the near future' During the bag-transferring task, the 'standard' checkout had significantly more 'arms' raised above shoulder' postures These postures illustrate the greater biomechanical load associated with having to lift the bags onto the high rear collection shelf of this checkout.