Ergonomic on-the-job training of assembly workers. Arm-neck-shoulder complaints drastically reduced amongst beginners.

Assembly workers at a chain saw factory in Sweden were ergonomically instructed with the purpose of adjusting their movement patterns so that the muscular load on their upper extremities was kept below the critical level, defined as 10% of the maximum voluntary contraction. The study included two separate categories of subjects: new workers without previous experience of assembly work, and workers with at least one year's experience. As a result of the ergonomic instruction, the number of days lost through arm-neck-shoulder complaints was reduced by half in the test group consisting of new workers, compared with the corresponding control group with no ergonomic training. Amongst the experienced workers, however, the difference between the test group and the control group was statistically non-significant. The study showed that ergonomic monitoring and training are necessary to benefit fully from improved workplaces and tools. Considering the results accomplished amongst the new workers and given the extent of sick leave for the upper extremities, it seems that ergonomic interventions to prevent arm-neck-shoulder complaints at an early stage are extremely worthwhile.