CASE STUDIES
If you would like to understand how sedentary modern day office computing work contributes to fatigue, lower concentration and all round general muscle tension, these two case studies into the benefits of armrests and Ergorest forearm supports may be of interest to you...
UNIVERSITY OF KUOPIO
P.O. BOX 6
FIN- 70211 KUOPIO
Tel: +358 17 162 211
Forearm rests improve sedentary work performance
It has been found that typewriting and computer terminal work tend to cause more neck, shoulder and arm complaints and functional ailments, than varied office work. Work requiring concentration and precision necessitates maintaining head, neck, shoulders and
forearms in a constant and asymmetric position. This creates constant muscle tension in those areas, expending energy and hampering blood circulation in the muscles. Even simple movements and keeping the forearms slightly above lap level have been found to cause tension and tiredness in the electrical behavior of the shoulder muscles.
It has been concluded that the shoulder muscles can only withstand static work not exceeding 2% of the contraction capacity of the muscles. In typewriting and computer terminal work, however, the shoulder region has been found to struggle with work up to 20-30% of contraction capacity. This tension, predominantly on the neck and shoulder muscles, in tasks requiring one to be deft with one's fingers, induces a constant struggle to maintain the proper body position and, as such, is not directly connected with the work effort in question. It can, therefore, be eliminated with ergonomic adjustments and aids.
An international research project is underway in the Department of Physiology at the University of Kuopio and we have studied the tension in the shoulder muscle region caused by computer terminal work and the effect on it when the weight of arms is eliminated. We
have conducted research into the applicability of various forearm rests as tension reducing agents in shoulder muscles during sedentary work. Tests in the laboratory and in real working conditions have proved that forearm rests considerably reduce shoulder muscle tension during sedentary work. It seems that the best effects are obtained in conjunction with proper ergonomics. Studies abroad, too, have found that eliminating the weight of arms through suspension or forearm rests can lead to a decrease in tension on the neck, shoulder and back muscles during sedentary work. Thus eliminating the weight of arms in a proper way can considerably reduce constant muscle tension in the neck-shoulder region and prevent and ease tension during sedentary work.
Teuvo Sihvonen, MD
Department of Physiology
University of Kuopio
UNIVERSITY OF KUOPIO
P.O. BOX 6
FIN- 70211 KUOPIO
Tel: +357 17 162 211
Long-term effects of Ergorest forearm rests on subjective complaints in office
work: research findings
The control group of the study consisted of 22 people , 24 people used the Ergorest forearm rest, and 16 people did muscle stretching and exercises. In addition, a group of old forearm users (9 persons) was formed, with a control group of 7 people. The test groups were similar: they were engaged in similar amounts of computer terminal work (2.6 - 3.1 hrs/day ), the amount of light exercise was the same, and no-one was undergoing medication or medical treatment.
The Ergorest forearm rest group was taught how to use the Ergorest forearm rests for entering information and typing with computers, and few basic ergonomic aspects of the proper working position were explained to them. The exercise group did the given isometric and - towards the end of the study period - the dynamic exercises for the neck-shoulder region on a daily basis. The control group continued their work as before. All of the people in the study filled out a complaint diary, recording their feelings and complaints and working hours in the manner they were told at the start of the study. Subjective complaints had to be evaluated on a scale 0 - 10, ranging from harmless to extreme discomfort. Mobility, pain spots and muscle tension of the neck-shoulder region were under scrutiny for about three months.
Comparing the Ergorest forearm rest users with the control group, the differences between the subjective complaints based on the diaries can roughly be listed as follows: the control group had 50% more neck and shoulder complaints during the study than the Ergorest forearm rest group.
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The control group also reported tiredness in arms 100% more frequently than the Ergorest forearm rest users. Numb arms occurred in the control group 50 times more frequently than in the Ergorest forearm rest group. Tiredness in the legs occurred 4 times more frequently, back pain 2.5 times more frequently and eye strain 50% more frequently in the control group than in the Ergorest forearm rest group. There was little difference in frequency of headaches, but the Ergorest forearm rest group did experience headaches 20% less frequently than the control group.
Comparing the Ergorest forearm rest group with the exercise group and the two groups with the control group, it can be stated that complaints in the neck-shoulder region decreased by about the same amount among the Ergorest forearm rest users and the exercise group (10% fewer complaints in the exercise group than in the Ergorest forearm rest group). The exercise group reported tiredness in arms 50% less than the control group (compared with the Ergorest forearm rest users the effect was 50% less, see the previous paragraph). With exercising, tiredness in arms dropped to one fifth compared with the control group, but it still occurred almost 10 times more frequently than that reported among the Ergorest forearm rest users. Back pain was reported 30% less frequently among the exercise group than among the Ergorest forearm rest users. With exercising, tiredness in legs dropped 50% but still occurred twice as frequently in the exercise group than in the Ergorest forearm rest group. Eye strain was reported 30% more frequently in the exercise group than in the control group, i.e. this complaint was somehow more pronounced in the exercise group. The exercise group did not report any other possible complaints, which, on the other hand, many members of the control group and some members of the Ergorest forearm rest group did report. Perhaps the general well-being in the exercise group was subjectively better; even though those in the group did report some complaints when asked about them.
Among the earlier forearm users the effect of the forearm rests was smaller: only the occurrence of headaches and eye strain dropped somewhat. The occurrence of complaints in the neck-shoulder region did not drop subjectively, and neither did tiredness in arms.
Headaches occurred 50% less frequently among the forearm rest users than in the control group. There was more back pain and tiredness in legs reported among the earlier forearm rest users. Eye strain was reported 25% less frequently among the earlier forearm rest users than in their control group.
In the Ergorest forearm rest group, the mobility of the shoulder joints and the flexibility of the cervical spine increased and, in addition, tenderness of the skull base and thoracic cage muscles decreased during the study. Tension in the trapezius (EMG test) dropped considerably during the period of Ergorest forearm rest use, particularly on the right side where the work was found to be more static.
Teuvo Sihvonen, MD
Department of Physiology
University of Kuopio