Electromyography of the upper limbs during computer work: a comparison of 2 wrist orthoses in healthy adults.

OBJECTIVE

To examine the effect of wrist orthoses on the electromyography activities of the extensor carpi ulnaris, flexor digitorum superficialis, and fibers of the upper trapezius muscles during computer work.

DESIGN

A randomized, 3 x 2 factorial design: orthoses (no orthosis, wearing a custom-made orthosis, wearing a commercial orthosis) and tasks (typing, using the mouse).

SETTING

Laboratory for biomechanics and rehabilitation.

PARTICIPANTS

Healthy university students (N=23), ranging from 18 to 26 years of age.

INTERVENTION

Study volunteers performed standardized tasks such as typing and using the mouse while wearing 1 of 2 types of wrist orthoses or no orthosis.

MAIN OUTCOME MEASURES

We used surface electromyography and considered 100% maximum voluntary contraction to represent the amplitude of electromyographic activity.

RESULTS

We observed a significant increase in the electromyographic activity of the trapezius (P<.05) with the use of orthoses. No significant difference was observed in the activities of the flexor digitorum superficialis or extensor carpi ulnaris in participants who typed with or without orthoses (P>.05). However, when the participants used the mouse, the extensor muscle presented an increase in activity with both orthoses, and the same pattern was observed in the flexor muscle when the volunteers used the custom-made orthosis.

CONCLUSIONS

Wrist orthoses affected the muscle activities in the upper limbs of healthy adults who were using a computer. Electromyographic activity increased in the trapezius when the subjects used either type of orthosis, and the same pattern was observed in the extensor carpi ulnaris when the subjects used the mouse. The flexor digitorum superficialis presented an increase in activity only when the subjects worked with the mouse and used a custom-made splint.