Abstract
OBJECTIVES: This study concerned the influence of 6 positions of the
computer mouse on the work table on posture, muscular load, and
perceived exertion during text editing. METHODS: An optoelectronic
3-dimensional motion analysis system was used to register the postures
of 10 men and 10 women using video display units. Muscular load
was also registered (with electromyography), as was perceived exertion
(with rating scales). RESULTS: A neutral posture with a relaxed
and supported arm showed the least perceived exertion, and the electromyographic
results showed low activity in both trapezius muscles in this position.
Short operators (all women) showed a numerically higher activity
in the 4 examined muscles than the tall operators (all men, except
1). This finding could be related to lower muscle force among women
and to anthropometric differences, which also influence biomechanic
load moments. Narrow-shouldered operators (8 women and 1 man) and
short operators worked with larger outward rotation and abduction
of the shoulder in a position of the mouse lateral to the keyboard
than the broad-shouldered (7 men and 2 women) and tall operators
did. Arm support markedly reduced muscle load in the neck-shoulder
region among the operators. CONCLUSIONS: The operators using video
display units in this study preferred to use the mouse on a table
in a close to relaxed, neutral posture of the arm in combination
with arm support. Short and narrow-shouldered operators worked in
more strenuous postures of the arm when the mouse was located lateral
to the keyboard. Clinical Trial, Journal Article; In English; Finland;
MEDLINE
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