Abstract
Objective. To evaluate the impact of two laptop designs (with or without palm rest) and two
work situations (on desk or lap) on neck and upper limb posture, muscle activity and
productivity.
Design and methods. Eight healthy subjects performed a standardized typing task of 15 min duration. During
the last 5 min of each test, the neck, upper arm and trunk postures were captured
by a three-dimensional video system, wrist motion was measured by a biaxial electrogoniometer
and muscle activity of four neck and upper limb muscles was recorded.
Results. Only minor differences in postures, wrist positions and productivity were observed
when comparing the two laptop designs in the same situation. Larger differences were
found when comparing the two situations (desk or lap). In the desk situation, the
subjects bent their heads forward less, had less backward trunk inclination and wrist
extension, but more elevation of the upper arm. Higher electromyographic (EMG) levels
in the trapezius and deltoid muscles and lower EMG levels in the wrist extensors were
also found in the desk situation.
Conclusions. Our findings do not favor one particular laptop design because only small differences
in physical exposure were found. However, the workstation set up influenced the physical
exposure variables, and was pinpointed as the main determinant to be considered when
doing laptop work even-though no ideal situation was found. Greater physical (muscular
and articular) constraints seem to be imposed to the shoulder region in the desk situation
whereas the head-neck and wrist segments appear to be more stressed in the lap situation.Relevance
Laptop computers are often used although the physical exposure in laptop work and
the impact of different laptop designs have not been systematically assessed. A better
understanding of these factors may help formulate some recommendations for laptop
users.
Keywords
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Article info
Publication history
Accepted:
April 2,
2002
Received:
April 7,
1998
Identification
Copyright
© 2002 Elsevier Science Ltd. Published by Elsevier Inc. All rights reserved.
