Moffet H, Hagberg M, Hansson-Risberg E, Karlqvist L
Department of Rehabilitation, Faculty of Medicine, Laval University and Center for Interdisciplinary Research in Rehabilitation and Social Integration, 525, Blvd Hamel, B-77, Que., Canada G1M 2S8.
Clin Biomech (Bristol). 2002 Jun;17(5):368-75. doi: 10.1016/s0021-9290(02)00062-3.
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.
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.
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.
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.
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.
评估两种笔记本电脑设计（有或无掌托）以及两种工作场景（在桌面或腿上）对颈部和上肢姿势、肌肉活动及工作效率的影响。
八名健康受试者进行了一项时长15分钟的标准化打字任务。在每次测试的最后5分钟，通过三维视频系统捕捉颈部、上臂和躯干姿势，用双轴电子测角仪测量手腕运动，并记录颈部和上肢四块肌肉的肌肉活动。
在相同场景下比较两种笔记本电脑设计时，仅观察到姿势、手腕位置和工作效率方面的微小差异。而在比较两种场景（桌面或腿上）时，发现了更大的差异。在桌面场景中，受试者头部前屈较少，躯干后倾和手腕伸展较少，但上臂抬高较多。在桌面场景中还发现斜方肌和三角肌的肌电图（EMG）水平较高，而手腕伸肌的EMG水平较低。
我们的研究结果并不支持某一种特定的笔记本电脑设计，因为仅发现了身体暴露方面的微小差异。然而，工作区设置影响了身体暴露变量，并且被确定为在进行笔记本电脑工作时需要考虑的主要决定因素，尽管没有发现理想的情况。在桌面场景中，肩部区域似乎受到更大的身体（肌肉和关节）限制，而在腿上场景中，头颈和手腕部分似乎承受更大压力。
尽管尚未对笔记本电脑工作中的身体暴露以及不同笔记本电脑设计的影响进行系统评估，但笔记本电脑仍经常被使用。更好地理解这些因素可能有助于为笔记本电脑用户制定一些建议。
