Analysis of neck and shoulder postures, and muscle activities relative to perceived pain during laptop computer use at a low-height table, sofa and bed.

BACKGROUND: Laptop computers are used in various places and situations. The number of laptop users experiencing musculoskeletal disorders (MSDs) has increased drastically due to, in part, inappropriate workstations. OBJECTIVE: To investigate the neck and shoulder postures, and muscle activity relative to perceived pain when using the laptop at a low-height table, sofa, and bed. METHODS: Twenty male participants aged 18-25 years were randomly assigned to perform laptop computer operation at 3 workstations for 10 minutes during which neck and shoulder angles, muscle activity, and pain were recorded by using an Electrogoniometer, Electromyography (EMG), and visual analog scale (VAS), respectively. RESULTS: Neck flexions when working at the sofa (18.6°±12.2°) and bed (17.2°±10.5°) were significantly (p < 0.05) greater than that at the low-height table (7.8°±6.5°). However, shoulder flexion when working at the low-height table (28.2°±13.0°) was significantly (p < 0.05) greater than that at the sofa (13.8°±8.6°) and bed (10.91°±7.8°). Working at the low-height table caused the shoulder flexor muscle activity to be significantly (p < 0.05) higher than working at the sofa and bed. Neck pain was reported during laptop computer use at the sofa and bed, and upper back pain when working at the low-height table. CONCLUSIONS: High neck flexion and pain were found while working at sofa and bed, whereas high muscle activity at shoulder and upper back pain were found while working at the low-height table.