Effect of work station design on sitting posture in young children

The purpose of the study was to compare muscular activity levels and sitting posture displayed by 10 children (mean age =4·7 years) when performing tracing tasks while seated at a traditional work station (level desk top, 5° backward sloping seat) and at an ergonomically designed work station (15° sloping desk top, 15° forward sloping seat). EMG profiles of latissimus dorsi (LD), erector spine (ES), and superior trapezius (ST) were sampled using Medi-trace disposable surface electrodes for 10min on the non-dominant side. Muscle activity was sampled (1000 Hz) every 2min for 5000 ms while the subjects performed the tracing tasks at each station. Raw EMG signals of the five trials for each muscle were processed by removing signal offset, full-wave rectification, and integration. The subjects' posture was monitored from a lateral view using a Panasonic VHS video camera while the children were seated at each work station. Neck flexion angle and the angle between the torso and thigh (hip angle) were manually sampled from the video images each 1 min as an indication of the posture adopted by the subjects during the tracing tasks. Use of f-tests for dependent means indicated that there was no significant difference in either mean ES or ST muscle activity as a function of work station design. However, subjects demonstrated significantly less LD activity when seated at the ergonomic work station (mean = 20·9 V ms) compared with the traditional work station (mean = 24·4 V ms, t = − 2·88, p = 0·018). When seated at the ergonomically designed work station, subjects demonstrated less neck flexion (mean = 34·4°) and a significantly larger hip angle (mean = 107·8°, t= − 3·46, p = 0·003) than when seated at the traditional work station (neck flexion = 38·7°, hip angle = 95·5°). It was concluded that use of the ergonomic work station could assist in maintaining a more efficient anatomical alignment of young children when sitting and writing.