EFFECT OF WORK STATION DESIGN ON SITTING POSTURE IN YOUNG-CHILDREN

The purpose of the study was to compare muscular activity levels and s itting posture displayed by 10 children (mean age = 4.7 years) when pe rforming tracing tasks while seated at a traditional work station (lev el desk top, 5-degrees backward sloping seat) and at an ergonomically designed work station (15-degrees sloping desk top, 15-degrees forward sloping seat). EMG profiles of latissimus dorsi (LD), erector spine ( ES), and superior trapezius (ST) were sampled using Medi-trace disposa ble surface electrodes for 10 min on the non-dominant side. Muscle act ivity was sampled (1000 Hz) every 2 min for 5000 ms while the subjects performed the tracing tasks at each station. Raw EMG signals of the f ive trials for each muscle were processed by removing signal offset, f ull-wave rectification, and integration. The subjects' posture was mon itored from a lateral view using a Panasonic VHS video camera while th e children were seated at each work station. Neck flexion angle and th e angle between the torso and thigh (hip angle) were manually sampled from the video images each 1 min as an indication of the posture adopt ed by the subjects during the tracing tasks. Use of t-tests for depend ent means indicated that there was no significant difference in either mean ES or ST muscle activity as a function of work station design. H owever, subjects demonstrated significantly less LD activity when seat ed 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). Whe n seated at the ergonomically designed work station, subjects demonstr ated less neck flexion (mean = 34.4-degrees) and a significantly large r hip angle (mean = 107.8-degrees, t = -3.46, p = 0.003) than when sea ted at the traditional work station (neck flexion = 38.7-degrees, hip angle = 95.5-degrees). It was concluded that use of the ergonomic work station could assist in maintaining a more efficient anatomical align ment of young children when sitting and writing.