Posture, acceptability and energy consumption on a tiltable and a knee-support chair

Sitting postures on a knee-support (Balans®) chair and a tiltable chair were investigated with 12 healthy subjects during office work and simulated assembly work. After at least 3 weeks' adaptation to each chair, the subjects were investigated for 1 hour on each chair in stratified sequence. Postures were evaluated by means of a statometric method. Spinal load was further estimated by measuring stature shrinkage over each sitting period. Energy consumption was roughly assessed by pulse measurements. Finally, subjective acceptability was rated by a 5-point scale. Posture effects of the Balans® chair, taken in relation to the tiltable chair, were primarily a forward tilt of the pelvis and a change toward lumbar lordosis. Secondly, the trunk was vertical compared to the slightly backward-inclined position in the tiltable chair. The head was most vertical in the Balans® chair. No effect on spinal shrinkage or pulse was observed. The subjective rating seemed to favour the tiltable chair if used over longer periods. However, the Balans(®) chair may be a good alternative for some seated periods and special tasks.