The issue of sitting ergonomics is becoming increasingly important, as about 70% of all employees work in Sweden every day at a computer-based workstation and 15% exclusively perform computer work during their working day, and these numbers increase each year. The vast majority of this work is performed seated on a conventional office chair with a backrest. Prolonged sitting has been identified as a serious metabolic health problem due to several pathogenic mechanisms linking muscular inactivity to increased health risks.
The authors aim with this study was to compare the biomechanical characteristics of sitting on a stool without a backrest (so as to encourage active sitting), sitting on a conventional office chair and standing in healthy participants. Thirteen healthy participants performed a keyboard-writing task during four (stable and unstable) sitting conditions and standing. Body segment positions and posture, postural sway and muscle activity of neck and trunk muscles were assessed with a motion capture system, a force plate and surface electromyography. The results showed that body segment positions, postural sway and trunk muscle activity were relatively similar for the stools without backrests compared with standing. All sitting conditions showed lower vertical upper body alignment, less anterior pelvic tilt and larger hip angles, compared with standing (p ¼ 0.000).
Surprisingly, less postural sway and less muscle activity were observed during the conditions that encourage active sitting, compared with sitting on a conventional office chair.