Mork, P.J., & Westaard, R.H. (2009). Back posture and low back muscle activity in female computer workers: A field study. Clinical Biomechanics, 24, 169-175.

Aim. This study examined the relationship between posture, use of back muscles, and low back pain.         

Method. 21 women (mean age= 43 years + 10) who worked primarily with computers were measured on posture (pelvis and trunk), muscle activity (surface electromyography, or sEMG), thigh angle (to determine sitting vs. standing), and hourly back pain during work (4.9-7 hours) and leisure time.

Results. The group of muscles responsible for sitting was more engaged during upright sitting versus slouching. While standing, pelvic angle and upper trunk angle predicted activity low back muscle activity. While sitting, the pelvic angle most strongly predicted low back muscle use. Low back pain increased throughout the day and decreased during leisure time. Finally, more low back pain was associated with less low back muscle engagement.

Conclusion. Healthy sitting postures might engage slight low back curvature (lordosis), supported by the both pelvis posture and engaging low back muscles.