Abstract. [Purpose] This study investigated the effects of postural angle on back muscle activity during a computer
task in aging women. [Subjects] Seventeen women ≥50 years old participated. [Methods] The participants
were instructed to perform computer-related tasks for 20 minutes on a workstation that simulated typical office
working conditions. Back posture was measured from the measured trunk and pelvic angles. Electromyography
activities were recorded simultaneously from the cervical erector spinae, longissimus, and multifidus muscles. [Results]
The lowest mean percentages of maximum voluntary contraction for the cervical erector spinae and longissimus
muscles were obtained when the upper trunk and pelvic angles were between 0° to −5° from the sagittal plane.
The back muscle activities increased as the upper trunk and pelvic angles exceeded 0°. Statistical analysis showed
significant correlations between upper trunk angle and cervical erector spinae and longissimus muscle activities.
Similarly, pelvic angle was significantly correlated with cervical erector spinae and multifidus muscle activities.
[Conclusion] A neutral back posture minimizes muscle activities in aging women performing computer tasks.
Key words: Postural angle, Muscle activity, Aging