Perceived body discomfort and trunk muscle activity in three prolonged sitting postures

Abstract

[Purpose] This study aimed to investigate the perceived discomfort and trunk muscle activity in three different 1-hour sitting postures. [Subjects] A repeated-measures design study was conducted on 10 healthy subjects. [Methods] Each subject sat for an hour in three sitting postures (i.e., upright, slumped, and forward leaning sitting postures). Subjects rated perceived body discomfort using Borg’s CR-10 scale at the beginning and after 1 hour sitting. The electromyographic activity of the trunk muscle activity was recorded during the 1-hour period of sitting. [Results] The forward leaning sitting posture led to higher Borg scores in the low back than those in the upright (p = 0.002) and slumped sitting postures (p < 0.001). The forward leaning posture was significantly associated with increased iliocostalis lumborum pars thoracis (ICL) and superficial lumbar multifidus (MF) muscle activity compared with the upright and slumped sitting postures. The upright sitting posture was significantly associated with increased internal oblique (IO)/transversus abdominis (TrA) and ICL muscle activity compared with the slumped sitting posture. [Conclusion] The sitting posture with the highest low back discomfort after prolonged sitting was the forward leaning posture. Sitting in an upright posture is recommended because it increases IO/TrA muscle activation and induces only relatively moderate ICL and MF muscle activation.

Development of Ergonomics Guidelines for Improved Sitting Postures in the Classroom among Malaysian University Students

“…In particular, students sitting with an upright pose for more than an hour appear to be users that most likely suffer from Lower Back Pain (LBP) due to compression of the tissue in the lumbar spine (Rajaratnam and Janwantanakul, 2015).…”

“…A chair with an armrest would provide a higher comfort level in such a way where one can sit with an upright shoulder-relaxed posture and place the arms on the armrest (Rajaratnam and Janwantanakul, 2015).…”

“…Regarding prolonged sitting, Cardon et al (2004) stated that maintaining the same sitting posture for more than 30 min is considered to be prolonged sitting and that the subjects are exposed to MSD risk factors related to the lower spine. Rajaratnam and Janwantanakul (2015) mentioned that a long duration of poor postures while sitting most likely causes musculoskeletal disorders in the neck, upper back, lower back and the hips.…”

The Effect of Chair Backrest on Respiratory Function in Prolonged Sitting Position

“…[2][3][4] In addition, prolonged sitting changes body posture, and these in turn affect trunk muscle activity, such as, of the iliocostalis lumborum, multifidus, internal oblique, transverse abdominis muscles. 5 Abdominal muscles play roles in respiration, 6,7 and their activities affect posture, which suggests respiratory function is probably associated with posture. 8 In a previous study, it was suggested that an upright sitting posture is associated with higher internal oblique, transverse abdominis and iliocostalis lumborum muscle activities as compared with a slumped sitting posture.…”

Time-varying Changes in Pulmonary Function with Exposure to Prolonged Sitting

“…In addition, previous studies reported that prolonged sitting has an adverse influence on musculoskeletal functions. For example, it brings about decreases in intervertebral disk health, active lumbar range of motion, and spinal musculature activity, and an increase in passive stiffness 6, 7, 8, 9.…”