The Spinal Curvature of Three Different Sitting Positions Analysed in an Open MRI Scanner

Abstract

Sitting is the most frequently performed posture of everyday life. Biomechanical interactions with office chairs have therefore a long-term effect on our musculoskeletal system and ultimately on our health and wellbeing. This paper highlights the kinematic effect of office chairs on the spinal column and its single segments. Novel chair concepts with multiple degrees of freedom provide enhanced spinal mobility. The angular changes of the spinal column in the sagittal plane in three different sitting positions (forward inclined, reclined, and upright) for six healthy subjects (aged 23 to 45 years) were determined using an open magnetic resonance imaging (MRI) scanner. An MRI-compatible and commercially available office chair was adapted for use in the scanner. The midpoint coordinates of the vertebral bodies, the wedge angles of the intervertebral discs, and the lumbar lordotic angle were analysed. The mean lordotic angles were 16.0 ± 8.5° (mean ± standard deviation) in a forward inclined position, 24.7 ± 8.3° in an upright position, and 28.7 ± 8.1° in a reclined position. All segments from T10-T11 to L5-S1 were involved in movement during positional changes, whereas the range of motion in the lower lumbar segments was increased in comparison to the upper segments.

In VivoSpinal Posture during Upright and Reclined Sitting in an Office Chair

“…Similar results were demonstrated in the lower back (S1-TH11) for upright, reclined, and forward inclined sitting by Baumgartner et al [12]. Although the two sitting positions in our set-up were clearly defined by the shape of the backrest, high inter-subject variability of the shape of the upper spinal segments was observed for both sitting positions.…”

“…The data analysis was carried out using the techniques described by Baumgartner et al [12]. The evaluation was performed on the MR image closest to the median plane of the body using MegaCAD 2D (Version 2011, MegaCAD-Center GmbH, Oberweningen, Switzerland).…”

Relevance of adding a triangular dynamic cushion on a traditional chair: A 3D-analysis of seated schoolchildren

“…In fact, dynamic SP could improve the feeding of the inter-vertebral discs due to compression/decompression movements (Claus et al, 2009). In addition, it might reduce muscular weakening induced by muscular inactivity in a long-term static SP (Baumgartner et al, 2012) and improve lumbar proprioception (Dolan and Green, 2006) and thereby reduce the risk of injuries (Hodges and Moseley, 2003). Our results demonstrate that children move significantly more when sitting on the cushion than when sitting on "traditional" furniture.…”

“…In fact, in a purely static SP, the flow of fluid from the discs may be reduced or reversed (Claus et al, 2009). In addition, prolonged static SP is associated with muscular inactivity that could induce muscular weakening (Baumgartner et al, 2012) with an eventual impact on lumbar proprioception (Dolan and Green, 2006) and consequently more risk of injuries (Hodges and Moseley, 2003).…”

Application of Machine Learning Approaches for Classifying Sitting Posture Based on Force and Acceleration Sensors

“…These authors also highlighted the difference in muscular activity in the back between the different sitting positions and the different inclination angles of the backrest [10]. Furthermore, while changing position from an upright to a reclined as well as to a forward inclined sitting position, the chair user can adapt the position of the intervertebral discs [12, 13]. Thus, most chair manufacturers now provide sitting facilities that incorporate a variety of sitting positions.…”