Effect of different sitting postures on lung capacity, expiratory flow, and lumbar lordosis

Arch Phys Med Rehabil. 2006 Apr;87(4):504-9. doi: 10.1016/j.apmr.2005.11.031.


Objective: To investigate the effect of sitting posture on lung capacity and expiratory flow (LC-EF) and lumbar lordosis.

Design: Repeated measures on 1 group of subjects in 4 postures.

Setting: Laboratory.

Participants: Seventy able-bodied volunteers.

Interventions: Postures were assumed randomly: normal, with full ischial support and flat lumbar support; slumped, with the pelvis positioned in the middle of seat while leaning against the backrest; against the back part of the seat without ischial support (WO-BPS), with partially removed ischial support and an enhanced lumbar support; and standing.

Main outcome measures: For LC-EF, forced vital capacity, maximum forced expiratory flow, forced expiratory volume in 1 second, and peak expiratory flow; and lumbar lordosis.

Results: All LC-EF measures in standing were significantly superior to those in slumped and normal sitting, and 4 measures were significantly higher than in WO-BPS. In slumped sitting, LC-EF significantly decreased from that in normal sitting. WO-BPS sitting significantly increased 4 of the LC-EF measures from those in the normal sitting. Lumbar lordosis was the highest in standing and progressively decreased in WO-BPS, normal, and slumped sitting.

Conclusions: Slumped sitting significantly decreased LC-EF and lumbar lordosis. Because it increases the lumbar lordosis and promotes LC-EF, the WO-BPS posture may be a better seating option for people sitting for a prolonged time.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Analysis of Variance
  • Female
  • Humans
  • Lordosis / physiopathology*
  • Lumbar Vertebrae / physiology*
  • Lung Volume Measurements*
  • Male
  • Middle Aged
  • Peak Expiratory Flow Rate / physiology*
  • Posture / physiology*
  • Wheelchairs*