Bahar Shaghayeghfard - Department of Physiotherapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
Mohammad Taghi Karimi - Department of Physiotherapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
Leila Abbasi - Department of Physiotherapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
Mohsen Razeghi - epartment of Physiotherapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Iran

Background: The effect of position and gender on chest movements and respiratory volumes is controversial and investigated in only a few studies.Objective: This study aimed to investigate the effects of position and gender on the breathing pattern during four different positions in healthy individuals.Material and Methods: In this cross-sectional study, twenty-eight (۱۴ males, ۱۴ females) healthy individuals participated aged ۲۰-۴۵ years. The optoelectronic plethysmography (OEP) method was used for the three-dimensional evaluation of chest wall motions and the compartmental analysis of the breathing pattern in supine, sitting, standing, and active straight leg raised (ASLR) positions. Volume changes in different parts of the chest wall were also measured.Results: Position affected total and compartmental respiratory volumes in both genders. Respiratory volumes decreased in the supine position compared to sitting and standing. Total and abdominal respiratory volumes also decreased in females when comparing supine positions with the ASLR. A higher pulmonary rib cage contribution was identified in females, and males exhibited higher abdominal rib cage volume compared with females. Conclusion: The breathing pattern was affected by position and gender, and the respiratory volumes increased in more upright positions, perhaps due to a greater gravitational load. The ASLR decreases the respiratory volume, which is probably due to increased postural demand.

Plethysmography, chest wall, Lung Volume Measurements, gender differences, Position