The estimation of pulmonary functions in various body postures in normal subjects


  • Lathadevi. V. Ganapathi Department of Physiology,PSG Institute of Medical Sciences and Research, Coimbatore, Tamil Nadu, India
  • Sabari Vinoth III MBBS student, PSG Institute of Medical Sciences and Research, Coimbatore, Tamil Nadu, India



Postural changes, Pulmonary functions, Vital capacity


Background: The frequently measured index of pulmonary function is vital capacity which gives useful information about the strength of respiratory muscles and other aspects of lung function. The purpose of the study was to investigate changes that occur in vital capacity in different postural attitudes like standing, supine, right lateral, left lateral positions compared with the reference position such as upright sitting in normal subjects.

Methods: Young non-smoker healthy male medical students (n=20, age 19-22 years) of PSG Medical College participated as volunteers in this study. Pulmonary function tests like forced vital capacity (FVC), Forced Expiratory Volume in one second (FEV1), FEV1 to FVC% i.e. (FEV1%) was recorded in various postures using computerized spirometer in BIOPAC systems, Inc., MANBSL3S, student version, following the standard procedure.

Results: A repeated measure ANOVA-multiple comparison study revealed FVC, FEV1 and FEV1% values in standing posture was significantly higher than supine, sitting, right and left lateral positions.

Conclusions: Naturally, in standing posture factors contributing to increased vital capacity are increased, vertical diameter of thorax which increases thoracic capacity volume and lung compliance increasing lung volume.


Manning F, Dean E, Ross J, RT A. Effects of Side Lying on Lung Function in Older Individuals Phys Therap. 1999;79:456-66.

Dean E. Effect of body position on pulmonary function. Phys Ther. 1985;65:613–8.

Zack MB, Pontoppidan H, Kazemi H. The effect of lateral positions on gas exchange in pulmonary disease: a prospective evaluation. Am Rev Respir Dis. 1974;110:49–55.

Dean E. Invited commentary on “Are incentive spirometry, intermittent positive pressure breathing, and deep breathing exercises effective in the prevention of postoperative pulmonary complications after upper abdominal surgery? A systematic overview and meta-analysis.” Phys Ther. 1994;74:10–5.

Biopac Student Laboratory Manual; part no MANBSL3S: Lesson 12, pg. 1-21; Lesson 13, pg. 1-25.

A K Jain, Manual of Practical Physiology; II edition, pg 180.

Sarada Subramanyam and K. Madhavan kutty, Text Book of Human Physiology, 6th edition pg. 213 & 258.

American Thoracic Society. Standardisation of spirometry: 1994 update. Amer Jou of Resp & Critical Care Med. 1995;152:1107-36.

Wade OL, Gilson JC. The effect of posture on diaphragmatic movement and vital capacity in normal subjects with a note on spirometry as an aid in determining radiological chest volumes. Thorax. 1951;6:103-6.

Jenkins S, Soutar S, Moxham J. The effects of posture on lung volumes in normal subjects and in patient’s pre and post coronary artery surgery. Physiotherapy. 1988;74:492-6.

Leith DE. Cough Physical therapy. 1968;48:439-47.

McCool FD, Leith DE. Pathophysiology of cough. Clinics in Chest Medicine. 1987;8:189-95.

Castile R, Mead A. Effect of posture on flow-volume configuration in normal humans. J Appl Physiol. 1982;53:1175-83.

De Troyer A, Loring SH. Actions of the respiratory muscles. In RoussosC [Ed]: The Thorax [2nd Ed.] New York: Dekker, 1995; 535-563.






Original Research Articles