• Naitoh S
• Tomita K
• Sakai K
• Yamasaki A
• Kawasaki Y
• Shimizu E

• Lung / physiology
• Movement / physiology
• Posture / physiology
• Respiratory Function Tests
• Thoracic Wall / physiology

Objective: The purpose of this study was to investigate the effect of different recumbent positions on pulmonary function, chest wall motion, and feelings of discomfort in young nonobese healthy volunteers.

Methods: Twenty healthy volunteers (age, 28.0 ± 1.4 years; height, 167.5 ± 10.1 cm; weight, 62.3 ± 10.2 kg) were studied in the sitting position and in the following 6 recumbent positions: supine, left retroversion at a 45° tilt, left anteversion at a 45° tilt, right retroversion at a 45° tilt, right anteversion at a 45° tilt, and prone. After 5 minutes of a selected position, pulmonary functions, including vital capacity (VC), forced expiratory volume in 1 second, maximal inspiratory and expiratory mouth pressures (MIP and MEP, respectively), and breathing pattern components at the chest wall were assessed. Discomfort was assessed using a modified Borg scale.

Results: When participants changed position from sitting to each of the 6 recumbent positions, forced expiratory volume in 1 second values decreased significantly (P < .05). None of the participants showed changes in the MIP or MEP in any of the 6 recumbent positions. Rib cage motion was restricted in all recumbent positions except supine, left anteversion at a 45° tilt, and prone. In all 6 recumbent positions, discomfort was experienced during the pulmonary tests. However, in the left retroversion at a 45° tilt position, no discomfort was experienced during the MIP and MEP assessments.

Conclusion: In young, nonobese, healthy volunteers, recumbent positions caused diminished pulmonary functions and induced feelings of discomfort.

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