Body position influences the maximum inspiratory and expiratory mouth pressures of young healthy subjects

Abstract

ObjectiveThe purpose of this study was to determine the effects of body position on respiratory muscle strength of young healthy subjects. ParticipantsSixty-three (50 female, mean age 19.7±1.5 years) healthy subjects participated in the study. DesignParticipants were measured in the sitting position, semi-upright sitting position, and in the supine position. The order of the three conditions was randomly determined. Outcome MeasuresMaximal inspiratory and expiratory mouth pressures (PImax, PEmax) and lung function. ResultsA significant effect of body position was observed on PEmax values, controlling for gender. PImax in the sitting position (92.8±20.05cm H2O) was significantly higher than in the supine (84.1±15.1cm H2O; mean difference: 8.70, 95% CI [5.95, 12.45], p<0.001) and semi-upright sitting positions (84.4±17.5cm H2O; mean difference: 8.43, 95% CI [5.78, 11.07], p<0.001). PEmax was also significantly higher in the sitting position (125.4±34.2cm H2O) than in the supine (115.8±29.0cm H2O; mean difference: 9.59, 95% CI [4.86, 14.32], p<0.001) and semi-upright sitting positions (120.2±33.9cm H2O; mean difference: 5.21, 95% CI [0.87, 9.54], p=0.013). ConclusionsBody position influences respiratory muscle strength of young healthy subjects. PImax and PEmax are higher in the sitting position than in the supine or semi-upright sitting positions.