Effects of Measurement Posture on Pulmonary Function Test(PFT) Outcomes in Healthy Adult Males

Purpose: This study aimed to determine whether forced vital capacity, forced expiratory volume in 1 s, forced expiratory volume in 1 s/forced vital capacity, maximum expiratory flow rate, and maximum inspiratory/expiratory pressure vary according to the test posture. Methods: For this purpose, 30 healthy university students in their 20s were assessed in the supine position, 45° sitting position, and 90° sitting position for forced vital capacity, forced expiratory volume in 1 s, forced expiratory volume in 1 s/forced lung capacity, peak expiratory flow, maximum inspiratory/expiratory pressure, and the results were statistically analyzed using one-way analysis of variance and Bonferroni post-hoc test. Results: A significant difference was found between the supine position, forced lung capacity, and forced expiratory volume in 1 s in 90° sitting position (p<.05); however, no significant difference was found between forced expiratory volume/forced vital capacity, peak expiratory flow, and maximal inspiratory/expiratory pressure in 1 s (p>.05). Conclusion: The results showed that assessment in the supine or 45° sitting position rather than in the 90° sitting position affects breathing but not respiratory muscle strength.