Relationship between Chest Expansion and the Change in Chest Volume

[Purpose] Measurement of chest expansion is a simple and practical method for assessing patients’ respiratory function. The purpose of this study was to investigate the relationship between chest expansion and changes in chest volumes at specific locales of the thorax. [Subjects] The subjects were 12 sedentary healthy men. [Methods] Circular reflective markers were placed at points on the sternal notch, 3rd rib, xiphoid process, 8th rib, 10th rib and umbilicus. Utilizing a 3-dimensional motion analysis system, the differences in the chest volumes due to chest expansion during deep breathing were calculated. [Results] There was a highly positive correlation between chest expansion and changes in the chest volumes at all locales. [Conclusion] Being able to predict ventilatory volume per unit of chest expansion will aid in the pulmonary assessment of patients for physical therapy.