Abstract
[Purpose] Some patients with respiratory disease exhibit asymmetrical movement of the thorax. The purpose of this study was to investigate the relationship of thoracic configuration with changes in thoracic volume in 13 sedentary healthy men. [Subjects and Methods] In upright sitting, 84 reflective markers were placed on the anterior and posterior aspects of the trunk to record thoracic volume during quiet and volitional deep breathing. Using a three-dimensional motion analyzer, the difference in volume within the upper and lower hemithoraces was measured. For calculation of the thoracic volume six imaginary hexahedra were visualized for the upper and lower thorax using four reflective markers for each on the anterior and posterior aspects of the thorax. Each hexahedron was then divided into three imaginary triangular pyramids to calculate positional vectors. Finally, the volume for both the hexahedra and triangular pyramids was calculated. Four thoracic volumes were obtained. [Results] The findings showed that the left upper and right lower hemithorax yielded significantly larger thoracic volumes. [Conclusion] In conclusion the left upper and right lower hemithoraces were found to expand more than their corresponding sides. Understanding the characteristics of thoracic excursion during quiet and volitional deep breathing could be of value in assessment and instruction of breathing techniques to patients.