A three-dimensional image analysis device was used to measure thoracic shape in the horizontal plane to investigate how left/right asymmetry affects thoracic mobility and respiratory function. [Subjects and Methods] The subjects were 20 healthy adult men. A three-dimensional image analysis device was used to create horizontal, cross-sectional views of the upper and lower thorax expiratory levels. The left and right cross-sectional areas were compared. Relationships between left/right ratios of thoracic shape and mobility and respiratory function were investigated. [Results] Comparisons of left/right thorax cross-sectional area ratios revealed left/right asymmetry, with larger left upper and right lower thoraces. Correlations were found between left/right thoracic cross-sectional area ratios, rates of chest expansion, and respiratory function. [Conclusion] Resting expiratory-level thoracic shapes showed left/right asymmetry, with larger left upper and right lower thoraces. The extent of left/right asymmetry in thoracic shape may affect functional activity during respiration and may be reflected in thoracic mobility and respiratory function.

The purpose of this study was to investigate the relations of bilateral symmetry in the cross-sectional area of quadratus lumborum muscles with frontal posture and respiratory function. [Subjects and Methods] The subjects were 20 healthy males. Measurement items comprised the cross-sectional area of the quadratus lumborum muscles, frontal posture, thoracic extension rate, respiratory muscle strength, and pulmonary function. [Results] Bilateral asymmetry was observed in the cross-sectional area of quadratus lumborum muscles; the mass of the right quadratus lumborum muscle was larger than that of the left quadratus lumborum muscle. Significant positive correlations were found between bilateral symmetry of the cross-sectional area of the quadratus lumborum muscles and frontal posture, thoracic extension rate, and expiratory muscle strength; and there was a significant negative correlation with the pulmonary function index of residual volume. [Conclusion] The present study revealed relationships between bilateral symmetry in the cross-sectional area of the quadratus lumborum muscles and frontal posture and respiratory function.

[Purpose] We analyzed the relationship between the degree of asymmetry in the shape of the thorax and postural changes in the frontal plane, and examined the mechanism that creates an asymmetry in the thoracic shape. [Participants and Methods] The participants included 19 healthy young males. We calculated the thoracic volume and lateral deviation from the amount of displacement of reflective markers attached to the thoracic area using the Vicon MX 3D-analysis system. [Results] Left-right differences were shown in each area of the thorax, and positive and negative correlations were found with the amount of lateral deviation of the thorax, which captured postural changes in the frontal plane. [Conclusion] The results of this study suggest that postural changes in the frontal plane are factors involved in the mechanism of left-right asymmetry formation in the thoracic shape.

[Purpose] This study aimed to introduce an approach of pelvic suspension (PS) using sling cords and to obtain evidence for changes in respiratory function of healthy subjects. [Subjects and Methods] Subjects were 25 healthy men. In the supine position, with hip and knee joints flexed at 90°, the subjects’ pelvises were suspended with sling belts. Diaphragm excursion, respiratory function, and respiratory comfort in these postures were measured using ultrasonography, respirometry, and visual analog scale (VAS), respectively. [Results] When the pelvis was passively suspended with sling cords, the diaphragm moved 5 mm cranially and diaphragm excursion showed an instantaneous increase compared with the control. The tidal volume (VT) showed an increase and the respiration rate (RR) showed a decrease. The extent of diaphragm excursion was correlated with changes in VT under the control and PS conditions. Independent measurements of pulmonary function revealed that PS reduced the expiratory reserve volume, being correlated positively and negatively to increases in vital and inspiratory capacities, respectively. Furthermore, VAS values for respiratory ease were greater with PS than with the control. [Conclusion] These results suggest that PS effectively changed diaphragm excursion and respiratory function, leading to ease of breathing (i.e., deep and slow respiration).

Purpose] The purpose of this study was to investigate the presence of asymmetry in the thickness of the latissimus dorsi muscles (LD) and the relations of the asymmetry to pelvic lateral tilt angle and respiratory function during forced expiration. [Participants and Methods] The subjects were 20 healthy males. Measurement items were the thicknesses of the bilateral LDs, pelvic lateral tilt angle and respiratory function.[Results] During resting expiration, the right LD was significantly thicker than the left LD. There was a correlation between the lateral asymmetry of the thicknesses of the LD and %IC. During forced expiration, the thickness of the left LD increased. The asymmetry in the thickness of the LD correlated with the pelvic lateral tilt angle during forced expiration and with %PE max. [Conclusion] These results suggest that asymmetry in the thickness of the LD is involved in %IC, %PE max, and pelvic stabilization in the frontal plane.