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.

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The purpose of this study was to clarify the changes in lower limb muscle activities during gait caused by affixation of a heel-arch pad and timing of sole grounding (FF). [Subjects] Forty-three legs (22 male, 21 female) of 28 healthy adults. [Method] Using a foot switch, we divided the subjects into an FF-Early group and an FF-Late group, and examined and compared the groups for changes in lower limb muscle activities using surface electromyography before and after affixation of a heel-arch pad. [Results] The muscle activities of the lateral hamstrings and tibialis anterior changed significantly with FF timing. The muscle activities of the pereneous longus and medial hamstrings changed significantly when the heel-arch pad was affixed. [Conclusion] The results suggest that muscle activities are changed by the timing of FF and heel-arch pad height.

The purpose of this study was to investigate changes in the shoulder and elbow joint angles, upper limb angular velocities, and elbow varus torque when throwing balls of two different sizes. [Participants and Methods] The pitching motion of 26 junior baseball players was analyzed using an optical motion capture system. The balls used were a standard baseball and a small ball of equal weight. Shoulder external rotation/abduction and elbow flexion were measured. The maximum values of shoulder joint internal rotation, elbow joint extension, wrist flexion angular velocity, and elbow joint varus torque were also evaluated. The ball velocity was determined as an index of pitching performance. [Results] The shoulder external rotation and elbow flexion angles were higher when pitching with a small ball. The joint angular velocity was also significantly higher when pitching with a small ball for all items examined. The ball speed was significantly higher with the small ball. The maximum varus torque of the elbow joint divided by the ball velocity was significantly lower for the small ball. [Conclusion] For a junior baseball player with a small hand length, using a small ball enables pitching with low stress on the elbow joint.