Relationship between postural control and respiratory movement during one-leg standing in healthy males.

[Purpose] The purpose of this study was to examine the relationship between postural control and respiratory movements after identifying the characteristics of respiratory movements in different postural holding tasks. [Participants and Methods] The total trajectory length was measured using a stabilometer (G-620; Anima Company, Tokyo, Japan), while respiratory movements were measured using an expiratory gas analyzer (PowerMetz; Anima Company, Tokyo, Japan) during closed-leg and one-leg standing. Respiratory movements were characterized as tidal volume (TV), respiratory rate (RR), minute volume (MV), and metabolic equivalents (METs). [Results] The total trajectory length, METs, RR, and MV were higher in one-leg standing than in closed-leg standing. The rate of change in the total trajectory length during one-leg standing was positively correlated with the rate of change in TV and negatively correlated with RR. [Conclusion] The results suggest that postural control of one-leg stance holding is associated with changes in respiratory motion.

Analysis of the asymmetry of thoracic shape at rest: relationship with lateral thoracic deviation.

[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.

Effects of the posterior pelvic tilt sitting posture on thoracic morphology and respiratory function.

[Purpose] We investigated how differences in pelvic angle in the posterior pelvic tilt sitting posture simultaneously affect the thoracic morphology and the respiratory function. [Participants and Methods] The participants were 18 healthy young males. We positioned the pelvis at 0°, 10°, 20°, and 30° of posterior tilt, following which the thoracic expansion volume ratio, thoracic spine tilt angle, and respiratory function were measured. We calculated the thoracic volume and thoracic spine tilt angle by measuring the amount of displacement of reflective markers attached to the thoracic area using the Vicon MX 3D-analysis system. Respiratory function was measured by spirometry. [Results] The expansion volume ratio decreased significantly in response to 10-30° posterior pelvic tilt sitting at the mid-thorax and 30° posterior pelvic tilt sitting at the lowest thorax. The upper thoracic spine level showed a change in anterior tilt at 10-30° posterior pelvic tilt sitting, whereas the lower thoracic spine level showed a change in posterior tilt at 30° posterior pelvic tilt sitting. Respiratory function was significantly lower at 30° posterior pelvic tilt sitting than at 0° posterior pelvic tilt sitting. A positive correlation between thoracic expansion volume ratio and respiratory function was found at 30° posterior pelvic tilt sitting. [Conclusion] Changes in thoracic spine tilt angle due to posterior pelvic tilt sitting may restrict the expansion of thoracic motion during respiration, thereby affecting respiratory function.