Abstract
[Purpose] The purpose of this study was to investigate the function of respiratory muscles during breathing exercises by ultrasonography, and to determine if marked recruitment of respiratory muscles could be distinguished by this technique. [Methods] Thirteen healthy male subjects were asked to perform two breathing exercises in random order: diaphragmatic breathing (DB), and pursed-lip breathing (PLB). Changes in diaphragm thickness (ΔTdi) and lateral abdominal muscle thickness (ΔTlab) were measured by B mode ultrasonography. Tidal volume (TV) and respiratory rate (RR) were measured by spirometry. [Results] Compared to quiet breathing (QB), TV and ΔTdi significantly increased, whereas RR significantly decreased during the two breathing exercises. ΔTlab also significantly increased during DB, but not significantly during PLB, when compared to QB. ΔTlab during QB and DB was significantly correlated with TV. No significant difference was found, however, between the two breathing exercises in terms of TV, RR, ΔTdi, and ΔTlab. [Conclusion] Although changes in TV, RR, and ΔTdi during the two breathing exercises were comparable, the change in ΔTlab was different. Ultrasonography of respiratory muscles is a simple technique that may prove useful in the assessment of the pattern of respiratory muscle recruitment.
