The aim of this study is to compare measurements of abdominal muscle thickness using ultrasonography imaging (USI) to those using a special transducer head device, during five different trunk stabilization exercises, ultimately to determine which exercise led to the greatest muscle thickness. Thirty eight healthy subjects participated in this cross-sectional study. The five types of trunk stabilization - i.e., a sit-up on the supine, an upper and lower extremity raise with quadruped on the prone, a leg raise in sitting on the ball, trunk rolling on the ball, and balance using sling on the prone position - were each performed with an abdominal draw. The thickness of the abdominal muscle - including the transverse abdominal (TrA), internal oblique (IO), and external oblique (EO) - was measured by USI with a special transducer head device, at rest and then at contraction in each position. Data were analyzed using one-way repeated ANOVA with the level of significance set at =.05. The results were as follows: 1) the TrA thickness was statistically significant (p<.05), whereas the IO and EO thicknesses were not (p>.05); 2) among the five types of trunk stabilization, TrA thickness significantly increased with the balance using a sling in the prone position, (p<.05), whereas no significant difference was noted for the four types of trunk stabilization (p>.05); 3) reliability data showed that there was a high degree of consistency among the measurements taken using the special transducer head device (ICC=.92). In conclusion, the balance using a sling in the prone position was more effective than any of the four other types of trunk stabilization in increasing TrA thickness in healthy subjects.

Abdominal muscle plays a crucial role in postural control and respiration control. However, thickness of abdominal muscle in the paretic side of a hemiplegic patient has not been reported in previous studies. The purpose of this research was to compare lateral abdominal muscle thickness between the nonparetic and paretic side in patients with chronic stroke using rehabilitative ultrasound imaging. Twenty two patients with chronic stroke participated in this study. Absolute thickness of transversus abdominis (TrA), internal oblique (IO) and external oblique (EO) was measured at the end of inspiration and expiration during quiet breathing, and relative thickness was calculated (thickness of each muscle as a percentage of total muscle thickness). Ultrasound imaging was recorded three times and the average value was determined for statistical analysis. Differences in absolute and relative lateral abdominal muscle thickness between the nonparetic and paretic side were assessed with paired t-tests. Absolute muscle thickness of the paretic side TrA was thinner than that of the nonparetic side at the end of inspiration and expiration during quiet breathing. Relative muscle thickness of the paretic side TrA was thinner than the paretic side only at the end of expiration during quiet breathing (p>.05). Therefore, it is necessary to strength TrA in patients with chronic stroke during physical therapy intervention. Further study is needed whether physical therapy intervension will induce TrA thickness in patients with chronic stroke in prospective study design.