Abstract
[Purpose] This study investigated the reliability of measuring the muscle thicknesses of the external oblique (EO), internal oblique (IO) and transversus abdominis (TrA) by B-mode ultrasound in the neutral position and with 50% trunk rotation, in sitting. [Subjects] The subjects were 21 healthy young men. [Method] Muscle thicknesses were measured three times, at rest, with rising abdominal muscle pressure, and with added resistance, in the two positions. The coefficient of reliability of each condition was calculated from the measured values. When we found a low coefficient of reliability, we determined the the number of measurements that would guarantee high reliability. [Result] The coefficient of reliability of measuring the muscle thicknesses of EO and IO was better than 0.70, but that of TrA was 0.46. To achieve a coefficient of reliability of 0.70, 2.7 measurements are required. [Conclusion] In order to guarantee a high coefficient of reliability when measuring abdominal muscle thicknesses, it is necessary to use the average value of three measurements.
