Document Type : Research articles


1 Physiotherapy Research Center, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran

2 Proteomics Research Center, Department of Biostatistics, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran

3 English Language Department, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran


Background: Various studies have reported that the pelvic girdle and lumbar spine are reflexively stabilized and braced prior to the initiation of extremity movements.
Objectives: The present study aimed to assess the reliability of the diaphragm muscle thickness and excursion measured by reha- bilitative ultrasound imaging (RUSI).
Methods: This is a cross-sectional study that was done in the physiotherapy department of the Faculty of Rehabilitation at the Shahid Beheshti University of Medical Sciences (Tehran, Iran) in 2019. Images of diaphragm thickness were taken using RUSI in the
intercostal space between the 7th and 8th, or 8th and 9th ribs, at which the diaphragm was more easily visualized. The diaphragm
motion assessment was performed by applying the transducer on the abdomen at the right midclavicular line. Imaging was con-
ducted in 10 participants with pelvic girdle pain (PGP) and 10 asymptomatic women and men aged 20 - 44 years. Images were ob-
tained by one examiner, muscle thickness was measured using B mode RUSI, and the motion was assessed using M mode RUSI. All
assessments were performed in quiet breathing and deep breathing states. Intraclass correlation coefficients (ICC), standard error
of measurement (SEM), and minimal detectable change (MDC) were used for reliability assessment.
Results: The ICC, SEM, and MDC values revealed an excellent intrarater reliability for RUSI in both groups to measure the diaphragm
thickness (ICC between 0.88 to 0.92). Measurement of diaphragm excursion demonstrated excellent reliability in the asymptomatic
group (ICC between 0.80 to 0.90) and less reliability, between good and excellent, in the PGP group (ICC between 0.74 to 0.79).
Conclusions: The method of RUSI employed in the present study is recommended for measuring diaphragm thickness and motion
in patients with PGP.