Ultrasound measurement of abdominal muscles during clinical isometric endurance tests in women with and without low back pain.

PURPOSE: The present study investigated group differences between the thickness changes of the transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles, during performance of the isometric supine chest raise and the supine double leg-straight leg raise tests in women with and without low back pain (LBP). METHOD: Twenty women with LBP and 20 women without LBP participated in this case-control study. The thickness of the right TrA, IO, and EO muscles was measured using B-mode ultrasound (US) at rest, immediately at the beginning of performing the tests and when participants in both groups self-reported fatigue. The percentage of change in thickness of the abdominal muscles from rest to the initiation and fatigue stages of both tests was measured. RESULTS: The results indicate a statistically significant difference in the pattern of changes in deep (TrA) and superficial (EO) abdominal muscles thickness at the fatigue stage of the supine double straight-leg raise (SDSLR) test between groups (P < 0.05). There was no significant difference between groups for the abdominal muscles thicknesses change at rest or during stages of the clinical isometric endurance tests (P > 0.05). CONCLUSIONS: An altered activation pattern in the deep (TrA) and superficial (EO) muscles of LBP participants during fatigue stage of the SDSLR test as compared to controls indicates motor control dysfunction in the LBP group. Comparison of the activity of TrA and EO muscles during fatigue stage of SDSLR test can be used to assess alterations in motor control of abdominal muscles.

Reliability of ultrasound thickness measurement of the abdominal muscles during clinical isometric endurance tests.

The study was designed to evaluate the intra-examiner reliability of ultrasound (US) thickness measurement of abdominal muscles activity when supine lying and during two isometric endurance tests in subjects with and without Low back pain (LBP). A total of 19 women (9 with LBP, 10 without LBP) participated in the study. Within-day reliability of the US thickness measurements at supine lying and the two isometric endurance tests were assessed in all subjects. The intra-class correlation coefficient (ICC) was used to assess the relative reliability of thickness measurement. The standard error of measurement (SEM), minimal detectable change (MDC) and the coefficient of variation (CV) were used to evaluate the absolute reliability. Results indicated high ICC scores (0.73-0.99) and also small SEM and MDC scores for within-day reliability assessment. The Bland-Altman plots of agreement in US measurement of the abdominal muscles during the two isometric endurance tests demonstrated that 95% of the observations fall between the limits of agreement for test and retest measurements. Together the results indicate high intra-tester reliability for the US measurement of the thickness of abdominal muscles in all the positions tested. According to the study's findings, US imaging can be used as a reliable method for assessment of abdominal muscles activity in supine lying and the two isometric endurance tests employed, in participants with and without LBP.