Evaluation of the thickness of the transverse muscles of the abdomen and the internal oblique muscles using ultrasound imaging in women with back pain

Introduction: It has been estimated that chronic low back pain (LBP) affects 18% of young people, and 28-42% of people in middle age, with women being more affected than men. Chronic LBP can arise from a variety of factors, among which are biomechanical changes in core muscles, such as in their thickness, which can impair spinal stability.

Objective: To analyze the thickness of the transversus abdominis (TrA) and internal oblique (IO) and muscles on the right side in different postures.

Methods: Sedentary women with a normal Body Mass Index were recruited. Participants with a history of chronic LBP comprised the LBP Group, and individuals without LBP, the control group. The young women underwent analysis of the thickness of the abdominal muscles using ultrasound imaging. ANOVA was used to compare changes in muscle thickness in the three positions.

Results: There was no significant difference between the groups in the supine and sitting position for the TrA and IO muscles. In the sitting position with the left lower limb raised, a significant difference was observed for TrA (p = 0.0013) among groups.

Conclusions: The LBP group showed a decrease in the TrA thickness in the sitting position with the lower limb raised, when compared to the control group, indicating failure in muscle activation in this group. These findings suggest that as stability decreases, TrA thickness increases in women without LBP. Finally, in women who report having LBP, TrA recruitment is not efficient for unstable postures.