Chronic low back pain (CLBP) is a prevalent disfunction in the spine, affecting both women and men. The implication of the abdominal muscles in this disfunction has been studied, including wrong breathing patterns or inactivity of this area. However, there is a lack of studies examining changes in thickness of abdominal with ultrasonography. Thus, the aim of this study is to analyze the differences in the thickness of abdominal muscles at rest and during breathing between subjects with and without CLBP. A total of 72 subjects were divided in two groups: participants with CLBP (n = 36) and participants without CLBP (n = 36). In both groups, the thickness of the four abdominal muscles was measured and compared at rest and during breathing with ultrasonography. In TrA and IO there were no significant differences between groups, but those subjects with CLBP increased the muscle thickness more than participants without pain during breathing. In EO there were no differences in muscle thickness between groups and between rest and breathing. In RA, subjects with CLBP showed less muscle thickness than subjects without pain during breathing, but no changes were found at rest. In conclusion, the deepest abdominal muscles, TrA and IO, appear to increase their thickness and RA appear to decrease more in subjects with CLBP, in comparison with healthy participants.
Keywords: abdominal muscles; low back pain; physiotherapy; ultrasonography.