Background and purpose:  Previous studies have investigated the correlation between activity of superficial trunk muscle and postural control in patients with low back pain (LBP), but the relationship between deep trunk muscle activity, as spinal stabilizer, and postural control during standing postural tasks is not clear yet. This study investigated the relationship between abdominal muscle activity
(deep and superficial) and postural control during standing postural tasks in females with chronic nonspecific LBP.

Materials and methods: In an analysis of relationships, 44 females were asked to maintain their balance during standing on the platform stability levels of Biodex Balance System (BBS) (static, levels 6 and 3) for 30 seconds and BBS data were saved. Concurrently, ultrasonography (US) data for abdominal muscles thickness measurement were recorded. Then, saved data were processed offline using Corel DRAW software.

Results: Significant correlations were found between transversus abdominis (TrA), and external oblique (EO) muscle thickness changes and postural stability indices in all testing conditions (P<0.05), however, the correlation was not strong.

Conclusion: Dysfunction in superficial and deep abdominal muscles activity pattern affects postural control changes in the patients with LBP. This relationship signifies the role of stabilization motor control training, especially deep abdominal muscle training, on postural control improvement in patients with LBP.