Contraction of the transverse abdominal muscle in pelvic girdle pain is enhanced by pain provocation during the task

Background Understanding of the pathogenesis of pain in the lumbopelvic region remains a challenge. It is suggested that lumbopelvic pain is related to decreased contraction of the transverse abdominal muscles (TrA). Objective To investigate how pain provoked by a task influences TrA contraction during that task. Design A case-control cross-sectional study. Method We recruited 40 non-pregnant women with persistent pregnancy-related posterior pelvic girdle pain (PGP) and 33 parous women (healthy controls) without PGP. TrA thickness was measured by ultrasound at various levels of bilateral hip adduction, with increments of 20 N from 0 to 140 N. Pain during the tests was registered. Results After correction for the level of adduction force, TrA thickness increase during pain-provoking tests of participants with PGP was 6.3 percentage points higher than in their pain-free tests (p = 0.01) and 0.91 percentage points higher than in the pain-free tests of healthy controls (p < 0.01). Conclusion TrA contraction in PGP is enhanced when a task provokes pain. These results may have consequences for the treatment of persistent pregnancy-related posterior pelvic girdle pain.

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