Comparison of psoas major activation during standing hip flexion between chronic low back pain and healthy populations.

BACKGROUND: The psoas major (PM) has been identified as a potential contributor to chronic low back pain (LBP). However, few studies have investigated the effects of upright functional movement on PM activation in cLBP individuals. OBJECTIVE: This cross-sectional study aims to compare PM muscle activation characteristics in chronic LBP (cLBP) and healthy subjects during the transition from quiet double-leg standing to standing hip flexion. METHODS: Ultrasound Imaging was used to assess PM thickness at the lumbar vertebral level of L4-5 in 12 healthy and 12 cLBP participants. The changes in thickness between the test positions were utilized as a proxy for PM activation. RESULTS: The cLBP group exhibited greater thickness changes on the non-dominant side PM during contralateral hip flexion but not ipsilateral hip flexion (p= 0.369) compared to their healthy counterparts (p= 0.011; cLBP: resting 27.85 mm, activated 34.63 mm; healthy: resting 29.51 mm, activated 29.00 mm). There were no significant differences in dominant side PM thickness changes between the two groups during either contralateral or ipsilateral hip flexion (p= 0.306 and p= 0.077). CONCLUSION: Our findings suggest a potential overactivation of the PM in the cLBP population. This insight may aid in the development of tailored rehabilitation programs.

Comparison of transversus abdominis activation characteristics between healthy and chronic low back pain population during upright functional movement.

BACKGROUND: Previous literature suggests that transversus abdominis (TrA) activation is diminished in chronic low back pain (cLBP) subjects compared to healthy subjects in less-functional positions. However, few studies have investigated the effects of upright functional movement on TrA activation in cLBP individuals. OBJECTIVE: This pilot study aimed to compare TrA activation characteristics in healthy and cLBP subjects during the movement of double leg standing (DLS) to single leg standing (SLS) and to a 30∘ single leg quarter squat (QSLS). METHODS: TrA activation was determined by the percentage change in TrA thickness from DLS to SLS and DLS to QSLS. TrA thickness was measured in 14 healthy and 14 cLBP participants using ultrasound imaging with a probe holder at 20 mm and 30 mm from the fascia conjunction point. RESULTS: At both measurement points (20 and 30 mm), there were no significant main effects of body sides, lower limb movements and the interactions between them on TrA activations between the healthy and cLBP participants even after covariates were adjusted for (all p> 0.05). CONCLUSIONS: Results from this study suggest the evaluation of TrA activation during upright functional movements as part of an assessment for cLBP management may not be suggested.