Effects of the Iliopsoas Strain–Counterstrain Technique on Mechanical Chronic Low Back Pain: A Randomized Controlled Trial

Background Mechanical chronic low back pain (MCLBP) often involves dysfunction in soft tissues, particularly in the iliopsoas muscle, which is crucial for lumbar stability and movement. This study aimed to evaluate the effects of the strain-counterstrain (SCS) technique applied to iliopsoas tender points (TPs) on pain reduction and lumbar mobility in individuals with MCLBP. Methods Between January and March 2025, this unmasked randomized controlled trial (RCT) Between January and March 2025 enrolled 36 volunteers aged 18–60 years with MCLBP and iliopsoas tenderness. Thereafter, they were randomly allocated (1:1) to either a control group (exercise only, 6 sessions) or SCS group (exercise + iliopsoas-targeted SCS, 6 sessions). The primary outcomes were pain at rest and during flexion, as measured by the visual analog scale (VAS). The secondary outcomes included lumbar flexion and extension range of motion (ROM), spinal mobility, iliopsoas muscle length, Oswestry Disability Index (ODI), and Short Form-36 (SF-36) score. Assessments were performed at baseline, after the first session, and after the sixth session. Results Thirty-six participants were randomly assigned to the SCS group (n = 18) or the control group (n = 18). Compared with those in the control group, the pain levels in the SCS group were significantly lower, with a between-group mean difference (MD) of -1.8 cm (95% CI: -2.98, 0.62) at rest and − 2.67 cm (95% CI: -3.97, -1.37) during lumbar flexion. After the sixth session, further reductions in pain at rest (MD -1.87 [95% CI -3.2, -0.54]) and during flexion (MD -3.32 [95% CI -5.17, -1.46]) were observed in the SCS group. Lumbar ROM improved significantly with increased flexion (MD 14.78 [95% CI 5.35, 24.25]) and extension (MD 8.17 [95% CI 2.57, 13.77]) after the sixth session. Spinal mobility, ODI scores, and SF-36 physical functioning scores improved after both sessions. No adverse events were reported. Conclusion The iliopsoas-targeted SCS technique combined with therapeutic exercises effectively reduced pain and improved lumbar mobility in patients with MCLBP, with notable improvements observed after the first and sixth sessions. Trial Registration The trial was prospectively registered at ClinicalTrials.gov (NCT06748859) on December 13, 2024. Available from: https://clinicaltrials.gov/ct2/show/NCT06748859.