The goal of this randomized controlled trial is to determine the effect of a psoas major muscle intervention on non-specific and chronic lumbar pain in cleaning professionals. It is expected that this intervention will reduce the severity and frequency of symptoms. This study aims to evaluate the effect of psoas major stretching techniques. To collect data, participants will rate their pain intensity on a numeric pain scale at rest and during maximal lumbar flexion. Secondary variables include lumbar flexion range of motion (ROM), assessed by the Schöber test, and hip ROM, which will be measured before and after the intervention using a digital goniometer.

Cleaning professionals are particularly vulnerable to musculoskeletal pain, predominantly low back pain due to intense occupational hazards like repetitive movements, heavy lifting in awkward postures, and prolonged standing. The psoas major muscle plays a critical role in this clinical context; morphological changes, such as muscle atrophy and fat infiltration, are commonly observed in low back pain patients. Furthermore, a shortened or asymmetrical psoas alters spinal biomechanics-often increasing lumbar lordosis and overloading facet joints-which strongly predisposes individuals to chronic pain and instability. Furthermore, a shortened or asymmetrical psoas alters spinal biomechanics-often increasing lumbar lordosis and overloading facet joints-which strongly predisposes individuals to chronic pain and instability.

This study aims to highlight the biomechanical importance of the iliopsoas muscle and evaluate the therapeutic impact of the stretching technique in reducing symptoms, improving mobility, and preventing functional limitations associated with iliopsoas dysfunction.

Inclusion Criteria:

• Being a cleaning professional for at least 4 years
• Report at least 1 episode of lumbar pain in the last 3 months

Exclusion Criteria:

• Any severe spinal condition (such as spondylolisthesis, spine fracture, etc.)
• Any severe neurological or rheumatological condition
• Pregnancy
• Daily use of pain medication

All evaluations will be conducted by an independent, blinded assessor who is not involved in administering the interventions. First, participants will complete a screening questionnaire to confirm they meet all inclusion and exclusion criteria. Baseline measurements will then be recorded, including pain intensity at rest and during maximal lumbar flexion, as well as lumbar mobility via the Schöber test. Following the initial assessment, the blinded assessor will leave the room, and a separate investigator will administer the assigned intervention. Afterward, the blinded assessor will return to conduct the post-intervention assessment using the same protocols. Participants will be blinded to their group allocation, ensuring a participant- and assessor-blinded study design.