The purpose of this study is to assess the morphological changes in the lumbar multifidus, Erector spinae and Quadratus lumborum muscles and to investigate whether they are correlated with trunk extensor muscle strength in CNSLBP subjects.

and to compare between these morphological changes during rest and contraction and to compare these results with control group.

Twenty-nine subjects with CNSLBP and 29 age-matched healthy controls will be assessed by ultrasonography to detect the morphological changes of these muscles during rest and contraction ,and assessed strength of back extensors by hand-held dynamometer, and assessed functional disability by Arabic version of Oswestry disability index . They will be asked to sign the informed consent form.

Low back pain (LBP) is one of the most common musculoskeletal disorders leading to inactivity, postural disorders, and muscle problems and can result in disability, reduced quality of life, and workforce loss.

Low back pain is commonly classified as non-specific (90%) or specific (10%) according to reported cause and as acute (<6 weeks), subacute (6-12 weeks) or chronic (more than12 weeks) according to duration of symptoms.

Many factors have been reported to play a role in the etiology of Chronic non-specific Low back pain (CNSLBP) including occupational factors, personal factors, and behavioral risk factors. In addition, recent studies associate low back pain with physical factors such as lumbar spinal stiffness, muscle shortness, and decreased endurance and muscle strength.

Many studies have mainly focused on the morphological aspects of paraspinal muscles including lumbar multifidus , Erector spinae and Quadratus lumborum muscles, which play an essential role in patients with CNSLBP in terms of functional disability and the planning of rehabilitation modalities.

Twenty-nine subjects with CNSLBP and 29 age-matched healthy controls will be recruited through direct referral. They will be asked to sign the informed consent form.

To authors knowledge no previous research had investigated the correlation between morphological changes and strength of back muscles in subjects with CNSLBP

The finding of this proposed work may help researchers interested in CNSLBP's etiology and natural course which can be considered a topic that are still poorly understood. To reduce the occurrence and severity of CNSLBP, it is essential to help understand its cause and determine whether there are any risk factors that may be changed.

The finding of this proposed work may benefit patients diagnosed with CNSLBP. If the diagnosis of back pain, function, and muscle strength in those patients become more clear , not only this may make them return to work early but may also improve psychological status.

Inclusion Criteria:

1. Subjects of both genders with CNSLBP (pain> 3 months)
2. The subject's age ranged between 18 and 45.
3. waist-to-height ratio (WHtR) < 0.5 or = 0.5

Exclusion Criteria:

1. Untreated neurological and/or mental illness
2. History of trauma in the last 6 months.
3. Sacroiliac joint pathologies.
4. Spinal fracture or dislocation.
5. Spinal instability (e.g., spondylolisthesis or retrolisthesis)
6. Sensitivity to ultrasound gel diagnosed by a medical doctor.
7. Serious musculoskeletal problems or other pathologies.
8. Previous surgery in lower limb(s)
9. Females during Pregnancy.

Outpatient clinic of Mallawi Hospital

undecided