This study investigates whether the effects of core muscle strengthening exercises on chronic low back pain and deep back muscle (multifidus) thickness differ in patients with different baseline muscle thicknesses. Pain levels will be measured before and after a 6-month exercise program in patients with different baseline muscle thicknesses. The aim is to determine whether the exercises are more or less effective depending on the baseline condition of these muscles. Understanding this may help personalize exercise treatments for chronic low back pain based on individual muscle characteristics.

This prospective, randomized study will investigate if the initial thickness of deep back muscles (multifidus and erector spinae), measured via existing lumbar MRI scans, influences the effectiveness of a 6-month core stabilization exercise program for chronic low back pain. Participants aged 20-60 with chronic low back pain (over 3 months) and a recent lumbar MRI will be recruited from Çam Sakura City Hospital. Individuals with prior spinal surgery, previous physical therapy, neurological or cardiorespiratory issues, or osteoporosis will be excluded.

At baseline, muscle thickness at the L4/L5 level will be measured. Participants will receive a home-based core stabilization exercise program. Pain and function will be assessed using VAS, Oswestry Disability Index, and SPI at baseline, 3, and 6 months. The study aims to determine if patients with different baseline muscle thicknesses show varying degrees of improvement in pain and function following the exercise program. Correlation and regression analyses will explore the relationship between initial muscle thickness and changes in outcome measures. The findings may help personalize exercise treatments for chronic low back pain based on individual muscle characteristics.

Inclusion Criteria:

• Diagnosis of chronic low back pain: Participants had to have experienced low back pain for at least 3 months,
• Lumbar MRI findings without severe pathology requiring surgical intervention: Participants' lumbar MRI scans, performed at least 6 months prior to enrollment, had to show evidence of low back pain-related findings but exclude conditions necessitating surgical treatment.
• Willingness to participate in the study and provide informed consent: Participants had to voluntarily agree to take part in the research and provide their written informed consent.

Exclusion Criteria:

• History of prior spinal surgery: Individuals who had undergone any previous surgical procedures on their spine were not eligible.

Diagnosis of a neurological or rheumatological disease: Participants with pre-existing neurological conditions (e.g., radiculopathy with significant motor deficit) or rheumatological diseases (e.g., ankylosing spondylitis) were excluded.

• Cardiovascular or pulmonary comorbidities: Individuals with significant heart or lung conditions that could affect their ability to participate in the exercise program were excluded.
• Osteoporosis or osteoporotic vertebral fracture: Participants with known osteoporosis or a history of vertebral fracture due to osteoporosis were not eligible.
• Currently receiving physical therapy modalities or oral/algologic injections for low back pain: Individuals already undergoing other active treatments for their low back pain were excluded to avoid confounding the results.
• Unwillingness to participate in the study or provide informed consent: Individuals who did not want to take part in the research or were unable to provide their written informed consent were excluded.

No. While we are open to sharing individual participant data (IPD) with other researchers upon reasonable request, there is no specific platform or repository designated for making this data publicly available. Interested researchers should contact the corresponding author to inquire about data sharing, and any data transfer will be subject to ethical considerations and data sharing agreements.