Exercise Interventions for Overweight Men With Chronic Low Back Pain

Chronic non-specific low back pain (CNSLBP) is a leading cause of disability worldwide and is frequently associated with impaired pain modulation, reduced physical function, and diminished quality of life. Overweight individuals may be at increased risk of persistent low back pain due to increased mechanical loading, reduced physical fitness, and alterations in pain processing. Central sensitization has been identified as an important mechanism contributing to persistent symptoms in a subgroup of individuals with chronic low back pain.

Exercise therapy is recommended as a first-line treatment for CNSLBP; however, uncertainty remains regarding the comparative effectiveness of different exercise approaches in overweight individuals with central sensitization. Motor control exercise aims to improve the activation and coordination of deep trunk stabilizing muscles. Aerobic walking exercise may improve physical fitness and pain modulation. Muscle strengthening exercise is intended to enhance muscular strength and functional performance. Additional evidence is needed to determine which exercise strategy provides the greatest clinical benefit in this population.

This study is an assessor-blinded, four-arm, parallel-group randomized controlled trial. A total of 156 overweight male adults with non-specific chronic low back pain and evidence of central sensitization will be recruited and randomly allocated to one of four groups: motor control exercise plus patient education, aerobic walking exercise plus patient education, muscle strengthening exercise plus patient education, or patient education only. Interventions will be delivered over a 12-week period with supervised sessions conducted twice weekly.

The primary objective is to compare the effects of the interventions on conditioned pain modulation as an indicator of endogenous pain inhibitory function. Secondary objectives are to evaluate changes in pain intensity, disability, health-related quality of life, executive function, and isometric trunk muscle strength. Body weight and body mass index will also be explored as additional variables of interest.

Outcome assessments will be performed at baseline, immediately following completion of the intervention period, and at 6-month follow-up. The findings of this trial are expected to provide evidence regarding the comparative effectiveness of commonly prescribed exercise interventions for improving pain modulation and clinical outcomes in overweight men with chronic non-specific low back pain and central sensitization.

• Motor Control Exercise (Behavioral): A supervised motor control exercise program targeting deep trunk stabilizing muscles (Motor control exercises (drawing-in, multifidus, bridging, quadruped). The program focuses on improving muscle activation, coordination, and motor control during functional tasks. Sessions will be delivered twice weekly for 12 weeks under physiotherapist supervision.
• Aerobic Walking Exercise (Behavioral): A supervised moderate-intensity aerobic walking program designed to improve cardiovascular fitness and enhance endogenous pain inhibitory mechanisms. (5-min warm-up (treadmill) + 20-40 min moderate walking + 5-min cool-down + 30s stretching). Participants will perform structured walking sessions twice weekly for 12 weeks, monitored by a physiotherapist.
• Muscle Strengthening Exercise (Behavioral): A supervised progressive resistance training program targeting trunk and lower limb muscles. Exercises will focus on improving muscular strength, endurance, and functional capacity. (Rectus abdominis, obliques (OI/OE), erector spinae: curl-ups, side planks, bird dog, prone extension). The program will be delivered twice weekly for 12 weeks under physiotherapist supervision.
• Patient Education (Behavioral): A structured educational program covering chronic low back pain mechanisms, posture correction, physical activity guidance, and self-management strategies. (Health education lectures + 10-min discussion: pain neuroscience, posture, self-management) Education will be delivered throughout the 12-week intervention period.

Primary outcomes

• Conditioned Pain Modulation (CPM) [Baseline, 12 weeks, and 6 months after intervention]: Conditioned pain modulation (CPM), assessed using the Cold Pressor Test. CPM will be quantified using pressure pain threshold (PPT) measurements obtained before and after the conditioning stimulus. Higher CPM values indicate more effective endogenous pain inhibitory function.

Secondary outcomes

• Pain Intensity [Baseline, 12 weeks, and 6 months after intervention]: Change in pain intensity measured using the Numeric Pain Rating Scale (NPRS). Scores range from 0 to 10 points, with higher scores indicating greater pain intensity.
• Disability [Baseline, 12 weeks, and 6 months after intervention]: Change in disability measured using the Oswestry Disability Index (ODI). Scores range from 0 to 100 points, with higher scores indicating greater disability related to low back pain.
• Health-Related Quality of Life - Physical Domain [Baseline, 12 weeks, and 6 months after intervention]: Change in physical health-related quality of life measured using the WHOQOL-BREF Physical domain. Scores range from 0 to 100, with higher scores indicating better physical quality of life.
• Health-Related Quality of Life - Psychological Domain [Baseline, 12 weeks, and 6 months after intervention]: Change in psychological health-related quality of life measured using the WHOQOL-BREF Psychological domain. Scores range from 0 to 100, with higher scores indicating better psychological quality of life.
• Health-Related Quality of Life - Social Relationships Domain [Baseline, 12 weeks, and 6 months after intervention]: Change in social relationships measured using the WHOQOL-BREF Social Relationships domain. Scores range from 0 to 100, with higher scores indicating better social quality of life.
• Health-Related Quality of Life - Environment Domain [Baseline, 12 weeks, and 6 months after intervention]: Change in environmental quality of life measured using the WHOQOL-BREF Environment domain. Scores range from 0 to 100, with higher scores indicating better environmental quality of life.
• Working Memory [Baseline, 12 weeks, and 6 months after intervention]: Change in working memory measured using the Letter-Number Sequencing Test. The outcome will be reported as the total test score, with higher scores indicating better working memory performance.
• Executive Function [Baseline, 12 weeks, and 6 months after intervention]: Change in executive function measured using the Stroop Color-Word Test. The outcome will be reported as the Stroop interference score, with higher scores indicating poorer inhibitory control and cognitive flexibility.
• Isometric Trunk Flexion Strength [Baseline, 12 weeks, and 6 months after intervention]: Change in peak isometric trunk flexion strength measured using the DIERS myoline system. Higher peak force values indicate greater trunk flexion muscle strength.
• Isometric Trunk Extension Strength [Baseline, 12 weeks, and 6 months after intervention]: Change in peak isometric trunk extension strength measured using the DIERS myoline system. Higher peak force values indicate greater trunk extension muscle strength.
• Isometric Trunk Lateral Flexion Strength - Right [Baseline, 12 weeks, and 6 months after intervention]: Change in peak isometric right trunk lateral flexion strength measured using the DIERS myoline system. Higher peak force values indicate greater muscle strength.
• Isometric Trunk Lateral Flexion Strength - Left [Baseline, 12 weeks, and 6 months after intervention]: Change in peak isometric left trunk lateral flexion strength measured using the DIERS myoline system. Higher peak force values indicate greater muscle strength.
• Isometric Trunk Rotation Strength - Right [Baseline, 12 weeks, and 6 months after intervention]: Change in peak isometric right trunk rotation strength measured using the DIERS myoline system. Higher peak force values indicate greater muscle strength.
• Isometric Trunk Rotation Strength - Left [Baseline, 12 weeks, and 6 months after intervention]: Change in peak isometric left trunk rotation strength measured using the DIERS myoline system. Higher peak force values indicate greater muscle strength.
• Body Weight [Baseline, 12 weeks, and 6 months after intervention]: Change in body weight measured using a calibrated digital scale and reported in kilograms (kg).

Sex: Male, ages: 18 Years to 59 Years

Inclusion Criteria:

* Adults aged ≥ 18 to < 60 years.
* Diagnosed with nonspecific CLBP that has persisted for over three months.
* Overweight males (not obese), with a BMI between 25.0 and 29.9 kg/m² (the standard WHO/CDC classification). Excludes normal weight (<25 kg/m²) and obesity (≥30 kg/m²) to focus on the mechanical and metabolic consequences of excess weight and to avoid confounding by significant comorbidities, mobility restrictions, or modified exercise tolerance that may skew CPM results.
* Pain level greater than 4 on the Numerical Pain Rating Scale (NPRS).
* Signs and symptoms indicating that a CS measurement is required must be present, with a CSI score of 40 or higher.
* Psychological status will be screened with the Depression Anxiety Stress Scales-21 (DASS-21) to confirm the absence of clinically significant symptoms of depression, anxiety, or stress. Eligible participants will be overweight males aged 18 to 60 years with nonspecific CLBP who score within the normal range on all DASS-21 subscales. Participants with severe psychological distress will be excluded, while mild to moderate symptoms will be statistically controlled.

Exclusion Criteria:

* CLBP due to a recognized specific pathology (e.g., infection, tumor, osteoporosis, fracture, structural deformity, or inflammatory disorders such as ankylosing spondylitis, radiculopathy, or cauda equina syndrome).
* Contraindications for physical activity participation.
* A history of spine surgery or spine diseases that cause symptoms.
* The presence of acute pain within 48 hours prior to the study date.
* A history of using corticosteroids or other pain-affecting medications within the past two weeks is also required.
* Participants must not have other long-term pain conditions, high blood pressure, Raynaud's disease, frostbite, open wounds, broken bones, serious illnesses such as cancer, or mental health problems.
* Visual and/or hearing impairments. These criteria apply uniformly to all four study arms: MCE, AW, MSE, and the patient education (control) arm.

These specific criteria ensure that the study group is homogeneous, which is important for examining how exercise interventions affect overweight males with nonspecific CLBP who exhibit central sensitization.