The Forgotten Role of Back Muscle Characteristics to Tailor Exercise Therapy for Recurrent Non-specific Low Back Pain

Study Overview
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Brief Summary
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Patients with non-specific low back pain will be compared to healthy, age- and sex-matched controls to determine the most discriminating back muscle characteristics and to delineate possible phenotypes of patients with non-specific low back pain showing impaired proprioceptive postural control. Additionally, the group of patients with non-specific low back pain will receive a 16-week, high-load proprioceptive training program. The effects of this training program on the different back muscle characteristics and proprioceptive postural control will be evaluated.

Detailed Description
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The Back-to-Back study consists of a cross-sectional study and a proof-of-concept study. The cross-sectional study aims to gain more insight into the peripheral underlying mechanisms of impaired proprioceptive postural control in patients with non-specific low back pain. Macroscopic, microscopic, hemodynamic, and electrophysiological characteristics of the lumbar multifidus and erector spinae muscles will be compared between patients with non-specific low back pain and healthy, age- and sex-matched controls. The interrelatedness between these back muscle characteristics and the correlation with proprioceptive postural control will be examined. The most discriminating muscle characteristics will be determined based upon which phenotypes of patients with non-specific low back pain will be delineated. The proof-of-concept study aims to assess the effects of high-load proprioceptive training on back muscle characteristics and proprioceptive postural control in patients with non-specific low back pain.

Official Title
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Back to Back: the Forgotten Role of Back Muscle Characteristics to Tailor Exercise Therapy for Recurrent Non-specific Low Back Pain

Conditions
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Low Back Pain, Back Pain Lower Back Chronic

Intervention / Treatment
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* Other: Proprioceptive training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with non-specific low back pain: Aged 18-60 years Non-specific low back pain without radicular leg pain Mechanical low back pain with episodes of <4 on the numerical pain rating scale and episodes of >6 on the numerical pain rating scale Non-specific low back pain for three months or more Score of 20% or more on the Modified Low Back Pain Disability Questionnaire Informed consent to participate Healthy controls: Aged 18-60 years No history of low back pain needing medical treatment or resulting in a limited activity level No low back pain in the previous six months Informed consent to participate Exclusion Criteria: Pregnancy Previous trauma or surgery to the spine, pelvis or lower limbs Structural spinal deformity (e.g., scoliosis) Neurological, neuromuscular, respiratory or systemic disease Central sensitization: score of 50/100 or more on the Central Sensitization Inventory Specific vestibular or balance problems Acute lower limb or neck problems Body mass index of 30 kg/m² or more

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Patients with non-specific low back pain<br>Individuals with chronic non-specific ow back pain | Other: Proprioceptive training<br>* A physiotherapist tailors the exercises to the patient's functional demands and pain- or fear-inducing activities. Guided by the therapist, patients look for ways to integrate the exercises into their daily life activities. Each week, patients receive feedback from the physiotherapist, and the training program is gradually progressed. The patients are instructed to perform the exercises daily, integrated into their daily activities, hobbies, and work. The program contains: (1) exercises to improve the sense of posture and movement, (2) exercises to correct the reference frame from which patients control posture and movement, (3) muscle control exercises, (4) exercises to increase variability in postures and movement patterns, (5) functionality: patients search for ways to correct and integrate alternative postures and movement patterns into their daily life, (6) high training frequency and high load, (7) focus on sensing, localizing and differentiating, rather than movement control.<br>|
| Healthy controls<br>Healthy, age- and sex-matched individuals without low back pain | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proprioceptive postural control at baseline 1 (t= 0 weeks) | Center-of-pressure displacement in response to ankle and/or back muscle vibration and the Relative Proprioceptive Weighting ratio will be calculated. | At baseline 1 (t= 0 weeks) | 
| Proprioceptive postural control at baseline 2 (t= 8 weeks) (only for patients) | Center-of-pressure displacement in response to ankle and/or back muscle vibration and the Relative Proprioceptive Weighting ratio will be calculated. | At baseline 2 (t= 8 weeks) | 
| Proprioceptive postural control after 8 weeks of training (t= 16 weeks) (only for patients) | Center-of-pressure displacement in response to ankle and/or back muscle vibration and the Relative Proprioceptive Weighting ratio will be calculated. | After 8 weeks of training (t= 16 weeks) | 
| Proprioceptive postural control after 16 weeks of training (t= 24 weeks) (only for patients) | Center-of-pressure displacement in response to ankle and/or back muscle vibration and the Relative Proprioceptive Weighting ratio will be calculated. | After 16 weeks of training (t= 24 weeks) | 
| Proprioceptive postural control 16 weeks after the end of training (t= 40 weeks) (only for patients) | Center-of-pressure displacement in response to ankle and/or back muscle vibration and the Relative Proprioceptive Weighting ratio will be calculated. | 16 weeks after the end of training (t= 40 weeks) | 
| Macroscopic characteristiscs of the lumbar multifidus and erector spinae muscles at t= 0 weeks (only for healthy controls) | Muscle volume and quality will be measured with 3D freehand ultrasound, muscle cross-sectional area and thickness will be evaluated with 2D ultrasound. | At t= 0 weeks | 
| Macroscopic characteristiscs of the lumbar multifidus and erector spinae muscles at baseline 2 (t= 8 weeks) (only for patients) | Muscle volume and quality will be measured with 3D freehand ultrasound, muscle cross-sectional area and thickness will be evaluated with 2D ultrasound. | At baseline 2 (t= 8w, 2nd baseline) | 
| Macroscopic characteristics of the lumbar multifidus and erector spinae muscles after 16 weeks of training (t= 24 weeks) (only for patients) | Muscle volume and quality will be measured with 3D freehand ultrasound, muscle cross-sectional area and thickness will be evaluated with 2D ultrasound. | After 16 weeks of training (t= 24 weeks) | 
| Macroscopic characteristisc of the lumbar multifidus and erector spinae muscles 16 weeks after the end of training (t= 40 weeks) (only for patients) | Muscle volume and quality will be measured with 3D freehand ultrasound, muscle cross-sectional area and thickness will be evaluated with 2D ultrasound. | 16 weeks after the end of training (t= 40 weeks) | 
| Microscopic muscle characteristics of the lumbar multifidus and erector spinae muscles at t= 0 weeks (only for healthy controls) | Fine-needle biopsies of the lumbar multifidus and erector spinae muscles will be acquired. | At t= 0 weeks | 
| Microscopic muscle characteristics of the lumbar multifidus and erector spinae muscles at baseline 2 (t= 8 weeks) (only for patients) | Fine-needle biopsies of the lumbar multifidus and erector spinae muscles will be acquired. | At baseline 2 (t= 8 weeks) | 
| Microscopic muscle characteristics of the lumbar multifidus and erector spinae muscles after 16 weeks of training (t= 24 weeks) (only for patients) | Fine-needle biopsies of the lumbar multifidus and erector spinae muscles will be acquired. | After 16 weeks of training (t= 24 weeks) | 
| Microscopic muscle characteristics of the lumbar multifidus and erector spinae muscles 16 weeks after the end of training (t= 40 weeks) (only for patients) | Fine-needle biopsies of the lumbar multifidus and erector spinae muscles will be acquired. | 16 weeks after the end of training (t= 40 weeks) | 
| Hemodynamic muscle characteristics of the lumbar multifidus and erector spinae muscles at baseline 1 (t= 0 weeks) | The Tissue Oxygenation Index will be recorded continuously with near-infrared spectroscopy during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | At baseline 1 (t= 0 weeks) | 
| Hemodynamic muscle characteristics of the lumbar multifidus and erector spinae muscles at baseline 2 (t= 8 weeks) (only for patients) | The Tissue Oxygenation Index will be recorded continuously with near-infrared spectroscopy during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | At baseline 2 (t= 8 weeks) | 
| Hemodynamic muscle characteristics of the lumbar multifidus and erector spinae muscles after 8 weeks of training (t= 16 weeks) (only for patients) | The Tissue Oxygenation Index will be recorded continuously with near-infrared spectroscopy during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | After 8 weeks of training (t= 16 weeks) | 
| Hemodynamic muscle characteristics of the lumbar multifidus and erector spinae muscles after 16 weeks of training (t= 24 weeks) (only for patients) | The Tissue Oxygenation Index will be recorded continuously with near-infrared spectroscopy during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | After 16 weeks of training (t= 24 weeks) | 
| Hemodynamic muscle characteristics of the lumbar multifidus and erector spinae muscles 16 weeks after the end of training (t= 40 weeks) (only for patients) | The Tissue Oxygenation Index will be recorded continuously with near-infrared spectroscopy during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | 16 weeks after the end of training (t= 40 weeks) | 
| Electrophysiological muscle characteristics of the lumbar multifidus and erector spinae at baseline 1 (t= 0 weeks) | Muscle activitation levels and patterns will be measured with surface electromyography during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | At baseline 1 (t= 0 weeks) | 
| Electrophysiological muscle characteristics of the lumbar multifidus and erector spinae at baseline 2 (t= 8 weeks) (only for patients) | Muscle activitation levels and patterns will be measured with surface electromyography during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | At baseline 2 (t= 8 weeks) | 
| Electrophysiological muscle characteristics of the lumbar multifidus and erector spinae after 8 weeks of training (t= 16 weeks) (only for patients) | Muscle activitation levels and patterns will be measured with surface electromyography during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | After 8 weeks of training (t= 16 weeks) | 
| Electrophysiological muscle characteristics of the lumbar multifidus and erector spinae after 16 weeks of training (t= 24 weeks) (only for patients) | Muscle activitation levels and patterns will be measured with surface electromyography during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | After 16 weeks of training (t= 24 weeks) | 
| Electrophysiological muscle characteristics of the lumbar multifidus and erector spinae 16 weeks after the end of training (t= 40 weeks) (only for patients) | Muscle activitation levels and patterns will be measured with surface electromyography during different functional postures (prone lying, usual sitting, usual standing, standing with the trunk bent 25° forward). | 16 weeks after the end of training (t= 40 weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Disability due to low back pain | Participants will be asked to complete the Modified Low Back Pain Disability Questionnaire. | Controls: once, immediately after inclusion, Patients: 5 times, immediately after inclusion (t= 0w), after 8 weeks (t= 8w, 2nd baseline), after 8 weeks of training (t= 16w), after 16 weeks of training (t= 24w), 16 weeks after the end of training (t= 40w) | 
| Risk for future work disability due to low back pain | Participants will be asked to complete the short version of the Örebro Musculoskeletal Pain Screening Questionnaire | Controls: once, immediately after inclusion, Patients: 5 times, immediately after inclusion (t= 0w), after 8 weeks (t= 8w, 2nd baseline), after 8 weeks of training (t= 16w), after 16 weeks of training (t= 24w), 16 weeks after the end of training (t= 40w) | 
| Pain-related fear of movement | Participants will be asked to complete the Tampa Scale for Kinesiophobia. | Controls: once, immediately after inclusion, Patients: 5 times, immediately after inclusion (t= 0w), after 8 weeks (t= 8w, 2nd baseline), after 8 weeks of training (t= 16w), after 16 weeks of training (t= 24w), 16 weeks after the end of training (t= 40w) | 
| Fear-avoidance beliefs about physical activity and work | Participants will be asked to complete the Fear-Avoidance Beliefs Questionnaire. | Controls: once, immediately after inclusion, Patients: 5 times, immediately after inclusion (t= 0w), after 8 weeks (t= 8w, 2nd baseline), after 8 weeks of training (t= 16w), after 16 weeks of training (t= 24w), 16 weeks after the end of training (t= 40w) | 
| Pain catastrophizing | Participants will be asked to complete the Pain Catastrophizing Scale. | Controls: once, immediately after inclusion, Patients: 5 times, immediately after inclusion (t= 0w), after 8 weeks (t= 8w, 2nd baseline), after 8 weeks of training (t= 16w), after 16 weeks of training (t= 24w), 16 weeks after the end of training (t= 40w) | 
| Anxiety and depression | Participants will be asked to complete the Hospital Anxiety and Depression Scale. | Controls: once, immediately after inclusion, Patients: 5 times, immediately after inclusion (t= 0w), after 8 weeks (t= 8w, 2nd baseline), after 8 weeks of training (t= 16w), after 16 weeks of training (t= 24w), 16 weeks after the end of training (t= 40w) | 
| Habitual physical activity | Participants will be asked to complete the Baecke Questionnaire. | Controls: once, immediately after inclusion, Patients: 5 times, immediately after inclusion (t= 0w), after 8 weeks (t= 8w, 2nd baseline), after 8 weeks of training (t= 16w), after 16 weeks of training (t= 24w), 16 weeks after the end of training (t= 40w) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Proprioceptive postural control, Muscle volume, Muscle activation, Muscle oxygenation, Muscle fiber type composition, Proprioceptive training