Exercise Therapy for Recurrent Low Back Pain: Unraveling the Puzzle of Peripheral Muscle and Central Brain Changes

Low Back Pain, Recurrent Clinical Trial

— ExTraS  

Official title:

Efficacy of Specific Skilled Motor Versus General Exercise Training on Peripheral Muscle and Central Brain Alterations in Patients With Recurrent Low Back Pain

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT05706103
• Other study ID #: B670201420984
• Secondary ID: U1111-1283-4631
• Status: Recruiting
• Phase: N/A
• Start date: January 4, 2021
• Est. completion date: December 31, 2025

Study information

• Verified date: January 2024
• Source: University Ghent
• Contact: Jessica van Oosterwijck, Prof
• Phone: +3293326919
• Email: Jessica.VanOosterwijck[@]UGent.be
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Exercise therapy has been shown to be effective in decreasing pain and improving function for patients with recurrent low back pain (LBP). Research on the mechanisms that trigger and/or underlie the effects of exercise therapy on LBP problems is of critical importance for the prevention of recurring or persistence of this costly and common condition. One factor that seems to be crucial within this context is the dysfunction of the back muscles. Recent pioneering results have shown that individuals with recurring episodes of LBP have specific dysfunctions of these muscles (peripheral changes) and also dysfunctions at the cortical level (central changes). This work provides the foundation to take a fresh look at the interplay between peripheral and central aspects, and its potential involvement in exercise therapy. The current project will draw on this opportunity to address the following research questions: What are the immediate (after a single session) and the long-term effects (after 18 repeated sessions) of exercise training on: (1) back muscle structure; (2) back muscle function; (3) the structure of the brain; (4) and functional connectivity of the brain. This research project also aims to examine whether the effects are dependent on how the training was performed. Therefore a specific versus a general exercise program will be compared.

Description:

Although the cause of persistent non-specific LBP remains unknown, structural and functional alterations of the brain and paravertebral muscles have been proposed as underlying mechanisms. As it is hypothesized that these alterations contribute to, or maintain non-specific LBP, exercise therapy is a key element in the rehabilitation of reoccurring LBP. Specific training of sensorimotor control of the lumbopelvic region (i.e. specific skilled motor training) has shown to decrease pain and disability in patients with LBP, but has not been found superior to other forms of exercise training regarding improvements in clinical outcome measures. On the other hand, this type of training seems to differentially impact the recruitment of the back muscles compared to general exercise training. However, research using multiple treatment sessions and including follow-up outcome assessments is scarce. Furthermore, it is unknown if improvements may be attributed to measurable peripheral changes in the muscle and/or central neural adaptations in the brain. The primary aim of this study is to examine the short and long-term effects of specific skilled motor control training versus unspecific general extension training on pain, functional disability, brain structure/function and muscle structure/function in recurrent LBP patients.

Method: In this double-blind, randomized controlled clinical trial 62 recurrent LBP patients will be randomly allocated (1:1) to receive either specific skilled motor training (i.e. the experimental group) or general extension training (i.e. control group). Each training group will receive 13 weeks of treatment, during which a total of 18 supervised treatment sessions will be delivered in combination with an individualized home-exercise program. Both groups will first receive low-load training (i.e. at 25-30% of the individual's repetition maximum, sessions 1-9) followed by high-load training (i.e. at 40-60% of the individual's one repetition maximum, sessions 10-18). Primary outcome measures include: LBP-related pain and disability (RMDQ, NRS and Margolis pain diagram), lumbar muscle structure and function (Dixon MRI and mf-MRI) and brain structure and function (MRI, DTI and fMRI). Secondary measures include: lumbopelvic control and proprioception (thoracolumbar dissociation test and position-reposition test), trunk muscle activity (RAM and QFRT) and psychosocial factors, including measures of physical activity (IPAQ-LF, SF-36), pain cognitions and perceptions (PCS, PCI and PVAQ), anxiety and depression (HADS), and kinesiophobia (TSK). Experimental data collection will be performed at baseline, immediately following the low-load training (i.e. after the 9th supervised treatment session), following the high-load training (i.e. after the 18th supervised treatment session), and at 3 months follow-up. Experimental data collection will comprise of magnetic resonance imaging of the brain and trunk muscles, clinical assessments assessing muscle function, and a battery of questionnaires evaluating psychosocial factors.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 62
• Est. completion date: December 31, 2025
• Est. primary completion date: December 31, 2025
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years to 45 Years

Eligibility

Inclusion Criteria:

• History of non-specific recurrent LBP with the first onset being at least 6 months ago

• At least 2 episodes of LBP/year, with an 'episode' implying pain lasting a minimum of 24 hours which is preceded and followed by at least 1 month without LBP

• Minimum LBP intensity during episodes should be =2/10 on a numeric rating scale (NRS) from 0 to 10

• During remission the NRS intensity for LBP should be 0.

• LBP should be of that severity that it limits activities of daily living

• LBP should be of that severity that a (para)medic has been consulted at least once regarding the complaints

• Flexion pattern of LBP

Exclusion Criteria:

• Chronic LBP (i.e. duration remission <1 month)

• Subacute LBP (i.e. first onset between 3 and 6 months ago)

• Acute (i.e. first onset <3 months ago) LBP

• Specific LBP (i.e. LBP proportionate to an identifiable pathology, e.g. lumbar radiculopathy)

• Patients with neuropathic pain

• Patients with chronic widespread pain as defined by the criteria of the 1990 ACR (i.e. fibromyalgia)

• A lifetime history of spinal traumata (e.g. whiplash), surgery (e.g. laminectomy) or deformations (e.g. scoliosis)

• A lifetime history of respiratory, metabolic, neurologic, cardiovascular, inflammatory, orthopedic or rheumatologic diseases

• Concomitant therapies (i.e. rehabilitation, alternative medicine or therapies)

• Contra-indications for MRI (e.g. suffering from claustrophobia, the presence of metallic foreign material in the body, BMI >30kg/m²)

• Professional athletes

• Pregnant women

• Breastfeeding women

• Women given birth in the last year before enrolment

Related Conditions & MeSH terms

• Back Pain
• Low Back Pain
• Low Back Pain, Recurrent
• Recurrence

Intervention

Behavioral:
• Specific skilled motor training
Participants allocated to the skilled motor training group will receive sensorimotor training of the intrinsic muscles of the lumbopelvic region, namely the multifidus, transversus abdominis, and pelvic floor muscles.
• General extension training
Participants allocated to the general extension training group will receive general training exercises using the David Back equipment from the Back Unit at Ghent University Hospital

Locations

Country	Name	City	State
Belgium	Ghent University, vakgroep revalidatiewetenschappen	Ghent	Oost-Vlaanderen

Sponsors (2)

Lead Sponsor	Collaborator
University Ghent	Fund for Scientific Research, Flanders, Belgium

Country where clinical trial is conducted

Belgium, 

References & Publications (45)

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* Note: There are 45 references in all — Click here to view all references

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Brain macro-structure	Whole brain T1-weighted structural MRI will be acquired.	Baseline
Primary	Brain macro-structure	Whole brain T1-weighted structural MRI will be acquired.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Primary	Brain macro-structure	Whole brain T1-weighted structural MRI will be acquired.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Primary	Brain macro-structure	Whole brain T1-weighted structural MRI will be acquired.	At 3 months follow-up
Primary	Brain micro-structure	Whole-brain T2-weighted images will be obtained.	Baseline
Primary	Brain micro-structure	Whole-brain T2-weighted images will be obtained.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Primary	Brain micro-structure	Whole-brain T2-weighted images will be obtained.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Primary	Brain micro-structure	Whole-brain T2-weighted images will be obtained.	At 3 months follow-up
Secondary	Functional brain connectivity	Resting-state functional MRI will be performed to acquire insight into subnetworks relating to sensorimotor control and pain processing.	Baseline
Secondary	Functional brain connectivity	Resting-state functional MRI will be performed to acquire insight into subnetworks relating to sensorimotor control and pain processing.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Functional brain connectivity	Resting-state functional MRI will be performed to acquire insight into subnetworks relating to sensorimotor control and pain processing.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Functional brain connectivity	Resting-state functional MRI will be performed to acquire insight into subnetworks relating to sensorimotor control and pain processing.	At 3 months follow-up
Secondary	Lumbar muscle structure	T1-weighted Dixon MRI will be performed.	Baseline
Secondary	Lumbar muscle structure	T1-weighted Dixon MRI will be performed.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Lumbar muscle structure	T1-weighted Dixon MRI will be performed.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Lumbar muscle structure	T1-weighted Dixon MRI will be performed.	At 3 months follow-up
Secondary	Lumbar muscle function	T2-weighted mf-MRI will be conducted.	Baseline
Secondary	Lumbar muscle function	T2-weighted mf-MRI will be conducted.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Lumbar muscle function	T2-weighted mf-MRI will be conducted.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Lumbar muscle function	T2-weighted mf-MRI will be conducted.	At 3 months follow-up.
Secondary	Lumbopelvic control	Lumbopelvic control will be examined by means of a clinical thoracolumbar dissociation test which assesses the quality of performance of lumbopelvic motion with limited motion at the thoracolumbar junction.	Baseline
Secondary	Lumbopelvic control	Lumbopelvic control will be examined by means of a clinical thoracolumbar dissociation test which assesses the quality of performance of lumbopelvic motion with limited motion at the thoracolumbar junction.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Lumbopelvic control	Lumbopelvic control will be examined by means of a clinical thoracolumbar dissociation test which assesses the quality of performance of lumbopelvic motion with limited motion at the thoracolumbar junction.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Lumbopelvic control	Lumbopelvic control will be examined by means of a clinical thoracolumbar dissociation test which assesses the quality of performance of lumbopelvic motion with limited motion at the thoracolumbar junction.	At 3 months follow-up.
Secondary	Lumbopelvic proprioception	To evaluate lumbar proprioception, the position-reposition accuracy of the lumbar spine will be determined.	Baseline
Secondary	Lumbopelvic proprioception	To evaluate lumbar proprioception, the position-reposition accuracy of the lumbar spine will be determined.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Lumbopelvic proprioception	To evaluate lumbar proprioception, the position-reposition accuracy of the lumbar spine will be determined.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Lumbopelvic proprioception	To evaluate lumbar proprioception, the position-reposition accuracy of the lumbar spine will be determined.	At 3 months follow-up.
Secondary	Anticipatory postural adjustments	To examine anticipatory postural adjustments (APAs) trunk muscle onset latencies in response to internal-induced perturbations will be measured by means of surface electromyography (EMG). APAs will be measured by inducing internal perturbations in the trunk muscles during a reliable and valid unilateral rapid arm movement task (RAM).	Baseline
Secondary	Anticipatory postural adjustments	To examine anticipatory postural adjustments (APAs) trunk muscle onset latencies in response to internal-induced perturbations will be measured by means of surface electromyography (EMG). APAs will be measured by inducing internal perturbations in the trunk muscles during a reliable and valid unilateral rapid arm movement task (RAM).	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Anticipatory postural adjustments	To examine anticipatory postural adjustments (APAs) trunk muscle onset latencies in response to internal-induced perturbations will be measured by means of surface electromyography (EMG). APAs will be measured by inducing internal perturbations in the trunk muscles during a reliable and valid unilateral rapid arm movement task (RAM).	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Anticipatory postural adjustments	To examine anticipatory postural adjustments (APAs) trunk muscle onset latencies in response to internal-induced perturbations will be measured by means of surface electromyography (EMG). APAs will be measured by inducing internal perturbations in the trunk muscles during a reliable and valid unilateral rapid arm movement task (RAM).	At 3 months follow-up
Secondary	Compensatory postural adjustments	To examine compensatory postural adjustments (CPAs), trunk muscle onset latencies in response to external-induced perturbations will be measured by means of surface electromyography (EMG). CPAs will be measured by using external perturbations of trunk muscles during a quick-force-release test (QFRT).	Baseline
Secondary	Compensatory postural adjustments	To examine compensatory postural adjustments (CPAs), trunk muscle onset latencies in response to external-induced perturbations will be measured by means of surface electromyography (EMG). CPAs will be measured by using external perturbations of trunk muscles during a quick-force-release test (QFRT).	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Compensatory postural adjustments	To examine compensatory postural adjustments (CPAs), trunk muscle onset latencies in response to external-induced perturbations will be measured by means of surface electromyography (EMG). CPAs will be measured by using external perturbations of trunk muscles during a quick-force-release test (QFRT).	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Compensatory postural adjustments	To examine compensatory postural adjustments (CPAs), trunk muscle onset latencies in response to external-induced perturbations will be measured by means of surface electromyography (EMG). CPAs will be measured by using external perturbations of trunk muscles during a quick-force-release test (QFRT).	At 3 months follow-up
Secondary	Nociceptive flexion reflex - threshold	The NFR will be elicited in the dominant leg by transcutaneous electrical stimulation of the sural nerve in its retromalleolar path using a stimulation bar electrode connected to a constant current stimulator. Surface EMG electrodes will be placed on the skin of the muscle belly of the ipsilateral biceps femoris.	Baseline
Secondary	Nociceptive flexion reflex - threshold	The NFR will be elicited in the dominant leg by transcutaneous electrical stimulation of the sural nerve in its retromalleolar path using a stimulation bar electrode connected to a constant current stimulator. Surface EMG electrodes will be placed on the skin of the muscle belly of the ipsilateral biceps femoris.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Nociceptive flexion reflex - threshold	The NFR will be elicited in the dominant leg by transcutaneous electrical stimulation of the sural nerve in its retromalleolar path using a stimulation bar electrode connected to a constant current stimulator. Surface EMG electrodes will be placed on the skin of the muscle belly of the ipsilateral biceps femoris.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Nociceptive flexion reflex - threshold	The NFR will be elicited in the dominant leg by transcutaneous electrical stimulation of the sural nerve in its retromalleolar path using a stimulation bar electrode connected to a constant current stimulator. Surface EMG electrodes will be placed on the skin of the muscle belly of the ipsilateral biceps femoris.	At 3 months follow-up
Secondary	Nociceptive flexion reflex - temporal summation	Five 1ms rectangular wave pulse train will be administered 3 times at a frequency of 2 Hz at a constant stimulation intensity. This procedure will be repeated 5 times.	Baseline
Secondary	Nociceptive flexion reflex - temporal summation	Five 1ms rectangular wave pulse train will be administered 3 times at a frequency of 2 Hz at a constant stimulation intensity. This procedure will be repeated 5 times.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Nociceptive flexion reflex - temporal summation	Five 1ms rectangular wave pulse train will be administered 3 times at a frequency of 2 Hz at a constant stimulation intensity. This procedure will be repeated 5 times.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Nociceptive flexion reflex - temporal summation	Five 1ms rectangular wave pulse train will be administered 3 times at a frequency of 2 Hz at a constant stimulation intensity. This procedure will be repeated 5 times.	At 3 months follow-up
Secondary	Conditioned pain modulation	The conditioning stimulus will comprise of immersion of the non-dominant hand until the proximal wrist crease in a hot circulating water bath of 45.5°C during 6 minutes. The test stimulus will comprise of pressure pain threshold (PPT) assessments (as described above) during and after completion of the conditioning stimulus. Before, after 2 min of immersion and 2 minutes after completion of immersion, the test stimulus will be repeated twice at each test location at the dominant body side.	Baseline
Secondary	Conditioned pain modulation	The conditioning stimulus will comprise of immersion of the non-dominant hand until the proximal wrist crease in a hot circulating water bath of 45.5°C during 6 minutes. The test stimulus will comprise of pressure pain threshold (PPT) assessments (as described above) during and after completion of the conditioning stimulus. Before, after 2 min of immersion and 2 minutes after completion of immersion, the test stimulus will be repeated twice at each test location at the dominant body side.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Conditioned pain modulation	The conditioning stimulus will comprise of immersion of the non-dominant hand until the proximal wrist crease in a hot circulating water bath of 45.5°C during 6 minutes. The test stimulus will comprise of pressure pain threshold (PPT) assessments (as described above) during and after completion of the conditioning stimulus. Before, after 2 min of immersion and 2 minutes after completion of immersion, the test stimulus will be repeated twice at each test location at the dominant body side.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Conditioned pain modulation	The conditioning stimulus will comprise of immersion of the non-dominant hand until the proximal wrist crease in a hot circulating water bath of 45.5°C during 6 minutes. The test stimulus will comprise of pressure pain threshold (PPT) assessments (as described above) during and after completion of the conditioning stimulus. Before, after 2 min of immersion and 2 minutes after completion of immersion, the test stimulus will be repeated twice at each test location at the dominant body side.	At 3 months follow-up
Secondary	Anxiety and depression	Hospital Anxiety and depression scale (HADS)	Baseline
Secondary	Anxiety and depression	Hospital Anxiety and depression scale (HADS)	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Anxiety and depression	Hospital Anxiety and depression scale (HADS)	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Anxiety and depression	Hospital Anxiety and depression scale (HADS)	At 3 months follow-up
Secondary	Physical activity	International physical activity questionnaire - long form (IPAQ-LF)	Baseline
Secondary	Physical activity	International physical activity questionnaire - long form (IPAQ-LF)	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Physical activity	International physical activity questionnaire - long form (IPAQ-LF)	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Physical activity	International physical activity questionnaire - long form (IPAQ-LF)	At 3 months follow-up.
Secondary	Pain coping	Pain coping inventory (PCI), Pain Catastrophizing Scale (PCS)	Baseline
Secondary	Pain coping	Pain coping inventory (PCI), Pain Catastrophizing Scale (PCS)	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Pain coping	Pain coping inventory (PCI), Pain Catastrophizing Scale (PCS)	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Pain coping	Pain coping inventory (PCI), Pain Catastrophizing Scale (PCS)	At 3 months follow-up
Secondary	Pain catastrophizing	Pain Catastrophizing Scale (PCS)	Baseline
Secondary	Pain catastrophizing	Pain Catastrophizing Scale (PCS)	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Pain catastrophizing	Pain Catastrophizing Scale (PCS)	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Pain catastrophizing	Pain Catastrophizing Scale (PCS)	At 3 months follow-up
Secondary	Pain vigilance and awareness	Pain vigilance and awareness questionnaire (PVAQ)	Baseline
Secondary	Pain vigilance and awareness	Pain vigilance and awareness questionnaire (PVAQ)	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Pain vigilance and awareness	Pain vigilance and awareness questionnaire (PVAQ)	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Pain vigilance and awareness	Pain vigilance and awareness questionnaire (PVAQ)	At 3 months follow-up
Secondary	Kinesiophobia	Tampa Scale for Kinesiophobia (TSK)	Baseline
Secondary	Kinesiophobia	Tampa Scale for Kinesiophobia (TSK)	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Kinesiophobia	Tampa Scale for Kinesiophobia (TSK)	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Kinesiophobia	Tampa Scale for Kinesiophobia (TSK)	At 3 months follow-up
Secondary	Health status	Short Form Health Survey-36 items (SF-36)	Baseline
Secondary	Health status	Short Form Health Survey-36 items (SF-36)	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Health status	Short Form Health Survey-36 items (SF-36)	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Health status	Short Form Health Survey-36 items (SF-36)	At 3 months follow-up
Secondary	Low back pain related pain	LBP related pain intensity will be evaluated by using an 11 point NRS	Baseline
Secondary	Low back pain related pain	LBP related pain intensity will be evaluated by using an 11 point NRS	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Low back pain related pain	LBP related pain intensity will be evaluated by using an 11 point NRS	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Low back pain related pain	LBP related pain intensity will be evaluated by using an 11 point NRS	At 3 months follow-up
Secondary	Low back pain related disability	The Roland Morris Disability Questionnaire will be used to evaluate disability.	Baseline
Secondary	Low back pain related disability	The Roland Morris Disability Questionnaire will be used to evaluate disability.	After low-load training phase (i.e. after 9th supervised treatment session) assessed at approximately 8 weeks
Secondary	Low back pain related disability	The Roland Morris Disability Questionnaire will be used to evaluate disability.	After high-load training phase (i.e. after 18th supervised treatment session) assessed at approximately 13 weeks
Secondary	Low back pain related disability	The Roland Morris Disability Questionnaire will be used to evaluate disability.	At 3 months follow-up
Secondary	Low back pain recurrence	Self-report via telephone interview: (1) the number of episode(s), (2) the duration of the LBP episode(s), (3) pain intensity, measured with three NRS for average-, worst- and current pain during the LBP episode(s), (4) location and quality of pain (i.e. sharp, burning, etc. sensation), (5) subjects opinion about what caused the new episode of LBP, (6) degree of impairments in daily life activities due to the LBP, (7) whether participants sought treatment (i.e. physiotherapist, general practitioner, etc.) and (8) strategies to cope with the new LBP episode.	At 6 months follow-up
Secondary	Low back pain recurrence	Self-report via telephone interview: (1) the number of episode(s), (2) the duration of the LBP episode(s), (3) pain intensity, measured with three NRS for average-, worst- and current pain during the LBP episode(s), (4) location and quality of pain (i.e. sharp, burning, etc. sensation), (5) subjects opinion about what caused the new episode of LBP, (6) degree of impairments in daily life activities due to the LBP, (7) whether participants sought treatment (i.e. physiotherapist, general practitioner, etc.) and (8) strategies to cope with the new LBP episode.	At 12 months follow-up