Exercise Therapy for Recurrent Low Back Pain: Unraveling the Puzzle of Peripheral Muscle and Central Brain Changes (B670201420984)

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.

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.

Eligibility Criteria:
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