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

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.