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

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.

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 \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