The forgotten role of back muscle characteristics to tailor exercise therapy for recurrent non-specific low back pain: Study protocol for the Back-to-Back study

Abstract

Background and aims: Current treatments for non-specific low back pain (NSLBP) have only limited effects. Identifying phenotypes of patients that share underlying mechanisms towards which clinicians could direct treatment could improve the effects. Previous studies found macroscopic, microscopic, electrophysiological, and proprioceptive changes in the back muscles of patients with NSLBP. However, no studies delineated NSLBP phenotypes based on back muscle characteristics.

Methods: We will evaluate various characteristics of the lumbar multifidus and erector spinae in 90 patients with NSLBP and 55 healthy controls: muscle volume with 3D freehand ultrasound, muscle fiber type composition with minimally-invasive muscle biopsies, proprioceptive use during postural control by applying muscle vibration during standing on a force plate, and muscle activation and oxygenation with electromyography and near-infrared spectroscopy (Fig. 1). We will determine the most discriminating muscle characteristics between patients with NSLBP and controls, based upon which phenotypes will be delineated. Then, the patients with NSLBP will be randomized into two groups receiving a 16-week program of proprioceptive training or resistance training. The effect of both programs on back muscle characteristics and disability will be evaluated halfway the program, at the end of the program, and 16 weeks after the end of training.

Results: The protocol is submitted to the Ethical Committees of UZ/KU Leuven and UHasselt. The study is funded by the Research Foundation - Flanders (FWO) (G072122N). Participant recruitment and data collection are anticipated to start in March 2023.

Conclusions: We expect the results to help improve the patient-tailored exercise therapy for NSLBP.