Chronic low back pain (CLBP) remains a leading cause of disability worldwide and imposes a substantial personal and socioeconomic burden. Despite exercise being the first-line recommended intervention in clinical guidelines, its efficacy on pain relief remains modest and the hypoalgesia induced by exercise seems to be limited in individuals with musculoskeletal pain. Previous transcranial direct current stimulation (tDCS) studies have mainly targeted the motor cortex, yielding heterogeneous results, underscoring the need to evaluate alternative brain areas. Recently, tDCS studies targeting the dorsolateral prefrontal cortex (DLPFC) may enhance endogenous pain modulation and thereby potentiate the response to exercise. This study aims to compare the effects of adjunctive anodal DLPFC tDCS combined with a standardised exercise programme versus sham tDCS combined with the same exercise programme on pain and function in adults with CLBP.

This is a single-centre, triple-blinded, parallel-group randomised controlled trial. 48 participants with CLBP will be randomly assigned to receive either anodal tDCS over the left PFC combined with exercises, or sham tDCS combined with the same exercise programme, over nine sessions during a 3-week period. The primary outcome is the change in the multidimensional impact of CLBP, assessed using the Core Outcome Measures Index, from baseline to postintervention (week 4). Secondary outcomes include pain intensity, disability, psychological factors (fear-avoidance beliefs, catastrophising, anxiety, depression), measured at baseline, postintervention and at 12- and 24-week follow-up. Functional brain connectivity via electroencephalography and neuromuscular function of the erector spinae (flexion–relaxation phenomenon) will be measured at baseline and postintervention.

This study was approved by the Commission Cantonale d’Ethique de la Recherche sur l’être humain (CCER) in December 2022 (reference number: 2022-D0077). Written informed consent will be obtained from all participants. The results will be disseminated through peer-reviewed publications and presentations at national and international conferences.

NCT05757609.