Effect of brain and nerve electrical stimulation combined with exercise for back pain.

INTERVENTION: Randomized, placebo (sham)‐controlled clinical trial with four parallel arms allocated in a 1:1:1:1 ratio, totaling 76 participants, 19 per group. The randomization sequence is electronically generated through the Randomizer.org platform by a researcher responsible for applying the interventions, who is not involved in outcome assessment. The study is double‐blind, with participants and the outcome assessor kept blinded to group allocation. In Group 1, participants receive active transcranial direct current stimulation, with the anodal electrode positioned over the supplementary motor area identified using the 10‐20 electroencephalography system, at an intensity of 2 mA for 20 minutes, associated with active peripheral electrical stimulation applied bilaterally over the external oblique muscle, at a frequency of 100 Hz, also for 20 minutes, and with segmental stabilization training, performed individually and supervised by a physical therapist, focusing on the coordinated recruitment of the abdominal wall muscles and the respiratory cycle. In Group 2, participants receive active transcranial direct current stimulation associated with sham peripheral electrical stimulation and the same segmental stabilization training. In Group 3, participants receive sham transcranial direct current stimulation associated with active peripheral electrical stimulation and the same segmental stabilization training. In Group 4, participants receive sham transcranial direct current stimulation associated with sham peripheral electrical stimulation and the same segmental stabilization training. All interventions take place over four weeks, with three weekly sessions of twenty minutes each. CONDITION: C23.888.592.612 Low Back Pain ; pain PRIMARY OUTCOME: Assess the intensity of low back pain. It will be verified using the Numeric Pain Rating Scale (0 to 10 points). A minimum reduction of 2 points on the Numeric Pain Rating Scale is expected in the groups receiving active transcranial direct current stimulation (tDCS) and/or active peripheral electrical stimulation (PES), compared to the sham group, at the post‐intervention (T1), 1‐month (T2), 3‐month (T3), and 6‐month (T4) time points INCLUSION CRITERIA: Adults of both sexes; aged 18 years or older; nonspecific chronic low back pain; pain duration of 3 months or longer SECONDARY OUTCOME: Assess low back pain across its sensory, affective, and evaluative dimensions. It will be verified using the McGill Pain Questionnaire (version validated by Menezes Costa et al., 2011). A statistically significant difference in the group×time interaction (p < 0.05) is expected, with lower scores in the groups receiving active transcranial direct current stimulation (tDCS) and/or active peripheral electrical stimulation (PES) compared to the sham group. Assess functional disability related to low back pain. It will be verified using the Roland‐Morris Disability Questionnaire. A statistically significant difference in the group×time interaction (p < 0.05) is expected, with lower scores in the active groups compared to the sham group. Assess lower‐limb functional performance. It will be verified using the 5‐repetition sit‐to‐stand test (5R‐STS), applied at T0, T1, and T2. A statistically significant difference in the group×time interaction (p < 0.05) is expected, with shorter execution time in the active groups compared to the sham group