Non-specific low back pain (LBP) is a very prevalent health condition and is highly associated with disability worldwide. There is evidence that patients with non-specific LBP may have impairments in the control of postural muscles. In this way, motor control exercises (MCE) may be an interesting alternative in the treatment of patients with non-specific LBP. In addition, the association of MCE and photobiomodulation therapy (PBMT) may potentiate its benefits, since PBMT has ergogenic effects. Therefore, the aim of this study is to evaluate the ergogenic effects of PBMT, using low-level laser therapy, when associated with MCE in patients with chronic non-specific low back pain.

This is a randomized, triple-blind (patients, therapists, outcome assessors), placebo-controlled trial, with voluntary patients with chronic non-specific low back pain. One hundred and forty-eight patients will be randomly allocated to two treatment groups: Placebo PBMT associated with MCE or Active PBMT associated with MCE. Treatment will be performed twice a week (on non-consecutive days), for 6 weeks, yielding 12 treatment sessions. Placebo PBMT or Active PBMT will be applied before the MCE protocol.

The clinical outcomes will be obtained at the end of treatment (6 weeks), one month after the end of treatment, 3, 6 and 12 months after randomization. The biochemical outcome will be obtained only after the end of treatment. The remaining outcomes will be obtained after the end of treatment, one month after the end of treatment, 3, 6 and 12 months after randomization.

The data will be collected by a blinded assessor. The statistical analysis will follow the intention-to-treat principles and the between-group differences will be calculated using two-way repeated measures ANOVA.

The project was also approved by the Research Ethics Committee from Universidade Nove de Julho, under the number 5.289.714.

Board Affiliation: Comissão Nacional de Ética em Pesquisa (CONEP) Phone: +55113385-9010 - Email: comitedeetica@uninove.br Address: Vergueiro nº 235/249. Liberdade, Sao Paulo, Sao Paulo, Brazil

Inclusion Criteria:

• patients seeking care for chronic non-specific low back pain (defined as pain or discomfort between the costal margins and the inferior gluteal folds, with or without referred symptoms in the lower limbs, for at least 3 month);
• with a pain intensity of at least 3 points measured by a 0-10 points pain numerical rating scale;
• aged between 18 and 65 years;
• able to read Portuguese.

Exclusion Criteria:

• evidence of nerve root compromise (i.e. one or more of motor, reflex or sensation deficit);
• serious spinal pathology (such as fracture, tumor, inflammatory and infectious diseases);
• patients with severe skin diseases (eg, skin cancer, erysipelas, severe eczema, severe dermatitis, severe psoriasis and severe hives lupus);
• decompensated severe cardiovascular and metabolic diseases;
• previous back surgery;
• patients with cancer;
• body mass index (BMI) ≥ 30.
• pregnancy.

The IPD will be available on reasonable request.

The data will become available during five years after the study completion

All IPD that underlie results in a publication will be available on reasonable request.