The purpose of this study will be to investigate the effects of lumbar strengthening training combined with photobiomodulation therapy (PBMT) therapy by light-emitting diode (LED) on functional and psychological aspects in young and older adults with chronic non-specific low back pain. Initially, all participants will be submitted for a 2-wk familiarization period with physical tests, and then randomized into two groups (N = 16/group): lumbar strengthening training combined with LED PBMT (TR+LED) and lumbar strengthening training combined with placebo PBMT (TR+PLA). Both groups will be submitted to a supervised 16-wk training program (3 x/week) involving a specific lumbar extension exercise on the Roman bench and four complementary exercises to improve core strength and spine stabilization. The groups will receive their respective PBMT (LED or placebo) 30 minutes before each training session, through a device containing 264 LEDs (132 LEDs of 660 nm and 132 LEDs of 850 nm), which will be placed on the lumbar region (between L1 and L5) with the participants lying in the prone position. The placebo LED will be applied with the device turned off. Participans will be blinded to PBM treatments. The following variables will be assessed at pre and post-training: anthropometric, body composition by bioimpedance, level of physical activity by International Physical Activity Questionnaire (IPAQ), maximal voluntary isometric contraction (MVIC) for lumbar extension exercise, short physical performance battery (SPPB), postural balance on a force platform, Schober test for lumbar spine flexion, Tampa Scale of kinesiophobia (TSK), Fear Avoidance Beliefs Questionnaire (FABQ), pain catastrophizing scale (PCS), quality of life by WHOQOL, oswestry disability index (ODI), Roland Morris disability questionnaire (RMDQ), McGILL pain questionnaire, and visual analogue scale (VAS). Shapiro-Wilk and Levene tests will be used to test the normality and homogeneity of the measurements, respectively. Two-way ANOVA (group x time) tests for repeated measures will be performed to assess changes over time and between groups for all dependent variables. Violation of sphericity will adjust using Greenhouse-Geisser correction. The Bonferroni post-hoc test will detect specific differences between groups. When appropriate, the percentage of change (∆%) will be reported according to the following equation: ∆% = [(pre-average post average) / pre-average mean] × 100. Values will be express as mean ± standard deviation. O significance level α will be 0.05.
The present project aims to investigate the effects of lumbar strengthening training combined with photobiomodulation therapy (PBMT) on functional and psychological aspects in young and older adults with chronic non-specific low back pain. We hypothesized that lumbar strengthening training combined with PBMT should promote greater improvement on functional and psychological variables compared to strengthening training alone (placebo PBMT).