Effects of the Spinal Manipulative Therapy and Myofascial Release on Pain Threshold, Muscle Function and Balance of Individuals With Non-specific Chronic Low Back Pain: Randomized Controlled Trial

The aim will be to compare a experimental group submitted to a protocol of spinal manipulation and myofascial release; and a control group composed by spinal manipulation only, in individuals with chronic non-specific low back pain. This is a randomized controlled trial, characterized by the application of manual therapy, in two modalities: spinal manipulation plus myofascial release and spinal manipulation alone. Participants will be enrolled and randomly allocated into two groups: 1) spinal manipulation plus myofascial release, totaling 6 sessions, 2x/week, for 3 weeks; 2) spinal manipulation: 6 sessions, 2x/week, for 3 weeks. Participants will be evaluated in two different moments: 1) Baseline (pre-intervention); 2) at the end of intervention period (3 weeks); and 3) after 3 months follow-up. The primary outcomes will be pain intensity (measured in centimeters with the visual analogue scale - VAS) and disability (measured by the Quebec questionnaire - QDS). The secondary outcomes will be muscle fatigue (measured by the Biering-Sorensen test), postural balance (measured by the Y Balance test), pain threshold (algometry, in kgf) and perception of recovery (Likert scale of 6-points) and health status (measured by the Eq5d3L questionnaire). Data analysis will be performed with the SPSS (Statistical Package for the Social Sciences) software version 24.0. Data normality assumptions will be confirmed by the Shapiro Wilk test. If the assumptions were met, a mixed ANOVA with repeated measures will be adopted, based on the outcomes and the independent variables (groups), for the comparison between pre-intervention and post-intervention. Spinal manipulation plus myofascial release is expected to have better effects than spinal manipulation alone, associated with the outcomes of interest.