The purpose of this study is to analyze the effectiveness of a three manipulative therapy techniques in People with Chronic Low Back Pain.

Objective: To analyze the effectiveness of a three manipulative therapy techniques in individuals with chronic non-specific low back pain of mechanical etiology.

Design: Randomized clinical trial. Setting: Almeria, South Spain. Participants: Sixty two with chronic non-specific low back pain will be randomly assigned to an experimental or control group.

Intervention: For 3-week, the experimental group will undergo treatment comprising 3 sessions (1/week) of manipulative therapy techniques in the lumbar and sacral areas, and the control group will receive a functional technique in the lumbar area.

Main Outcome Measures: Oswestry disability index, pain visual analogue scale, Tampa scale for kinesiophobia, Roland-Morris disability questionnaire, McQuade test, quality of life scores and the range of trunk anteflexion motion, which were all assessed before the treatment and immediately after the last treatment session.

The primary outcome measure is the change in the RMDQ score at the end of the 3 weeks study period. A difference of 2.5 point is considered to be the minimum clinically important difference in the RMDQ score. A sample size of 62 patients (31 per group) would enable detection of a 2.5 point difference between groups given 80-90% power, a 5% (two-tailed) significance level, and a conservative standard derivation of 5 points. Key baseline demographic variables and clinical measure scores will be compared between groups by using independent Student t tests for continuous data and chi-square tests for categorical data. Separate 2x2 mixed model ANOVA with repeated measurements for the time factor need to be conducted in order to test between-groups differences in visual analogue scale, McQuade test, range of trunk anteflexion motion, Oswestry disability index, Roland Morris disability questionnaire, Tampa scale for kinesiophobia, and quality of life as the dependent variables, with group (functional technique or three manipulative therapy techniques) as the between subjects variable and time (baseline, post-treatment). A paired t-test will perform to test within-group differences in score changes from pre- to post-treatment. Effect size will test using Cohen's d. p = 0.05 will be considered significant in all tests.

Inclusion Criteria:

• Low back pain for ≥ 3 months.
• Score ≥4 on the Roland Morris disability questionnaire.
• No undergoing another physical therapy treatment.
• Inability to achieve lumbar muscle flexion-relaxation in trunk flexion

Exclusion Criteria:

• Clinical signs of radiculopathy.
• Presence of lumbar stenosis.
• Fibromyalgia.
• Spondylolisthesis.
• History of spinal surgery.
• Treatment with corticosteroids in the past two weeks.
• Disease of the central or peripheral nervous system.