The relevance of this study is to determine the efficacy of two osteopathic techniques - Thrust Technique and Muscle Energy Technique (MET) - in improving of neuromuscular component of the trunk and clinical symptoms in adult workers with Chronic Low Back Pain (CLBP). Few studies have investigated and compared the physiological responses of these techniques quantitatively, and no published study has compared their effects in low back pain subjects in terms of symptoms, postural balance and muscle activation. The main outcomes will be computed by electromyography measurement so that to assess the trunk neuromuscular activation pattern as well as by force platform parameters for determining of postural control. Clinical symptoms such as pain intensity, perception of disability and fear and avoidance will also be computed.

This is the first study to compare these two osteopathic techniques using the main biological outcomes related to trunk neuromuscular function.

The purpose of this study is to assess the efficacy of two osteopathic techniques (Thrust and MET) on CLBP adult workers treatment.

A total of 15 male participants with chronic low back pain, volunteers, active workers aged from 35 to 55 years (in aging process) will be recruited by convenience from the community local. All participants will sign an informed consent form approved by the North of Parana University Ethics Committee for Research on Human Subjects. The intervention will follow the CONSORT recommendations for randomized controlled trials. All baseline testing and evaluation will be performed by a blinded evaluator to the study intervention. The sample will be randomized in two groups from crossover design: Group #1), which will receive the Thrust technique applied at the level of dysfunction; and Group #2, which will receive the Muscle Energy Technique, also applied at the level of dysfunction. The allocation will be printed in cards by sequentially numbered in opaque envelopes.

The treatment (intervention) will occur in 2 phases of 3 weeks each one. The participants will receive only one of techniques in each phase, and after one rest week (washout) they will receive the other technique (crossover), totaling 7 weeks. In this study, both techniques will be applied at the lumbar vertebral level that present the dysfunction which will be diagnosed in the specific evaluation, performed by two specialized physiotherapists in osteopathy. Before and after the manipulation (with Thrust or MET) all participants will be evaluated in 2 tasks - bipedal without load and bipedal with load (10% of body mass) - on the force platform. Parallel to the tasks, the recording of the measurements of EMG surface will be computed to determine the pattern of the trunk neuromuscular activation in amplitude of the RMS signal as well as muscle fatigue through the median frequency parameters.

Before performing the tasks on the force platform, a maximum voluntary isometric contraction will be performed for the back (paravertebral) and abdominal (rectus) muscles in order to normalize the signal EMG for determining of the level muscular activity during each task (with or without load). After the intervention, the immediate and final revaluations will include all the used measures in the initial evaluation, such as muscle activation of trunk (EMG), balance (force platform), and clinical symptoms of pain (Visual Analogue Scale and McGill Short Questionnaire), psychosomatic factors (Fear and Avoidance Believe Questionnaire) and disability (Roland Morris Questionnaire).

For the analysis a two-way ANOVA will be used for each dependent variable to compare the two groups (G1 versus G2) in both situations (pre and post-immediate, and after 15 days) in the clinical measurements, postural balance and EMG. The size effect also will be computed to determine the rate of the changes observed.

Inclusion Criteria:

• Chronic low back pain at least for three months.
• Low back pain of unknown mechanical origin without irradiation to the lower limbs.
• Workers with chronic low back pain at least three months.
• Do not be participating in rehabilitation programs.
• Do not have practiced regular physical activity in the past 3 months.

Exclusion Criteria:

• Manual therapy treatment in the past 90 days.
• Discal herniation diagnosis.
• Lumbar radiculopathy and / or nerve root compression.
• Lumbar stenosis.
• Lumbar surgery.
• Nerve root entrapment.
• Neurological and endocrine.
• Osteoporosis.
• Rheumatoid arthritis.
• Spinal osteomyelitis.
• Spondylolysis.
• Spondylolisthesis.
• Tumors.
• Vertebral fracture.
• No current sports or treatment in Physiotherapy, Pilates Method or Manual Therapy.