Non-specific chronic low back pain is a common multifactorial condition common to the world population. It is defined as a pain and discomfort located below the ribs and above the gluteal folds that may or may not have referred pain in the leg for more than 12 weeks. Visceral manipulation is a manual therapy technique that aims to normalize mechanical, vascular and neurological dysfunctions of the viscera with the objective of improving its functioning. Visceral dysfunction may potentially activate or exacerbate the symptoms of low back pain in the presence of compromised movements between the internal organs and its connective tissues. There are two ways in which a change in visceral mobility could interfere with low back pain, referred visceral pain and central hypersensitivity. The first occurs due to neural convergence, since there is no spinocortical tract that only sends visceral or somatic afferences, its afferences are crossed in the dorsal horn of the spinal cord. The second is that the prolonged and continuous activation of nociceptors, due to the alteration in the mobility of the gastrointestinal and urinary system, can generate central hypersensitivity. Therefore, the investigators hypothesized that through the visceral manipulation the fascial adherences would lyse and the visceral spasms would demise, reducing the peripheral input, thus, lessening pain in the low back.

Ethical aspects: All volunteers will be informed about the experimental procedures that will be submitted, as well as the fact that these do not affect the participant's health. The participants will also be clarified as to the secrecy of the information collected during the study performance, protecting the identities of the participants. After agreeing to participate in the research, each volunteer will sign the Informed Consent Term, according to resolution 196/96 and update in resolution 466 in 2012 of the National Health Council.

Risks:The interventions offer no harm to the participant's health. There is the possibility of the participant feeling pain and / or tickling during abdominal palpation. If these sensations occur, the procedure will be stopped and tried again. If sensations persist and the participant can not support them the session will be rescheduled or the participant will be disconnected from the study as there is no other way to carry out the proposed therapy.

Benefits:There may be no direct or immediate benefits, however, it is expected that the proposed treatment will improve lumbar pain.

This study does not offer any type of health insurance, and also, it is the responsibility of the participant to get around and bear the costs of transportation to the place of collection of data.

Confidentiality and privacy of research participants will be guaranteed during all phases of the research. At any time the participant can withdraw consent to participate in the research without any kind of penalty.

The research team is committed to making the search results public, whether favorable or not.

It is worth noting that the placebo intervention procedures will always be performed in association with an active treatment, which makes its use of less impact to the patient. In addition, all patients will be informed of the use of this procedure prior to the initiation of the survey.

Criteria for suspending research: This research will be suspended in the event of researchers' deaths, closure of the research site or termination of the Term of Science of the Partner Condition and / or no volunteer to participate in the research.

Financing This study will be funded by the researchers themselves.

Source of Patients: Patients with chronic low back pain will be referred for screening from online surveys, third party indications, and from patients on the waiting list of the Heath Center of the University of Sorocaba. The screening, assessment and evaluation will be performed at the Health Nucleus and in the Integrated Human Movement Laboratory of the University of Sorocaba.

Procedure: The researchers will inform the study objectives and procedures to all patients. If the participants agree to participate, the participants will sign an informed consent form. After that, a therapist will assess them for demographic data and baseline measures, such as pain level (0-10 Numerical Pain Rating Scale), disability associated with low back pain (Roland-Morris Disability Questionnaire), and function (0-10 Patient-Specific Functional Scale)

Random Allocation: One of the researchers will create a randomization code with 1:1 allocation radio using Excel for Windows software. The codes will be the words "E" for experimental or "P" for placebo, then ithe codes will be sealed on opaque envelopes, thus ensuring the concealed allocation of participants to groups. At the first encounter with the treating therapist, patients will choose one of the envelopes on a table and give it to the therapist. The therapist will open it in a different room from the patient and allocate the patient to the group according to the randomization schedule.

Interventions: The volunteers will be allocated in the Experimental group or the Control Group. In the Experimental, the participants will receive the Standard care physiotherapy plus Active visceral manipulation, while the Control will receive Standard care physiotherapy and Placebo visceral manipulation. The standard care physiotherapy lasts 40 minutes and the visceral mobilisation takes around 10 minutes.

Blinding: The assessor and the therapist will be blind to each others work. Therefore the assessor will not have knowledge of the treatment allocation and will perform three assessments, the pre assessment, immediately after the last treatment and 1 week after the treatment. Similarly, the therapist will not know the pre- and post-assessment intervention. In addition, there will be only one assessor and one therapist for the research to decrease bias. To test the blinding, after the last treatment session, the assessor will write on the patient's assessment chart which type of intervention (active or placebo) he thought the participant had received. These codes will be later compared with the randomization codes.

Statistical methods: Statistical analysis will be used SPSS (Statistical Package for Social Sciences) v.19.0. Initially the Kolmogorov-Smirnov test will be performed. If the data are normal, parametric tests will be applied, if the distribution is non-normal, non-parametric tests will be used. It will be calculated from the effect size, by means of the difference between the means of the pre-intervention evaluation and the post-intervention evaluation. In all analyzes, a critical level of 5% (p <0.05) will be set.

Inclusion Criteria:

• primary complaint of chronic non-specific low back pain (more than 12 weeks);
• pain symptoms in the low back with a score ≥ 2/10 on the 0-10 Numerical Pain Rating Scale (12);
• aged 18-80;
• history of surgery in the abdominopelvic region for more than 6 months;
• history of visceral dysfunction (e.g., constipation and reflux); and
• no known or suspected serious spinal pathology (e.g., metastasis, inflammatory or infective diseases of the spine, causa equine syndrome, canal stenosis, spinal fracture).

Exclusion Criteria:

• no nerve root compromise evidenced by at least two of the following: (1) myotomal weakness, (2) dermatomal or widespread sensory loss, (3) hyporeflexia or hyperreflexia of the lower limb reflexes;
• no spinal surgery within the preceding 6 months;
• no vascular abnormality such as abdominal aortic aneurysms;
• not currently receiving chiropractic, osteopathic or other physical therapy;
• not pregnant or suspect being pregnant;
• not currently in an acute inflammatory phase of known gastrointestinal or urinary diseases (such as cholecystitis, renal calculi, peritonitis, appendicitis);
• not currently taking medications that significantly alter gut motility;
• not currently taking medications (such as oral corticosteroids) which are known to increase the risk of intestinal perforation);
• no known gastrointestinal disease that associates with a risk of intestinal perforation (e.g. Chron's disease, diverticular disease, peptic ulcer disease);
• not taking anti-platelet medications such as warfarin.

20 participants with chronic low back pain and visceral dysfunction

The adverse effects were collected before and after each session. A total of 5 weeks.

The patients were asked by the treating physiotherapist about adverse effects such as sore muscles, back pain and abdominal discomfort. The therapist took note on a blank paper corresponding to the participant identification number.

High dropout rate for the control group compromised statistical power; Unreliability of the placebo technique.

The evaluator will be blind as he will not be present during the intervention. As well as the care provider will not be present during the assessor activities.