The relevance of this study is given by the feasibility to assess the effect of an intervention program based on the functionality and trunk neuromuscular activity and postural control in pregnant women with low back pain. 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 two intervention methods using the main biological outcomes related to trunk segment function.

For this study, a proposal of a 6-week intervention program will be carried out with lumbar stabilization exercises and clinical orientations, on 20 low back pregnant patients recruited by convenience and voluntaries from the community. Before intervention, all participantes will be evaluated by: electromoyography during three exercises, balance, and clinical outcomes such as pain, disability and psychological factors. All baseline testing and evaluation will be performed by a blinded evaluator to the study intervention.

Afterwards, the participants will be randomized in two groups by a blinded evaluator (people not enroled to study): G1: exercises for lumbar stabilization; and G2: conventional therapy.

The intervention will follow six weeks, with 50 minutes of duration each session of therapy including measurement of blood pressure, heart rate and the Visual Analogue Scale (VAS) before and after each session, and the perception of exercise intensity monitored by Borg Scale. Within this proposal, the exercise sessions will be twice a week, lasting 40 minutes each, and followed by 10 minutes of theoretical orientation. The intervention will follow the CONSORT recommendations for randomized controlled trials. The intervention will start in: G1 (n=10), which will perform therapy with specific exercises for lumbar stabilization including the Swiss ball as therapeutic resource; while G2 (n=10, control group) will perform conventional therapy including stretching of lower limbs and trunk. The participants will not be blind to the study due to the characteristic of the exercises that often reflect to the improvement of the symptoms. In case of eventual losses, the intention-to-treat method will be used for the analyses.

After the intervention, all groups will be invited to come back to the laboratory to proceed the same evaluation from baseline (trunk activation during three exercises, balance, and clinical outcomes) For the analysis two-way ANOVA with repeated measures will be performed to compare the effects of the intervention (two groups) and times (baseline vs. end 6-weeks measurement)the effects of interaction (Groups x Times).

The inclusion criteria were:

• Have between 19-29 weeks of pregnancy;
• Have performed prenatal clinical monitoring;
• Have chronic low back pain (> 3 months) without irradiation for knees.
• Not being under medication or physical therapy treatment for low back pain in the last three months;
• To be able to perform physical activity consistent to the pregnancy;
• To present normal conditions of responsiveness, cognition and speaking;
• To be voluntary.

The exclusion criteria were:

• Signs or symptoms of other pathology including coexisting pathology, a recent history (within 3 months) of surgery in the locomotor system;
• Respiratory, neurological or cardiovascular diseases.
• Several musculoskeletal disorders.
• Limitations for physical exercise.
• Allergic reaction to adhesive tape,