OBJECTIVE: to determine whether preoperative inspiratory muscle training (IMT) is able to attenuate the impact of surgical trauma on the respiratory muscle strength, in the lung volumes and diaphragmatic excursion in obese women undergoing open bariatric surgery.

Therefore, the hypothesis of the present study was that preoperative IMT is able to attenuate the negative effects of surgical trauma on the respiratory muscle strength, in the lung volumes and diaphragmatic excursion, thus reducing the risk of PPC, in obese patients undergoing open bariatric surgery.

DESIGN: Randomized controlled trial. SETTING: Meridional Hospital, Cariacica/ES, Brazil. SUBJECTS: Thirty-two obese women undergoing elective open bariatric surgery were randomly assigned to receive preoperative inspiratory muscle training (IMT group) or usual care (control group).

MAIN MEASURES: Respiratory muscle strength (maximal inspiratory pressure - MIP and maximal expiratory pressure - MEP), lung volumes and diaphragmatic excursion.

Inclusion Criteria:

• Female,
• Over 18 years of age,
• No smoking or respiratory disease.

Exclusion Criteria:

• Patients who refused to participate in the steps of the research protocol,
• Patients with a history of prior abdominal surgery,
• Patients who were unable to understand and perform the tests properly
• Patients who refused to sign the Informed Consent Term.