Respiratory muscle strength was evaluated always by the same evaluator (physiotherapist), who presented over a year of previous experience performing the test and who was also trained and supervised by the principal investigator of the study. The test was evaluated using a previously calibrated digital manovacuometer (MVD 300, Globalmed, Porto Alegre, Brazil) with a variation of −300 to +300cm H2O. The instrument was connected to a silicone tube, coupled to an isolating filter and to a connector with an inner diameter of approximately 2.5cm, which was connected to a mouthpiece. The flattish, semi-rigid mouthpiece had an orifice, with a diameter of approximately 2mm to prevent an increase in intra-oral pressure generated by the contraction of the oral cavity muscles.4 Before measuring the respiratory pressures, the technician demonstrated and gave detailed guidance regarding the maneuvers to be performed.