Respiratory muscle strength
Respiratory muscle strength was assessed by measuring the maximal inspiratory (MIP) and expiratory pressures (MEP). The test was performed using a digital manovacuometer (MVD 300-U, Globalmed, RS, Brazil). The device was connected to a tube coupled to a sterilized filter that was attached to a mouthpiece. The assessments were performed in a seated position while the subject wore a nose clip. The MIP was assessed after maximal expiration near the residual volume, while the MEP was assessed after maximal inspiration near the total lung capacity (16). Both measurements were performed with maximum effort and sustained for at least 1 second. The number of repetitions, interval time, and best value from the acceptable trials were used for analysis, as in the assessment of peripheral muscle strength. The respiratory muscle strength values are expressed in cmH2O and the percentage of the predicted values. The predicted values were obtained from a Brazil population and stratified by sex, age, height, and weight (17).