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).