Reference values for lung function tests. II. Maximal respiratory pressures and voluntary ventilation

The strength of the respiratory muscles can be evaluated from static measur ements (maximal inspiratory and expiratory pressures, MIP and MEP) or infer red from dynamic maneuvers (maximal voluntary ventilation, MW). Although th ese data could be suitable for a number of clinical and research applicatio ns, no previous studies have provided reference values for such tests using a healthy, randomly selected sample of the adult Brazilian population. Wit h this main purpose, we prospectively evaluated 100 non-smoking subjects (5 0 males and 50 females), 20 to 80 years old, selected from more than 8,000 individuals. Gender-specific linear prediction equations for MIP, MEP and M W were developed by multiple regression analysis: age and, secondarily, ant hropometric measurements explained up to 56% of the variability of the depe ndent variables. The most cited previous studies using either Caucasian or non-Caucasian samples systematically underestimated the observed values of MIP (P<0.05). Interestingly, the self-reported level of regular physical ac tivity and maximum aerobic power correlates strongly with both respiratory and peripheral muscular strength (knee extensor peak torque) (P<0.01). Our results, therefore, provide a new frame of reference to evaluate the normal cy of some useful indexes of respiratory muscle strength in Brazilian males and females aged 20 to 80.