[The effect of aging on respiratory muscle function].

To elucidate the effect of aging on respiratory muscle function, the authors performed respiratory muscle function tests in 116 normal subjects. Respiratory muscle function was evaluated with maximal expiratory mouth pressure at the TLC level (PEmax) and maximal inspiratory mouth pressure at the RV level (PImax). PEmax and PImax in both sexes showed significant correlations with age. PEmax in males was significantly higher than that in females (123.6 +/- 29.7 cmH2O and 79.0 +/- 21.1 cmH2O, p less than 0.01, respectively). PImax in males was also significantly higher than that in females (98.4 +/- 26.0 cmH2O and 71.9 +/- 26.4 cmH2O, p less than 0.01, respectively). PEmax correlated significantly with TLC, and PImax showed a significant inverse correlation with RV/TLC. Furthermore, there was a significant inverse correlation between RV/TLC and age. Our data suggest that inspiratory muscle weakness in aging may be responsible for the increase in RV/TLC.