Influence of smoking on respiratory muscle strength in elderly

Abstract

This study evaluated the influence of smoking on respiratory muscle strength (maximal inspiratory and maximal expiratory pressures) in physically independent elderly compared to nonsmokers. We selected 120 aged people equal or above 60 years-old divided into two groups, according to the World Health Organization criteria: Smokers Group, including 106 individuals, and Nonsmokers Group, with 14. A structured questionnaire was applied to collect demographic data. For respiratory muscle strength evaluation, a GERAR® analog manovacuometer with a range of -300 to +300 cmH2O was used. Student's t-test was used to evaluate the difference between means, and Pearson's correlation coefficient (r²) to analyze associations. The Smokers Group presented lower maximum inspiratory pressure with a significant difference (p<0.0001). There was no significant difference in the maximum expiratory pressure. It was observed that the body mass index was also significantly lower in smokers (p<0.0001), however no positive correlation with inspiratory muscle strength was found. These results suggest that smoking is related with reduction of the inspiratory muscle strength, and that although it does not present a positive correlation with such decreased muscle strength, body mass index was also reduced in such individuals.