Physical inactivity accentuates impairment of pulmonary mechanics in persistent moderate asthmatics: involvement of nitric oxide

Asthma is a chronic inflammatory disease of the airways, resulting in worse quality of life. There are evidences that physical activity improves quality of life and lung function of asthmatic patients, but some aspects, such as lung mechanics, has never been evaluated. Thus, we investigated the impact of physical inactivity on pulmonary function and mechanics of asthmatic patients. Twenty asthmatic (persistent moderate) individuals were classified according to GINA criteria and included in the study and then, stratified into active or inactive, according to the International Physical Activity Questionnaire: Ten physically active (38.22±14.64 years old) and 10 physically inactive (31.83±8.45 years old). Lung function was assessed by spirometry and lung mechanics by impulse oscillometry, both using MasterScreen (Jaeger, Germany) and exhaled nitric oxide by NoBreath monitor (Bedfont Scientific, UK). The results showed no difference in lung function FVC, FEV%, FEV1, FEV1% and FEV1/FVC (p>0.05). However, inactive asthmatics showed higher impedance of the respiratory system (Z5Hz, p<0.01), increased resistance of the whole respiratory system (R5Hz, p<0.01), resistance of proximal airways (R20Hz, p<0.01) and of distal airways (R5-R20Hz, p<0.01). In addition, the reactance of the lung tissue (X5Hz, p<0.01) was lower in physically inactive asthmatic patients. Furthermore, exhaled nitric oxide levels were higher in inactive asthmatic compared to active asthmatic (27,44±16,91 x 19±2,12 ppb; p<0.04). So, we conclude that physical inactivity accentuates the impairment of pulmonary mechanics in asthmatic patients, presenting an involvement of nitric oxide.