Effects of exercise training on airway responsiveness and airway cells in healthy subjects

Abstract

Airway responsiveness to methacholine (Mch) in the absence of deep inspirations (DIs) is lower in athletes compared with sedentary individuals. In this prospective study, we tested the hypothesis that a training exercise program reduces the bronchoconstrictive effect of Mch. Ten healthy sedentary subjects (M/F: 3/7; mean + or - SD age: 22 + or - 3 yr) entered a 10-wk indoor rowing exercise program on rowing ergometer and underwent Mch bronchoprovocation in the absence of DIs at baseline, at weeks 5 and 10, as well as 4-6 wk after the training program was completed. Exercise-induced changes on airway cells and markers of airway inflammation were also assessed by sputum induction and venous blood samples. Mean power output during the 1,000 m test was 169 + or - 49 W/stroke at baseline, 174 + or - 49 W/stroke at 5 wk, and 200 + or - 60 W/stroke at 10 wk of training (P < 0.05). The median Mch dose used at baseline was 50 mg/ml (range 25-75 mg/ml) and remained constant per study design. At the pretraining evaluation, the percent reduction in the primary outcome, the inspiratory vital capacity (IVC) after inhalation of Mch in the absence of DIs was 31 +/- 13%; at week 5, the Mch-induced reduction in IVC was 22 + or - 19%, P = 0.01, and it further decreased to 15 + or - 11% at week 10 (P = 0.0008). The percent fall in IVC 4-6 wk after the end of training was 15 + or - 11% (P = 0.87 vs. end of training). Changes in airway cells were not associated with changes in airway responsiveness. Our data show that a course of exercise training can attenuate airway responsiveness against Mch inhaled in the absence of DIs in healthy subjects and suggest that a sedentary lifestyle may favor development of airways hyperresponsiveness.

Ventilation and Respiratory Mechanics

“…Well-trained athletes exhibit lower airway responsiveness to inhaled methacholine than individuals who do not exercise vigorously in their daily life (465). Moreover, short-term (5-10 weeks) aerobic exercise substantially reduces the bronchoconstrictive effect of inhaled methacholine in healthy subjects (466). These findings are consistent with epidemiological research suggesting a protective effect of physical activity on airway responsiveness (471).…”

Advances in asthma pathophysiology: stepping forward from the Maurizio Vignola experience

“…Subsequent studies in healthy runners showed that trained subjects were less responsive to single-dose methacholine inhaled in the absence of deep breaths [78], suggesting a positive effect of repeated airway smooth muscle stretching during exercise hyperpnoea. Moreover, healthy sedentary subjects showed decreased bronchial responsiveness after 12 weeks of training [79], and the same effect occurred in sedentary subjects with mild asthma undergoing the same training protocol [80]. Similar results of decreased bronchial responsiveness have been recently reported after application of continuous positive airway pressure (CPAP) during sleep for a week in asthmatic patients free from sleep disordered breathing [81].…”

Effects of Exercise on the Airways

“…Following this cross-sectional study, we longitudinally tested the effects of training in a group of healthy sedentary subjects undergoing intensive rowing training for 3 months. A significant reduction in the degree of bronchial reactivity in the absence of deep breaths was recorded during and at the end of the study (Scichilone et al, 2010). This observation shed new light in the field of bronchial hyperreactivity, since it indicates a significant effect of regular intensive exercise.…”

“…However, airway cell counts were similar in EIB+ and EIB-athletes and did not correlate with concentration of mediators in sputum supernatants (Parsons et al, 2008). Our study on the effects of training in non-asthmatic subjects found that changes in airway cells and in the response to methacholine in the absence of deep inhalations showed different time courses (Scichilone et al, 2010). The picture can be further complicated by interactions between airway epithelial cells and smooth muscle cells, as suggested by a study showing that hyperosmotic stimuli induce epithelial dependent relaxation in the guinea pig trachea in vitro (Munakata et al, 1988).…”

“…A large number of asthmatic elite athletes participate to international top-level competitions, and guidelines regarding management of asthmatic athletes (Fitch et al, 2008) and rules on the use of anti-asthmatic drugs have been issued (World Anti-Doping Agency, WADA, Oct. 18 2010 report). However, exercise is a powerful physiologic stimulus for bronchodilatation, and some reports underlined that exercise training may actually downmodulate bronchial reactivity in normal subjects (Scichilone et al, 2005(Scichilone et al, , 2010, asthmatic children (Bonsignore et al, 2008) and animal models of asthma (Hewitt et al, 2010). This chapter will summarize the changes induced by acute exercise and training in bronchial reactivity and airway cells in both humans and animal models.…”