Intensive physical training reduces the airway response to methacholine in asthmatics

We previously reported that responsiveness to methacholine (Mch) in the absence of deep inspiration (DI) can decrease in healthy subjects after exercise training. We assessed whether exercise training also reduces airway responsiveness in asthmatics. Nine patients (M/F: 3/6; mean age±SD: 24±2 yrs) with mild asthma (FEV1 100±7.4% pred, FEV1/VC 90±6.5%) underwent single dose Mch bronchoprovocations in the absence of DI at baseline (Visit 1) and after training (6 hours/week of submaximal rowing) for 5 (Visit 2) and 10 (Visit 3) consecutive weeks. The single dose Mch was established at Visit 1 as the dose able to induce at least 15% reduction in IVC. The same single dose Mch was administered to each subject at every subsequent challenge. Five asthmatics (M/F: 1/4; mean age±SD: 26±3 yrs) with similar baseline lung function (FEV1: 102±7.0% pred, and FEV1/VC: 83±6.0%; p=0.57 and p=0.06, respectively) not participating to the training program, served as controls (single-dose, no-DI, Mch tests at baseline and 10 weeks). In the trained group, the Mch-induced reduction in IVC from baseline was 22±10% at Visit 1, 13±11% at Visit 2, 11±8% at Visit 3 (ANOVA for repeated measures: p=0.028). Mch responsiveness at Visit 2 and 3 was reduced compared to baseline (p=0.03 and p=0.01, respectively). The reduction in responsiveness induced by training was of magnitude similar to that previously obtained in healthy subjects. In controls, Mch-induced reduction in IVC at baseline was similar to that of the trained asthmatics (21±20%), and remained unchanged after 10 weeks (29±14%, p= 0.28). This pilot study indicates that physical training is capable of reducing airway responsiveness in mild asthmatics.