Recent studies have reported that the application of thermal energy delivered through a bronchoscope (bronchial thermoplasty) impairs the ability of airways to narrow in response to methacholine. How such altered smooth muscle affects the response of airways to lung inflation may have important clinical implications, particularly as it relates to the abnormal response of asthmatic subjects to lung inflation and deep inspiration. The aim of this study was to examine whether bronchial thermoplasty affected airway distension with lung inflation in relaxed and contracted airways.