Purpose Mountain ultra-marathons (MUM) impose multiple stressors on pulmonary function inducing risk of airway epithelial damage. This study aimed to assess the magnitude of pulmonary function changes and the associated risks of airway damage induced by such a race. Methods Thirteen volunteers completed the MUM (330 km, 24,000 m elevation gain). Pulmonary function was assessed using standardized procedures before (pre-) and wi...