Review

Athletes such as skaters and skiers inhale large volumes of cold air during exercise and shift from nasal to mouth breathing. Endurance athletes, like cross-country ski-ers, perform at 80 % or more of their maximal oxygen consumption and have minute ventilations in excess of 100 l/min. Cold air is always dry, and endurance exercise results in loss of water and heat from the lower respira-tory tract. In addition, athletes can be exposed to indoor and outdoor pollutants during the competitive season and during all-year training. Hyperpnoea with cold dry air represents a signifi cant environmental stress to the airways. Winter athletes have a high prevalence of respiratory symptoms and airway hyper-responsiveness to methacholine and hyperpnoea. The acute effects of exercise in cold air are neutrophil infl ux as demon-strated in lavage fl uid and airway epithelial damage as demonstrated by bronchoscopy. Upregulation of pro-infl ammatory cytokines has been observed in horses. Chronic endurance training damages the epithelium of the small airways in mice. Airway infl ammation has been observed on bronchoscopy of cross-country ski-ers and in dogs after a 1100-mile endurance race in Alaska. Neutrophilic and lymphocytic infl ammation with remodelling is present in bronchial biopsies from skiers. Repeated peripheral airway hyperpnoea with dry air causes infl ammation and remodelling in dogs. As it is currently unknown if these airway changes are revers-ible upon cessation of exposure, preventive measures to diminish exposure of the lower airways to cold air should be instituted by all winter sports athletes