title: Exercise tolerance breathing a low density gas mixture, 35 per cent oxygen and air in patients with chronic obstructive bronchitis.
mesh_terms: D000368:Aged; D000403:Airway Resistance; D001827:Body Height; D001835:Body Weight; D001991:Bronchitis / Q000503:physiopathology*; D002908:Chronic Disease; D006339:Heart Rate; D006371:Helium; D006801:Humans; D008297:Male; D008875:Middle Aged; D009584:Nitrogen; D010100:Oxygen; D005082:Physical Exertion; D012119:Respiration; D012143:Respiratory Physiological Phenomena; D013147:Spirometry
chemical_list: D006371:Helium; D009584:Nitrogen; D010100:Oxygen