title: Effect of carbon monoxide on maximal treadmill exercise. A study in normal persons.
abstract: The effect of breathing 100 ppm of carbon monoxide versus compressed, purified air for 1 h on maximal treadmill exericse was studied (double-blind crossover design) in 10 middle-aged, healthy nonsmokers. The mean venous carboxyhemoglobin level significantly increased from 1.67% to 3.95%  after breathing carbon monoxide (P less than 0.001) and significantly decreased from 1.63% to 1.30% after breathing compressed, purified air (P less than 0.001). The mean exercise time until exhaustion significantly decreased from 697.7 to 662.7 s after breathing carbon monoxide (P less than 0.001) and insignificantly increased from 694.9 s to 703.4 s after breathing compressed, purified air. Ischemic S-T segment depression larger than or equal to 1.0 mm after exercise occurred in 1 of 10 subjects after exercise following carbon monoxide inhalation. Increased carboxyhemoglobin levels of the magnitude encountered after smoking or heavy atmospheric pollution impair exercise performance in normal persons.
mesh_terms: D000388:Air; D001794:Blood Pressure / Q000187:drug effects; D002248:Carbon Monoxide / Q000633:toxicity*; D002263:Carboxyhemoglobin / Q000032:analysis*; D002986:Clinical Trials as Topic; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors
chemical_list: D006454:Hemoglobins; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin