Exercise performance in marathon runners with airway obstruction.

While evaluating lung function prior to four long-distance races (20-100 km), we found that nine of 127 marathon runners (7.1%) had airway obstruction (mean FEV1/FVC, 63.3%). Since obstruction to air flow may limit exercise performance, we compared selected cardiorespiratory parameters during exercise on a cycle ergometer in runners with airway obstruction (RAO), nine non-athletic control subjects (CON), and nine marathon runners with normal lung function (RNL). As the chemical drive to breath affects exercise hyperpnea, the ventilatory responses to hypercapnia and hypoxia were measured. All RAO were males with a mean age of 35.6 yr (range of 20-44 yr). Eight of nine RAO had a significant increase in flow rates after inhalation of isoproterenol. In the RAO and CON groups exercise ventilation was similar when oxygen consumption (VO2) was less than 2.0 l/min; as VO2 exceeded this level, significantly greater ventilation was required by the RAO. Carbon dioxide production was highest in RAO, intermediate in CON, and lowest in RNL. There was no significant difference in the mean ventilatory responses among CON, RAO, and RNL. Despite pulmonary dysfunction, the RAO achieved moderate-to-high levels of exercise performance.