Lung function after marathon running at warm and cold ambient temperatures.

using maximal expiratory flow-volume curves we studied the effects of endurance exercise on lung function in 46 and 41 runners before and after completion of a marathon race (42.2 km) at different ambient temperatures. There was a significant decrease (-3.9%; -5.9%) in the post-race forced vital capacity in runners at each marathon. The mean values for forced expiratory volume in one second did not change. Post-race peak flow at 50% of forced vital capacity were significantly decreased in runners participating in subfreezing conditions (-2 degrees C to -4 degrees C), but were unchanged when the ambient temperature was above freezing. These data demonstrated that healthy persons may develop bronchoconstriction during endurance exercise in subfreezing temperatures. The decrement in forced vital capacity noted in marathon runners competing at above freezing temperatures may be related to fuel metabolism and running performance.