Exercise induced bronchial lability in normal men and women--a comparison.

Normal male (n = 29) and female (n = 39) medical students with a mean age of 19.2 years who were nonsmokers, with no personal history of allergy were studied. The bronchial lability was assessed from peak expiratory flows and forced expiratory spirograms taken before, during and upto 45 minutes after a standard exercise using the Harvard steps. Women had a significantly lower (P < .001) resting FVC, FEV1, FEF 25-75% and PEF as compared to men. Although the exercise lability index was not significantly different in men and women, the latter showed a greater percent increase (P < .02) and a lesser percent decrease (P < .02) of PEF during and after the exercise respectively. They also showed a significantly (P < .005) faster recovery to normal. These results suggest that airway dynamics may be better in women than in men. This could account for the lower incidence and morbidity from respiratory allergic disease seen in women as compared to men.