Exercise-induced bronchodilation is not different in healthy males and females.

Abstract

Exercise-induced bronchodilation (EIBD) is the dilation of the airways that occurs during whole-body dynamic exercise. Females have greater β2-adrenergic receptor activity in the peripheral vasculature which accentuates vasodilation, but it is unknown if this translates to the airways. EIBD can be quantified by performing maximal expiratory maneuvers before and immediately after exercise; however, the assessment is impacted by thoracic gas compression. Accordingly, we sought to determine if there are sex differences in the extent of EIBD. Twenty-two healthy adults (n=11 female) performed multiple forced expiratory maneuvers in a custom-designed volume-displacement body plethysmograph, before and after incremental cycle exercise to volitional exhaustion. The customized body plethysmograph allows for simultaneous assessment of compressed and compression-free flow-volume loops. During exercise, inspired air was warmed (24±0.7°C) and humidified (94±6%) and post-exercise pulmonary function was completed <10 minutes after exercise cessation. Males had a greater maximal oxygen uptake than females (51±7 vs. 42±6 ml kg^-1min^-1, p <0.01). Using compressed flow-volume loops, forced expiratory volume in 1 sec was increased following exercise in males (5.03±0.58 vs. 4.80±0.63 L, p<0.01) and females (3.96±0.32 vs. 3.81±0.31 L, p<0.01), but the relative change from baseline was not different between the sexes (p=0.39). Likewise, the relative change in mid expiratory flows was not different between sexes (p=0.77). Using compression-free flow-volume loops, bronchodilation was evident using mid flows in both sexes. In conclusion, the extent of EIBD is not different between the sexes, but the use of compression free flow-volume curves only shows EIBD for mid flows in both sexes similarly.