Humidity influences exercise capacity in subjects with Exercise- Induced Broncho - Constriction (EIB)

Abstract

The primary aim of the present study was to examine the effect of changing the humidity of the environmental air upon exercise capacity measured by peak oxygen uptake (V • O 2 peak ), peak ventilation (V • E peak ) and peak running speed (V • peak ) and secondarily to assess the influence of environmental humidity upon EIB in subjects suffering from EIB. Twenty subjects (10-45 years old, male/female:13/7) with diagnosed EIB performed exercise testing under standardised, regular environmental conditions, 20.2 o C (±1.1) and 40 per cent (±3.3) relative humidity [mean (±sd)] and under standardised humid environmental conditions, 19.9 o C (±1.0) and 95 per cent (±1.7) relative humidity in random order on separate days. Lung function was measured before and 1, 3, 6, 10 and 15min after exercise. Heart rate (HR), oxygen uptake (V • O 2 ), respiratory gas exchange ratio (RER), breathing frequency (BF) and minute ventilation (V • E) were measured during exercise. The results were indentified that V • O 2 peak and V • peak increased significantly from 40 per cent to 95 per cent relative humidity of the environmental air, 4.5 per cent and 5.9 per cent, respectively (P=0.001). HR peak increased significantly in the humid environment, while BF peak decreased significantly. The conclusion that exercises capacity (V • O 2 peak and V • peak ) markedly improved during exercise in humid air in subjects with EIB, whereas EIB was reduced to the half.