Humidity influences exercise capacity in subjects with exercise-induced bronchoconstriction (EIB).

Area of Science:

• Environmental Physiology
• Respiratory Medicine
• Sports Science

Background:

• Exercise-induced bronchoconstriction (EIB) is exacerbated by cold, dry air and ameliorated by humid air in asthma patients.
• Limited research exists on the impact of environmental humidity on exercise capacity in individuals with EIB.

Purpose of the Study:

• To investigate the effect of varying environmental humidity on exercise capacity, measured by peak oxygen uptake (V O2 peak), peak ventilation (V Epeak), and peak running speed (V peak).
• To evaluate the influence of environmental humidity on EIB severity in subjects diagnosed with EIB.

Main Methods:

• Twenty subjects (10-45 years) with diagnosed EIB underwent standardized exercise testing in both regular (20.2°C, 40% humidity) and humid (19.9°C, 95% humidity) conditions, in random order.
• Lung function (FEV1, FEF50) was assessed pre- and post-exercise (1-15 min).
• Cardiorespiratory parameters including heart rate (HR), V O2, respiratory gas exchange ratio (RER), breathing frequency (BF), and V E were measured during exercise.

Main Results:

• Exercise capacity significantly improved in humid air: V O2 peak increased by 4.5% and V peak by 5.9% (P=0.001).
• Peak heart rate (HRpeak) increased, while peak breathing frequency (BFpeak) decreased in humid conditions; RERpeak and V Epeak showed no significant changes.
• Post-exercise EIB, indicated by reductions in FEV1 (DeltaFEV1) and FEF50 (DeltaFEF50), was significantly reduced by half in humid air compared to regular conditions (P<0.001).

Conclusions:

• Environmental humidity significantly impacts exercise performance and EIB in individuals with asthma.
• Exercising in humid air markedly enhances exercise capacity (V O2 peak, V peak) and substantially reduces EIB severity.