Enhancement of Exercise-Induced Asthma by Cold Air

TLDR

The study examined whether breathing cold air during exercise worsens bronchoconstriction in asthma patients. Participants performed exercise trials breathing ambient or subfreezing air, and pulmonary mechanics were measured before and after each session, with a separate rest trial to isolate cold‑air effects. Cold air during exercise markedly amplified bronchoconstriction, increasing residual volume by 158 % and reducing conductance and FEV1 by 85–100 %, whereas cold air alone at rest had minimal effect, confirming that exercise and cold air synergistically trigger asthma attacks.

Abstract

To study the possibility that the inhalation of cold air accentuates the bronchoconstrictor response to exercise in asthma, eight subjects exercised while breathing air at ambient or subfreezing temperatures. On a separate day, cold air was breathed at rest so as to isolate the effects of this stimulus. Pulmonary mechanics were measured before and after each experiment. In all subjects acute bronchoconstriction followed the control exercise challenge. With cold-air breathing, however, the magnitude of the response was markedly enhanced. Residual volume increased 158 per cent more than it did previously, and specific conductance and one-second forced expiratory volumes changed an additional 85 and 100 per cent, respectively. The effects of cold air at rest were very small. The results demonstrate a positive interaction of two common naturally occurring stimuli in the induction of asthmatic attacks, and constitute objective verification of a frequent clinical complaint.