Effects of a heat and moisture exchanger on respiratory function and symptoms post-cold air exercise

Exercise at temperatures below -15°C induces drying and cooling of lung airways which causes exercise-induced bronchoconstriction (EIB) and respiratory symptoms, especially in winter sport athletes. The objective of this study was to evaluate whether a heat and moisture exchanger (HME) worn during intense cold air exercise improves lung function and reduces respiratory symptoms in healthy winter sport athletes.

Seven active males and six active females (maximum oxygen uptake 61.9 ± 6.9 and 52.2 ± 5.3 mL/kg/min), all active or former winter sport athletes, completed running trials with and without HME in random order on 2 days in an environmental chamber (-20°C temperature, humidity 46.2%). Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁ ), forced expiratory flow at 25%-75% (FEF_25%-75% ), and FEF at 50% (FEF_50% ) were measured pre- and post-exercise (3, 6, 10, 15, and 20 minutes). Respiratory symptoms were reported after exercise.

Significant interaction effects were observed for FEV₁ and FEF_25%-75% . Mean decrease of FVC (-5.9%, P ≤ .001) and FEV₁ (-4.2%, P = .003) was largest 3 minutes post-exercise without HME. There was an increase of FEV₁ , FEF_25%-75% , and FEF_50% post-exercise compared to pre-exercise with HME. More respiratory symptoms overall were reported without HME (P = .046).

Intense cold air exercise likely causes transient acute bronchoconstriction and symptoms of cough in individuals participating in winter sports. However, this study finds that the application of an HME during intense cold air exercise improves lung function and reduces prevalence of EIB-associated symptoms compared to unprotected intense cold air exercise.