Exercise-Induced Bronchoconstriction

Transient airway narrowing during or after exercise, defined by a <strong>fall in FEV₁ of 10% or more</strong> after a standardised challenge. It occurs with or without asthma, so "exercise-induced asthma" is discouraged.

Mechanism and risk

High minute ventilation of cold, dry air dries and cools the airway, triggering mediator release (osmotic and thermal theories).

Prevalence: up to 30 to 50% in elite endurance athletes, versus 7 to 10% in the general population.
Sports: cross-country skiing, swimming (chlorine), running, cycling, ice hockey, figure skating
Environment: cold dry air (strongest trigger), pollen, pollution
Athlete: atopy, asthma, high training volume. Beta-blockers can worsen it.

Presentation

Cough, the commonest symptom, especially after exercise
Wheeze peaking 5 to 10 minutes after exercise, resolving in 30 to 60 minutes
Chest tightness, breathlessness out of proportion to workload
Refractory period: a second bout within 1 to 2 hours provokes less bronchoconstriction
Unexplained performance decline, especially in the cold

Mimic: EILO

	EIB	EILO (laryngeal obstruction)
Sound	Wheeze	Stridor
Timing	Peaks after exercise	During maximal exertion
Resolution	30 to 60 minutes	Quickly on stopping
Bronchodilator	Responds	No response

EILO needs laryngoscopy during exercise. Misdiagnosis means years of ineffective inhaler use.

Diagnosis

Do not diagnose on symptoms alone. They are non-specific and correlate poorly with objective testing. Objective testing is mandatory, also to justify a TUE if needed.

Eucapnic voluntary hyperpnoea (EVH): preferred for elite athletes
Exercise challenge (10% or greater FEV₁ fall), mannitol or methacholine challenge
Spirometry with reversibility to confirm asthma

Management

Non-drug

thorough warm-up (induces the refractory period), nose breathing or a scarf or mask in cold air, avoiding allergens and pollution.

Agent	Role
Inhaled SABA (salbutamol)	15 minutes before exercise. First-line prevention and relief
Inhaled corticosteroid	Cornerstone of control in EIB with asthma
ICS plus LABA	Persistent symptoms
Leukotriene antagonist	Adjunct, useful to avoid daily ICS
Mast cell stabiliser, antihistamine, ipratropium	Selected cases

The anti-doping trap

Beta-2 agonists are prohibited by every route except inhalation. Inhaled salbutamol up to 1600 µg/24 h needs no TUE. Inhalers containing terbutaline, fenoterol, reproterol or higenamine are prohibited. Check each inhaler against the current WADA list. See the Doping article.

References

Hostrup et al., Scand J Med Sci Sports 2024, doi:10.1111/sms.14358
Goldin & Bruner, StatPearls 2025, NBK557554
Cureus 2022, doi:10.7759/cureus.20898

Medical disclaimer: this article is general information, not personal medical advice. Always consult a qualified doctor about your own situation.