Knowledge
Breathlessness during hard exercise is often labelled asthma, but in many cases the cause sits in the larynx, not in the lungs. The two conditions call for entirely different treatment, so telling them apart matters.
Exercise-induced asthma (EIB) and exercise-induced laryngeal obstruction (EILO) both cause breathlessness in connection with physical exertion, and from the outside they can look very similar. The mechanisms are entirely different: asthma is a narrowing of the lower airways in the lungs, while EILO is a transient narrowing in the larynx, at the entrance to the airways. Asthma is treated with medication; EILO is managed primarily with breathing and laryngeal techniques. The two conditions can also coexist.
EILO stands for exercise-induced laryngeal obstruction. During hard exertion, the structures of the larynx narrow the airway opening, so it becomes harder to breathe. It typically presents at high intensity — often near maximal effort — with audible, laboured breathing in (stridor), a feeling that the throat is closing, and breathlessness that eases within minutes once you stop. EILO is common in adolescents and athletes and is one of the conditions most frequently mistaken for asthma.
Exercise-induced asthma (exercise-induced bronchoconstriction, EIB) is a transient narrowing of the lower airways triggered by exertion. Symptoms are cough, wheeze, chest tightness and breathlessness, typically during and especially in the minutes after exercise, subsiding over half an hour to an hour. Cold, dry or chlorinated air makes it worse, which is why it is common in endurance, winter and swimming sports. Correctly diagnosed, it usually responds well to asthma medication.
Read about exercise-induced asthma
No single symptom settles the question, but the pattern points in a direction. These are the typical differences:
Because the treatment differs. If EILO is mistaken for asthma, the result is often years of inhaled medication without effect, while the actual cause goes unaddressed. EILO is managed primarily with breathing and laryngeal techniques, guided by the correct diagnosis. Conversely, genuine exercise-induced asthma should be treated properly, so it does not limit your training. And because the two can coexist, a structured work-up looks at the whole picture rather than stopping at the first plausible answer.
Symptoms alone are unreliable, so the diagnosis is made objectively. Asthma is confirmed or ruled out with lung-function testing and, where needed, a bronchial provocation test: for athletes typically EVH (eucapnic voluntary hyperventilation) or an exercise challenge. The most reliable test for EILO is continuous laryngoscopy during exercise (CLE), where the larynx is observed while you exert yourself. The clinic will establish CLE in the near future. The choice of tests depends on your history, sport and symptom pattern.
Record a short audio or video clip of your breathing while you have symptoms, and note when they appear (during or after exercise), what you were doing, and how quickly they subside. That pattern is often the single most useful piece of information at the first consultation.
The clinic assesses exercise-related breathlessness with objective testing. EILO is one of its areas of special expertise. A referral from your GP is normally required; you can also be seen as a private or insurance patient. This page is general information and does not replace a medical assessment.