Exercise-Induced Laryngeal Obstruction (EILO)

Definition

Exercise-Induced Laryngeal Obstruction (EILO) is an inappropriate, transient narrowing of the larynx that occurs during high-intensity exercise and resolves rapidly once exercise stops. It is the exercise-triggered form of inducible laryngeal obstruction (ILO), the umbrella term agreed by the European Respiratory Society and European Laryngological Society for reversible upper-airway narrowing in response to a trigger.¹ The older labels vocal cord dysfunction, paradoxical vocal fold motion and exercise-induced laryngomalacia describe overlapping phenomena; the 2013 international consensus replaced them with the ILO nomenclature, which classifies obstruction by the level at which it occurs and by its trigger.²

Pathophysiology

At high ventilatory rates the pressure inside the upper airway falls sharply on each breath in. Normally the laryngeal muscles counteract this by actively widening the inlet. In EILO that opening fails, and structures are drawn inwards instead. Two patterns are recognised, and they frequently coexist:³

• Supraglottic obstruction — the tissues above the vocal folds (the aryepiglottic folds and arytenoid cartilages) collapse inwards as inspiratory flow rises. This is the more common pattern in adolescents and generally appears first as exercise intensifies.
• Glottic obstruction — the vocal folds themselves adduct, narrowing the airway at the level of the folds. This usually appears later in an exercise bout and may follow supraglottic collapse.

Because the obstruction is at the laryngeal inlet and not in the small airways, the difficulty is predominantly on breathing in, and it disappears within minutes of stopping — the larynx reopens as soon as ventilatory demand falls. This is a mechanical and neuromuscular control problem, not an inflammatory one, which is why anti-inflammatory and bronchodilator therapy does not resolve it.¹

Co-morbidities

EILO commonly sits alongside other conditions, and identifying them matters because they are treatable in their own right and can amplify symptoms: asthma and exercise-induced bronchoconstriction (which may be present as well as EILO, not instead of it), dysfunctional breathing, allergic rhinitis and post-nasal drip, gastro-oesophageal reflux and laryngopharyngeal reflux, chronic cough, and anxiety around performance and competition.⁴ Reflux and rhinitis in particular increase laryngeal irritability and are worth treating before concluding that breathing retraining has failed.

Prevalence

EILO affects an estimated 5–7% of adolescents and young adults in the general population, with a consistent female predominance.⁵ Among athletes and physically active young people investigated for unexplained exertional breathlessness, prevalence is much higher — around a third in some series — and EILO is a leading explanation for exercise symptoms that have not responded to asthma treatment.⁶ It is under-recognised rather than rare.

Causes and triggers

There is no single cause. Recognised contributors and triggers include:

• High-intensity exercise — symptoms appear close to peak effort, typically in the last third of a hard session, race or match.
• Cold, dry or polluted air, and chlorinated indoor pool air, which irritate the laryngeal mucosa.
• Upper-airway inflammation — rhinitis, recent viral infection, reflux.
• High competitive or performance pressure, which is an aggravator in some people but is not the cause of the condition and should not be presented as one.
• Anatomical predisposition — a relatively compliant supraglottis, which may explain the adolescent peak.³

Symptoms

• Difficulty breathing in, rather than out.
• Noisy breathing — stridor, a harsh high-pitched sound, often described by coaches or team-mates rather than by the athlete.
• Tightness felt at the throat or neck, not deep in the chest.
• A sense of the airway closing, choking or panic.
• Onset at or near maximum effort, with rapid recovery — usually within one to five minutes of stopping.
• Voice change, cough or throat clearing immediately afterwards.

How EILO differs from asthma

The two can coexist, so a confirmed diagnosis of asthma does not exclude EILO — and a negative bronchial provocation test does not exclude it either, because provocation testing does not detect laryngeal obstruction.⁷

Diagnosis

Why diagnosis matters

EILO is routinely misdiagnosed as difficult asthma. The consequences are real: years of escalating inhaled therapy that cannot work, avoidable side effects, withdrawal from sport, and in some cases emergency presentations for what is a self-limiting laryngeal event. Diagnostic delay of several years from first symptoms to correct diagnosis is common.⁶ Naming the condition accurately is itself part of the treatment.

How is it diagnosed?

The history does most of the work — inspiratory difficulty, throat-level tightness, onset at peak effort and fast recovery. But history alone cannot distinguish EILO reliably from other causes of exertional breathlessness, so objective testing is recommended wherever it is available.¹

Laryngoscopy during exercise

The reference standard is the continuous laryngoscopy exercise (CLE) test, in which a flexible laryngoscope is secured in place while the patient exercises to maximum on a treadmill or bike, so the larynx is watched directly at the moment symptoms occur.⁸ The obstruction is graded at supraglottic and glottic level using a standardised scoring system, which allows severity and treatment response to be compared over time.⁹ Resting laryngoscopy is normal in most people with EILO and cannot rule it out.

Lung function

Spirometry is normal between episodes. A truncated or flattened inspiratory limb on the flow–volume loop during symptoms is suggestive but is neither sensitive nor specific enough to diagnose EILO on its own. Exercise or eucapnic voluntary hyperpnoea challenge is used to identify or exclude co-existing exercise-induced bronchoconstriction rather than to diagnose EILO itself.¹⁰

Investigations for related conditions

Assessment for rhinitis, reflux, vocal pathology and dysfunctional breathing is part of the workup, because these are common, treatable, and will limit the response to laryngeal retraining if left alone.⁴

Management

Management and goals

The goals are to restore confident, full-effort exercise, to stop unnecessary asthma treatment where EILO is the sole diagnosis, and to give the person a reliable technique they can use the moment symptoms begin. Most people are managed non-surgically.¹

Treatment options

• Explanation and reassurance — understanding that the larynx is closing and will reopen, and that the episode is not dangerous, substantially reduces the panic component. This is a genuine intervention, not a preamble to one.
• Breathing retraining and laryngeal control therapy — the first-line treatment, delivered by a physiotherapist or speech pathologist.³
• Treatment of co-morbidities — rhinitis, reflux and any genuine asthma.
• Biofeedback with visual laryngoscopy during exercise, where available, so the person sees the larynx open as the technique is applied — effective in cases refractory to therapy alone.¹¹
• Surgery — reserved for severe, therapy-resistant supraglottic collapse.

Breathing techniques that help

• Nasal or pursed-lip inspiration early in exercise, to keep laryngeal pressures moderate and the inlet stable.
• Sniff–exhale and other rescue patterns deployed at the first sign of throat tightening rather than after full obstruction.
• Relaxed-throat breathing with a released jaw, tongue and neck, unloading the accessory muscles.
• Graded warm-up, so ventilation rises progressively instead of jumping to maximum.
• Rehearsal at intensity — the technique must be practised in training at the effort where symptoms happen, not only at rest, or it will not be available when needed.

Inspiratory muscle training

Inspiratory muscle training is used as an adjunct: resisted inspiration encourages an actively widened laryngeal inlet and a slower, deeper inspiratory pattern, and it gives a structured home programme between sessions.¹² Evidence is limited and it supplements laryngeal retraining rather than replacing it.

Surgery

Supraglottoplasty — trimming the collapsing supraglottic tissue — is considered only for severe supraglottic EILO confirmed on CLE testing that has not responded to therapy. In selected patients, it improves symptoms and exercise capacity.¹³ It has no role in glottic obstruction.

Identifying an episode

An EILO episode is recognised by its shape: it builds at high effort, is loudest on breathing in, and eases within a few minutes of slowing down. Symptoms that persist beyond that, or that come on after exercise finishes, point to something else — usually exercise-induced bronchoconstriction — and should be reassessed.

Action plan

1. Reduce intensity as soon as the throat tightens — slow down rather than stop dead.
2. Apply the rescue breathing pattern that was practised in training.
3. Breathe in through the nose, keeping the throat and jaw loose.
4. Expect the airway to open within a few minutes; do not add reliever inhaler if asthma has been excluded.
5. Resume at lower intensity once breathing settles.

Medications

Medications for EILO

There is no drug treatment for EILO itself. Medication is directed at the conditions that sit alongside it — intranasal corticosteroid for rhinitis, proton pump inhibitor therapy for reflux where confirmed, and inhaled corticosteroid for co-existing asthma. Inhaled ipratropium and other agents have been tried without a reliable evidence base.

Why reliever inhalers often do not help

A short-acting beta-agonist dilates the bronchi. EILO obstructs at the larynx, above them, so there is little for the drug to act on — one reason a poor reliever response in an athlete with exertional symptoms should prompt reassessment rather than dose escalation.⁷ Where exercise-induced bronchoconstriction is genuinely present as well, the reliever is still indicated for that component, alongside warm-up and environmental measures.¹⁰ Do not stop prescribed asthma treatment without discussing it with the prescriber first.

Living with EILO

Sport and training

EILO is not a reason to stop exercising, and avoidance makes matters worse by reducing fitness and increasing anticipatory anxiety. A structured warm-up, awareness of cold or dry air, and a rehearsed rescue technique allow most people to train and compete at full intensity.

School, work and coaches

People around the athlete need to know what an episode looks like, that it settles quickly, and that it is not an asthma attack. A brief written explanation for coaches, teachers or a workplace prevents well-meant but unhelpful responses — and prevents the athlete being pulled out of sport unnecessarily.

Confidence and anxiety

Anxiety commonly develops after repeated frightening episodes rather than causing them. Framing EILO as a mechanical problem of laryngeal control that responds to training addresses both the symptom and the fear. Where anxiety is prominent it is treated in its own right, not as a substitute for laryngeal therapy.

Sleep and general health

Symptoms are exercise-bound, so sleep is typically unaffected. Breathlessness at night or at rest suggests another diagnosis and warrants review.

Prognosis

The outlook is good. Most people improve substantially with explanation and breathing retraining, and many adolescents improve further with growth. The main determinants of a poor outcome are diagnostic delay — often several years, during which sport may be abandoned — untreated co-morbidity, and technique that has never been practised at the intensity where symptoms occur.¹⁴ Severe supraglottic collapse that persists despite good therapy has a surgical option with favourable results.¹³

Role of the physiotherapist

The physiotherapist is central to EILO management rather than adjunctive. They take the history that separates laryngeal from bronchial symptoms and refer for continuous laryngoscopy exercise testing where indicated, teach and progress laryngeal control and breathing retraining, rehearse the rescue pattern at true exercise intensity, apply inspiratory muscle training as an adjunct, screen for coexisting dysfunctional breathing, and rebuild confidence and training load.³ They also work with the medical team on whether asthma therapy is still warranted.¹²

Part 1 · References

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11. Olin JT, Clary MS, Fan EM, et al. Therapeutic laryngoscopy during exercise: a novel non-surgical therapy for refractory EILO. Eur Respir J 2017;50(2):1601395.
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13. Norlander K, Johansson H, Jansson C, Nordvall L, Nordang L. Surgical treatment is effective in severe cases of exercise-induced laryngeal obstruction: a follow-up study. Acta Otolaryngol 2015;135(11):1152–1159.
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References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.