Exercise-Induced Laryngeal Obstruction

The larynx sits at the top of the airway and acts as a valve. During normal breathing in, and especially during the hard, fast breathing of exercise, the vocal folds and the structures above them open widely to let air pass with as little resistance as possible. In EILO this fails at high effort: instead of opening, laryngeal structures move inwards and narrow the airway just when maximal airflow is needed.

The narrowing is described by where it happens. Glottic obstruction is inward movement of the true vocal folds themselves, while supraglottic obstruction is inward collapse of the structures just above the folds, the arytenoid region and aryepiglottic folds, and the supraglottic pattern is common in exercise.

The mechanism is not fully understood, but the very high airflow and the strong negative pressure generated inside the airway during forceful inspiration appear to draw these mobile structures inwards, helped along in some athletes by laryngeal irritability from reflux or post-nasal drip.

Two features follow directly. The obstruction appears at or near peak effort, when airflow and negative pressure are greatest, and it resolves within seconds to minutes of stopping, because the driving forces disappear the moment hard breathing stops. This rapid on and off pattern is central to recognising it.

The story of EILO is distinctive once it is known. The athlete struggles to get air in at high intensity, feels tightness in the throat or neck rather than the chest, and often makes a harsh noise on breathing in, sometimes described as a wheeze but really a stridor. Symptoms come on at peak effort and then settle remarkably quickly once the athlete slows or stops, often within a minute or two. Inhaled relievers make no real difference, and the voice may change briefly around an episode.

This pattern is what separates EILO from EIB, and holding the two side by side is the most useful clinical exercise. EIB tends to cause an expiratory wheeze and chest tightness that build in the minutes after stopping and ease over a longer period, and it responds to inhalers. EILO causes inspiratory difficulty and throat tightness at peak effort that vanish quickly and do not respond to inhalers. Anxiety can accompany EILO, but it is a genuine physical laryngeal event and not simply a nervous habit. Cardiac disease must always be considered where there is chest pain, palpitations or fainting.

Because the obstruction only happens during exercise, examining the larynx at rest is usually normal and does not rule EILO out. The definitive investigation is continuous laryngoscopy during exercise, in which a thin flexible laryngoscope is held in place while the athlete exercises to peak intensity, ideally hard enough to bring on their symptoms, so the larynx can be watched directly and the obstruction seen, located as glottic or supraglottic, and graded as it occurs. This test both confirms the diagnosis and shows which pattern is present, which guides treatment.

Other tests play a supporting role. Lung function may show flattening or truncation of the inspiratory limb of the flow-volume loop while the athlete is symptomatic, though resting loops are frequently normal. Spirometry and a challenge test are still worthwhile, because EILO and asthma or EIB can coexist, and finding one does not exclude the other. Above all, a careful history that captures the inspiratory, throat-level, peak-effort, rapidly resolving and inhaler-unresponsive pattern is what should prompt referral for the laryngoscopy that settles the diagnosis.

The good news is that EILO usually responds well to non-drug treatment, and inhalers are not the answer unless asthma coexists. The foundation is education, since simply understanding that this is a recognised, mechanical and treatable laryngeal event reduces fear and, for some athletes, is itself part of the cure. The cornerstone of active treatment is breathing retraining, delivered by a speech and language therapist or a respiratory physiotherapist with an interest in the larynx. Athletes are taught specific techniques, such as relaxed-throat and controlled breathing patterns and particular inspiratory manoeuvres, to keep the larynx open and to abort an episode as effort rises, and these are practised until they can be used during competition.

Contributing factors are treated alongside this. Reflux and post-nasal drip that irritate the larynx are managed if present, and where anxiety is a genuine contributor it is addressed in its own right. Inspiratory muscle training can help some athletes.

Where symptoms are severe and clearly supraglottic and do not respond to good conservative treatment, referral to a specialist centre for consideration of supraglottoplasty, a procedure to trim the collapsing supraglottic tissue, is an option, and rarely other targeted treatments are used in specific glottic cases.

For the SEM clinician the practical path is to recognise EILO, avoid escalating asthma treatment that will not help, and refer promptly for laryngoscopy and breathing therapy. Because the mainstay of treatment is behavioural rather than pharmacological, EILO also does not raise the anti-doping considerations that treating EIB with beta-2 agonists can.

The outlook is encouraging. Most athletes with EILO improve substantially once they learn and rehearse the right breathing techniques, and many return to full training and competition without limitation, which is a strong reason to make the diagnosis rather than leave an athlete labelled with untreatable asthma.

Practising the techniques in training helps them become automatic under the pressure of competition. Where an athlete does not improve as expected, the diagnosis and its contributors deserve another look, since coexisting asthma, unaddressed reflux or anxiety, or occasionally a cardiac or structural cause, may be part of the picture rather than treatment failure alone.

• •International nomenclature and consensus statements from respiratory and laryngology societies define inducible laryngeal obstruction and its exercise-induced form and support continuous laryngoscopy during exercise as the reference test.
• •Sport and exercise medicine and respiratory literature recognise EILO as a common cause of exertional dyspnoea in young athletes that is frequently mislabelled as asthma.
• •Speech and language therapy and respiratory physiotherapy guidance underpin the breathing retraining that is first-line treatment.
• •United Kingdom asthma guidance remains relevant for assessing and treating coexisting asthma, which can occur alongside EILO.

• •Exercise-induced laryngeal obstruction is inappropriate laryngeal narrowing at peak exercise, causing inspiratory, throat-level difficulty that clears within minutes.
• •It is distinguished from exercise-induced bronchoconstriction, which causes an expiratory wheeze building after exercise that responds to inhalers.
• •Obstruction may be glottic or supraglottic, with the supraglottic pattern common in exercise.
• •The definitive test is continuous laryngoscopy during exercise, since resting laryngoscopy is usually normal.
• •First-line treatment is breathing retraining with speech and language therapy or physiotherapy, not inhalers.
• •Severe refractory supraglottic obstruction may be referred for consideration of supraglottoplasty, and EILO can coexist with asthma.