Background Respiratory problems are common complaints among athletes, potentially influencing their sport performances as well as their health. Exertional dyspnoea unresponsive to asthma medication have been referred to as ‘mysterious breathing problems’.

Objective To address if exercise related breathing problems in athletes with exercise induced laryngeal obstruction (EILO) are perceived as uncontrolled asthma.

Design Retrospective descriptive cross sectional study.

Setting Register data from hospital-based national reference clinic during 2013–2016. Symptoms, previous diagnostic work-up and pulmonary function were obtained from referral letters or chart reviews. EILO was diagnosed from video-recorded laryngoscopy performed during maximal cardiopulmonary treadmill exercise (CLE-test).

Participants Elite athletes competing on national and/or international level, referred for work-up due to exercise induced breathing problems.

Assessment of risk factors Respiratory symptoms, lung function tests, asthma, use of asthma medication, EILO.

Main outcome measurements Respiratory symptoms, lung function test results, asthma, use of asthma medication, EILO with laryngeal movements scored from video-recorded CLE tests using a standardized system, blinded to the clinical data.

Results EILO was diagnosed in 94/101 athletes, of whom 70/94 had moderate/severe supraglottic obstructions and only 3 had a primary vocal cord dysfunction (VCD). Test for asthma was available in 76/101 athletes; 28 confirming and 38 excluding asthma. In total 83/101 athletes had used asthma medications, 39 reporting current use. Only 4 reported that asthma medication had been effective, 3 of whom with a positive test for asthma. However, all these 4 subjects were also diagnosed with EILO; i.e. they had both conditions. Treatment for EILO resolved breathing problems in the majority.

Conclusions EILO is common in athletes, but too often referred to as ’mysterious breathing problems’. Asthma does not rule out EILO as comorbidities are common. Apparent persistence of respiratory symptoms must not lead to indiscriminate escalation of asthma treatment, as symptoms may be due to undiagnosed and treatable laryngeal obstruction.