The investigators propose a study that compares breathlessness and airway obstruction during intense exercise in 34 children and adolescents with Exercise-Induced Laryngeal Obstruction after breathing in ipratropium bromide or placebo. It is hypothesized that breathlessness and airway obstruction will be lower following breathing in ipratropium bromide compared with placebo.

Many children and adolescents struggle with breathing problems during exercise. These symptoms can lead them to underperform, quit sports, and in some cases, stop being active altogether. One under-recognized cause is Exercise-Induced Laryngeal Obstruction (EILO), a narrowing of the airway at the level of the voice box. Approximately 5-8% of adolescents and 20-40% of adolescent athletes have EILO, an estimated 4-6 million nationwide. The most common treatment for EILO is Speech Therapy, with or without Physical Therapy. Where available, this requires significant time and financial commitment from patients and their families to attend therapy sessions and complete at-home exercises.

Case reports as early as 1985 have suggested aerosolized ipratropium bromide as an effective EILO treatment. One larger study could not confirm this observation. However, this study used an outcome measure with low reliability and validity, did not use a placebo control, and administered a low dose of ipratropium bromide too close to exercise.

The investigators propose a study that compares breathlessness and airway obstruction during intense exercise in 34 children and adolescents with EILO following inhalation of a higher dose of nebulized ipratropium bromide with placebo. It is hypothesized that breathlessness and airway obstruction will be lower following inhalation of ipratropium bromide compared with placebo.

Inclusion Criteria:

• Patients must be diagnosed with EILO confirmed by Continuous Laryngoscopy During Exercise
• Patients must be able to complete exercise testing
• Patients must report dyspnea
• Patients must have given assent with parental consent, understand all study procedures, and comply with them for the entire length of the study.

Exclusion Criteria:

• Patients that do not have EILO.
• Patients who did not undergo diagnostic CPET with CLE.
• Patients with hypersensitivity to atropine or its derivatives due to structural similarity with ipratropium bromide.
• Patients with a history of atrial flutter and/or fibrillation
• Patients taking anticholinergic medications that cannot be paused for 24 hours.
• Unable to perform exercise tests
• Current drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements.
• Inability or unwillingness of patient or parent/legally authorized representative to give written informed consent.

The investigators anticipate the institution's IRB/legal team will not approve sharing IPD.