What is the recommended management for exercise‑induced asthma?

Management of Exercise-Induced Asthma

For all patients with exercise-induced bronchoconstriction, administer an inhaled short-acting β2-agonist (SABA) such as albuterol 15 minutes before exercise as first-line therapy. 1, 2

First-Line Treatment: Pre-Exercise SABA

• Inhaled SABAs given 15 minutes before exercise provide 80-95% protection for 2-4 hours and represent the most effective single-dose agents for preventing exercise-induced bronchoconstriction. 1, 2, 3
• The magnitude of benefit is substantial—patients experience a 26% reduction in maximum FEV1 fall compared to placebo, based on pooled randomized trials. 1
• SABA use must remain intermittent (less than daily on average, ideally less than 4 times per week) to prevent tolerance development. 4, 2
• Daily or frequent SABA use signals inadequate asthma control and necessitates stepping up to daily controller medication. 4

Critical Pitfall with SABAs

• Regular daily use of β2-agonists causes tolerance manifested as reduced duration of protection, reduced magnitude of protection, and prolonged recovery time after exercise. 1, 2
• This tolerance occurs due to desensitization of β2-receptors on mast cells and airway smooth muscle. 1

When to Add Daily Controller Therapy

If SABAs are needed more than 2 days per week for symptom relief, add daily controller medication. 4

Preferred Second-Line Option: Daily Leukotriene Receptor Antagonist

• Daily montelukast is the preferred second-line option for patients not responding to SABA alone. 4
• Montelukast provides 50-60% protection for up to 24 hours and does not cause tolerance with regular use, making it superior to daily β2-agonist therapy. 4, 3
• This agent can be used daily or intermittently without loss of efficacy. 4

Alternative Second-Line Option: Daily Inhaled Corticosteroids

• Inhaled corticosteroids decrease the frequency and severity of exercise-induced bronchoconstriction more effectively than leukotriene modifiers. 4
• Maximum benefit requires up to 4 weeks of treatment and is dose-dependent. 4
• ICS typically reduce the extent of exercise-induced bronchoconstriction by 50% or more. 5

What NOT to Use as Monotherapy

• Never use long-acting β2-agonists (LABAs) as monotherapy due to increased risk of asthma-related mortality. 4, 2
• Daily LABA use causes tolerance with reduced duration and magnitude of protection. 4, 2
• If symptoms persist despite daily ICS, add a LABA to ICS as combination therapy—never as monotherapy. 4

Non-Pharmacologic Strategies (Adjunctive)

• Perform a 10-15 minute warm-up before exercise to induce a refractory period that reduces bronchoconstriction severity by up to 50%. 4, 2
• Use face masks or scarves during cold weather exercise to warm and humidify inspired air, reducing osmotic triggers. 4, 2
• Optimize general physical conditioning and maintain healthy weight if obese. 1

Treatment Algorithm Summary

1. Start all patients on pre-exercise SABA (15 minutes before activity), used intermittently 1, 2
2. If SABA needed >2 days/week → Add daily montelukast 4
3. If symptoms persist or are severe → Switch to or add daily ICS 4
4. If still inadequate after 4 weeks of ICS → Add LABA to ICS (never alone) 4
5. Always incorporate warm-up exercises and environmental modifications 4, 2

Monitoring Requirements

• Track rescue SABA frequency—if still needed more than twice weekly after 4 weeks of daily controller therapy, reassess the treatment plan. 4
• Regular follow-up is essential due to significant intra-patient and inter-patient variability in medication effectiveness. 4
• After starting daily controller therapy, monitor for adequate symptom control and ability to exercise without significant respiratory limitation. 4