What is the treatment for exercise-induced asthma?

Treatment of Exercise-Induced Bronchoconstriction

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

First-Line Pharmacologic Treatment

Inhaled SABAs (such as albuterol) are the gold standard for preventing exercise-induced bronchoconstriction, providing protection in 80-95% of patients when taken 5-20 minutes before exercise. 1, 2, 3

• SABAs work by stimulating β2-receptors on airway smooth muscle, causing bronchodilation and preventing mast cell degranulation. 1
• The protective effect lasts 2-4 hours after administration. 1
• SABA use should be less than daily on average—ideally less than 4 times per week—to prevent tolerance development. 2
• Patients who fail to respond to pre-exercise SABA (15-20% of cases) require additional controller therapy. 1

Critical Warning About SABA Tolerance

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

Second-Line Options for Persistent Symptoms

When patients require SABA more than 4 times per week or experience breakthrough symptoms despite pre-exercise SABA, add daily controller therapy:

Daily Inhaled Corticosteroids (ICS)

• ICS therapy decreases the frequency and severity of exercise-induced bronchoconstriction and should be the preferred controller medication for patients with persistent symptoms. 1, 2
• ICS reduces underlying airway inflammation that contributes to exercise-induced bronchoconstriction. 1
• However, ICS does not eliminate exercise-induced bronchoconstriction in all patients and may not prevent tolerance from daily LABA therapy. 1

Daily Leukotriene Receptor Antagonists (LTRAs)

• Montelukast 10 mg taken daily provides 50-60% protection for up to 24 hours and represents an alternative controller option. 2, 4
• When taken as a single dose 2 hours before exercise, montelukast demonstrates statistically significant protective benefit, with mean maximum percent fall in FEV1 of 13% versus 22% for placebo at 2 hours post-dose. 5
• LTRAs do not cause tolerance with regular use, making them advantageous for patients requiring daily therapy. 1, 4
• LTRAs cannot reverse existing airway obstruction and provide incomplete protection compared to SABAs. 1
• If already taking montelukast daily for chronic asthma or allergic rhinitis, do not take an additional dose for exercise-induced bronchoconstriction. 5

Mast Cell Stabilizing Agents

• Cromolyn sodium and nedocromil provide 50-60% protection for 1-2 hours when administered shortly before exercise. 1, 4
• These agents do not induce tolerance and can be used multiple times daily without significant adverse effects. 4
• These agents are no longer available in the United States but remain available internationally. 1

Long-Acting β2-Agonists (LABAs): Important Cautions

Never use LABAs as monotherapy for exercise-induced bronchoconstriction. 2, 3

• LABAs can provide protection for up to 12 hours when used intermittently. 1, 4
• Daily LABA use leads to tolerance, reducing both duration and magnitude of protection against exercise-induced bronchoconstriction. 1
• LABAs should only be used in combination with ICS for patients with underlying chronic asthma. 1

Non-Pharmacologic Interventions

Incorporate these evidence-based strategies to reduce the severity of exercise-induced bronchoconstriction:

Pre-Exercise Warm-Up

• Perform a 10-15 minute warm-up period before vigorous exercise to induce a refractory period lasting up to 3 hours, during which repeat exercise causes less bronchospasm. 2, 3, 6
• Interval or combination warm-up exercises are most effective. 3

Environmental Modifications

• Wear a face mask or scarf over the mouth during cold weather exercise to warm and humidify inspired air, reducing airway cooling and drying. 2, 3
• Exercise in warm, humidified environments when possible, as cold, dry air increases the severity of exercise-induced bronchoconstriction. 1, 6
• Avoid high-pollution environments and known allergens. 3

Physical Conditioning

• Improved aerobic fitness and good control of baseline bronchial reactivity help diminish the effects of exercise-induced bronchoconstriction. 6
• Choose sports with lower minute ventilation when possible to reduce risk. 3

Treatment Algorithm

1. All patients: SABA 15 minutes before exercise (use <4 times per week) 1, 2
2. If SABA needed ≥4 times per week: Add daily ICS as preferred controller 2
3. Alternative to ICS: Daily LTRA (montelukast 10 mg) 2, 5
4. If on daily controller and still symptomatic: Continue daily controller + pre-exercise SABA 1
5. Never: Use LABA as monotherapy 2, 3

Common Pitfalls to Avoid

• Do not use SABAs daily for prevention—this leads to tolerance and reduced efficacy. 1
• Do not take an additional dose of montelukast for exercise if already taking it daily for chronic asthma or allergic rhinitis. 5
• Do not use LABAs without ICS due to serious safety concerns. 2
• Do not rely on SABAs for acute relief during exercise—they must be taken prophylactically 15 minutes before exercise. 1
• Always have rescue SABA available even when using controller medications. 3, 5