Exercise-Induced Bronchoconstriction Testing

Meghan F. Raleigh

Fred H. Brennan Jr

EPIDEMIOLOGY

Exercise-induced bronchoconstriction (EIB) is a common medical condition that affects at least 10%-15% of athletes (9).
Exercise-induced asthma (EIA) is the presence of similar symptoms in a patient with a known diagnosis of asthma (18). The prevalence of EIB in asthmatic patients is 80%-90% (19).
Respiratory symptoms alone are insensitive in predicting bronchospasm in athletes (11).
Common respiratory symptoms suggestive of asthma (coughing, wheezing, etc.) have only a 60%-70% positive predictive value for EIB (15,16).

INDICATIONS FOR EIB TESTING

An athlete with signs or symptoms suggestive of EIA.
An athlete with known chronic asthma may be tested for an exercise-triggering event.
An athlete with exertional dyspnea, once cardiac etiologies have been clinically and/or diagnostically eliminated.

CONTRAINDICATIONS FOR EIB TESTING

Active or recent pulmonary infection within past 30 days.
Ongoing or recent exacerbation of asthma.
Known allergy to methacholine (methacholine challenge).
An athlete using inhaled corticosteroids may still be tested; however, the provocation test may be falsely negative in up to 50% of patients (2,17).

EIB PROVOCATIVE TESTING

Exercise Challenge

A baseline pulmonary function test (PFT) should be performed and results recorded prior to this provocative test.
The sensitivity and specificity of this test for identifying EIB in athletes are approximately 65% (6,9).
The challenge should be sport-specific and conducted in the environment in which athletes most commonly experience their symptoms (7).
An exercise challenge may be used as a first-line diagnostic study.

Conducting an Exercise Challenge

Allow athletes to stretch, but do not allow them to exercise or warm up prior to the challenge. A warm-up period may result in a false-negative result.
Obtain a baseline PFT or peak expiratory flow rate (PEFR). Record FEV₁ (forced expiratory volume in 1 second) and FEF\_25-75 (force expiratory flow during the middle portion of expiration), or PEFR.
The sport-specific exercise should be conducted for 8-10 minutes at 85%-90% of maximum calculated heart rate (220 − age in years = calculated maximum heart rate).
After 10 minutes of exercise, allow a 1-minute rest. Check PFT or PEFR three times and record the best result.
Repeat these measurements at 3, 5, 10, 15, and 20 minutes after termination of the exercise challenge.
A decrease of > 10% in the FEV₁ or PEFR and/or a decrease in FEF_25-75 of > 20% are diagnostic for EIB (10,13,14).