Exercise bronchoconstriction: test before treating

A 19-year-old swimmer trains twice a day in an indoor pool. For a few months, she has been coughing and feeling chest tightness in the minutes after the hardest sets, and she thinks she is "out of shape". A teammate lends her his inhaler, and she starts using it before almost every training session. The coach asks whether that is asthma, whether the athlete can compete and whether the medication is allowed. The case is fictional, and the scene is common in pools, ice rinks, ski slopes and soccer fields.

International guidelines answer with a clear order: first confirm bronchoconstriction with a lung function test provoked by exercise or by a surrogate, and only then treat, because symptoms alone are often wrong (Parsons, 2013). Treatment has also changed: in mild asthma, the reliever strategy with inhaled corticosteroid and formoterol can also serve before exercise (GINA, 2026).

Key points

• Exercise-induced bronchoconstriction is the acute narrowing of the airway caused by exercise, in people with or without known asthma (Parsons, 2013).
• Diagnosis depends on the fall in lung function after exercise or a surrogate test, not on symptoms (Parsons, 2013).
• In a group of 97 professional soccer players, 27 had a positive test, and symptoms did not predict the result (Jackson, 2018).
• Exercise-induced laryngeal obstruction mimics bronchoconstriction and calls for another type of test (Ersson, 2020).
• The short-acting bronchodilator before exercise remains a strong ATS recommendation, but daily use leads to tolerance (Parsons, 2013).
• Frequent symptoms with exercise usually indicate poorly controlled asthma, and GINA advises reviewing technique, adherence and treatment with inhaled corticosteroid (GINA, 2026).

Summary

• What exercise-induced bronchoconstriction is
• How often it happens and in whom
• Why the airway closes: water, heat and mediators
• Symptoms mislead: diagnosis depends on the test
• The differential: larynx, conditioning and other causes
• Treatment: medication before exercise and asthma control
• Measures without medication and the elite athlete
• How NEXO helps train this reasoning
• Frequently asked questions
• Take-home messages

What exercise-induced bronchoconstriction is

The American Thoracic Society guideline defines exercise-induced bronchoconstriction as the acute narrowing of the airway that occurs in response to exercise (Parsons, 2013). The panel preferred this name over "exercise-induced asthma", because the old term suggests that exercise causes asthma or that everyone with the condition has chronic asthma. Bronchoconstriction appears in most people with asthma, but also in athletes without a prior diagnosis.

Bonini and Palange reinforce the distinction. In the person with uncontrolled asthma, exercise is just another trigger for an already inflamed airway. In the athlete without asthma, especially in endurance sports, repeated hyperventilation with cold, dry or polluted air seems to damage the epithelium and create a form of the condition of its own (Bonini, 2015). The difference matters for treatment and follow-up.

When symptoms appear

The review by Aggarwal and colleagues summarizes the typical timing: bronchoconstriction arises 2 to 5 minutes after the end of exercise, peaks around 10 minutes and resolves in about 60 minutes (Aggarwal, 2018). The ATS guideline describes a duration of 30 to 90 minutes in the absence of treatment (Parsons, 2013). Symptoms include cough, chest tightness, wheezing, shortness of breath, excess mucus and the feeling of being "out of shape" in someone who is well trained.

GINA notes that, in asthma, symptoms and bronchoconstriction usually worsen after exercise ends. Shortness of breath or wheezing during exercise may have other explanations, such as obesity, lack of conditioning or induced laryngeal obstruction (GINA, 2026). This difference in timing is a useful clinical clue.

Severity	Fall in FEV1 relative to the value before exercise	Source
Diagnostic criterion	10 in every 100 parts or more	Parsons, 2013
Mild	From 10 to less than 25 in every 100 parts	Parsons, 2013
Moderate	From 25 to less than 50 in every 100 parts	Parsons, 2013
Severe	50 in every 100 parts or more	Parsons, 2013

FEV1 is the forced expiratory volume in the first second, measured by spirometry. The drop is calculated from the lowest value recorded in the 30 minutes after exercise.

How often it happens and in whom

The frequency depends heavily on the population and the method. The review by Aggarwal estimates that bronchoconstriction occurs in about 5 to 20 out of every 100 people in the general population and in about 90 out of every 100 people with asthma (Aggarwal, 2018). The ATS guideline cites studies in Olympic and elite athletes with prevalence between 30 and 70 out of every 100, depending on the sport and the test used (Parsons, 2013).

A systematic review with 60 studies and 7501 adult athletes estimated bronchoconstriction in 23 out of every 100 athletes, with atopy more frequent in athletes with the condition and in men (Rodriguez Bauza, 2020). In adolescents at a Swedish sports school, the estimated prevalence was similar, about 23 out of every 100 (Ersson, 2020).

The environment of each sport

The ATS guideline links part of this frequency to the environment. In ice rink athletes, the prevalence of close to 30 out of every 100 was associated with cold, dry air combined with pollutants from fuel-powered ice resurfacing machines. In cross-country skiers, airway injury was attributed to high ventilation with cold, dry air. In competitive swimmers, asthma and bronchoconstriction, from 11 to 29 out of every 100, were associated with trichloramines in the air of indoor pools (Parsons, 2013).

The topic connects with the post about thunderstorm asthma, in which the trigger is pollen fragmented by rain. Here the trigger is the ventilation of exertion itself, and the training environment modulates the risk. GINA recommends discussing exposure to pollutants, allergens and chlorine with the athlete, especially during periods of intense training (GINA, 2026).

Why the airway closes: water, heat and mediators

During intense exercise, a person breathes large volumes of air through the mouth, and this air must be warmed and humidified in a short time. The osmotic theory, developed by Sandra Anderson's group, proposes that water loss from the airway surface increases the osmolarity of the fluid lining the epithelium, and this triggers the release of mediators (Bonini, 2015). The drier and colder the air and the higher the ventilation, the greater the chance of a positive response, which helps explain the high frequency in winter sports.

The ATS guideline points to the two most important factors: sustained high ventilation during exercise and the water content of the inspired air (Parsons, 2013). The thermal theory adds that vasodilation during rewarming of the airway after exertion may also contribute (Bonini, 2015).

What the sputum showed

Hallstrand and colleagues studied induced sputum from 25 people with asthma and bronchoconstriction, before and 30 minutes after an exercise test. After exertion, histamine, tryptase and cysteinyl leukotrienes increased in the airway, and there was release of columnar epithelial cells, whose quantity was associated with the severity of the condition (Hallstrand, 2005). Montelukast and loratadine reduced the release of mediators, but not that of epithelial cells. The authors concluded that there is an inflammatory basis for exercise-induced bronchoconstriction.

This mechanism explains two practical observations. The first is the refractory period: after an episode, some people become less responsive to a new stimulus for up to 4 hours (Parsons, 2013). The second is that drugs that block mediators, such as the leukotriene antagonist, have a role in treatment.

Symptoms mislead: the diagnosis depends on the test

The ATS guideline is direct: the diagnosis is made by the change in lung function brought on by exercise, not by symptoms. The presence or absence of specific respiratory symptoms has very low predictive value for confirmed bronchoconstriction (Parsons, 2013). The study with professional soccer players showed the problem in practice: among 97 athletes assessed in the preseason, 27 had a positive test, 10 of them with no prior diagnosis, and symptoms did not predict the result (Jackson, 2018).

The reasoning is that of pretest probability. An indoor pool swimmer with a cough after sets has a reasonable but still uncertain probability, and the test changes the decision. Treating without testing can label an athlete with asthma she does not have, or miss another cause. Aggarwal and colleagues note that underdiagnosis and misdiagnosis are common (Aggarwal, 2018).

The available tests

The standardized exercise test measures FEV1 before and several times in the 30 minutes after exertion. The Italian consensus for children describes at least 6 minutes of maximal exercise on a treadmill, or free running in younger children, with spirometry at 5, 10, 15 and 30 minutes (Fainardi, 2024). The ATS notes that the sport-specific exercise, tested in the sport's own environment, is probably the most relevant for the elite athlete (Parsons, 2013).

Because the field test is hard to standardize, there are substitutes: voluntary eucapnic hyperpnea, in which the person breathes dry air at high ventilation for a few minutes, inhalation of hypertonic saline and mannitol powder (Parsons, 2013). The review by Hull and colleagues considers eucapnic hyperpnea central to the athlete's algorithm, with a positive result when FEV1 falls by 10 in every 100 parts or more within 20 minutes, but notes that sensitivity and repeatability vary and that it does not deserve the gold standard label (Hull, 2016).

Test	How it works	Note
Laboratory exercise	Treadmill or bicycle with dry air, serial spirometry up to 30 minutes	Standardized, may not reproduce the sport
Field test	The sport itself, in its own environment	More specific, hard to control and less sensitive
Voluntary eucapnic hyperpnea	High ventilation with dry air and added CO2	Widely used in athletes; variable sensitivity and repeatability
Inhaled mannitol or hypertonic saline	Direct osmotic stimulus in the airway	Laboratory alternative

Source: Parsons, 2013 and Hull, 2016.

Preparing for the test

Hull and colleagues note that the athlete must be clinically well, with no respiratory infection in the previous 6 weeks, must avoid caffeine and exercise on the day of the test, so as not to induce the refractory period, and must stop inhaled medication for the time set out in the guidelines (Hull, 2016). A negative test done under a bronchodilator or after warm-up may be a false negative.

The differential: larynx, conditioning and other causes

The main differential is exercise-induced laryngeal obstruction, in which the larynx closes during exertion. In a study with adolescents from a sports school, laryngeal obstruction was estimated at about 8 in every 100 participants, and shortness of breath reported by the athlete was a weak indicator of both bronchoconstriction and laryngeal obstruction (Ersson, 2020). The authors conclude that standardized tests should be offered.

The Italian consensus for children sums up the clues: laryngeal obstruction usually causes inspiratory stridor during activity, does not respond to salbutamol and is more common in female athletes (Fainardi, 2024). Bronchoconstriction, in turn, worsens after exercise and improves with a bronchodilator. The diagnosis of laryngeal obstruction is made with continuous laryngoscopy during exercise.

Comparing the two hypotheses side by side avoids months of an inhaler with no effect. GINA also lists obesity and lack of conditioning among the causes of shortness of breath on exercise that can be confused with asthma (GINA, 2026). Arrhythmias, heart disease and exercise-induced anaphylaxis enter the reasoning when there is fainting, palpitations, hives or a drop in blood pressure, as in the post on differential diagnosis of anaphylaxis.

Clue	Exercise-induced bronchoconstriction	Exercise-induced laryngeal obstruction
Timing	Peak minutes after the end of exertion	During activity
Sound	Expiratory wheeze, cough	Inspiratory stridor
Response to salbutamol	Improvement	Absent
Test	Serial spirometry after exercise or a substitute	Continuous laryngoscopy during exercise

Source: Fainardi, 2024 and Ersson, 2020.

Treatment: medication before exercise and asthma control

The ATS guideline makes a strong recommendation, with high-quality evidence, for a short-acting inhaled bronchodilator before exercise in all people with exercise-induced bronchoconstriction, generally 15 minutes before (Parsons, 2013). The protective effect lasts 2 to 4 hours. The Italian consensus for children repeats the same first choice, 15 to 20 minutes before activity (Fainardi, 2024).

The limit is frequency. The ATS notes that daily use of beta-agonists, alone or with inhaled corticosteroid, leads to tolerance: protection lasts less time and recovery after exercise is slower (Parsons, 2013). GINA adds that taking a short-acting bronchodilator regularly for just one week already increases exercise-induced bronchoconstriction, airway hyperresponsiveness and airway inflammation (GINA, 2026).

When the bronchodilator before training is not enough

For those who still have symptoms despite the bronchodilator before exercise, or need it every day, the ATS recommends adding a controller: daily inhaled corticosteroid, daily leukotriene antagonist or mast cell stabilizer before exercise, all with a strong recommendation (Parsons, 2013). The maximum effect of the inhaled corticosteroid can take up to 4 weeks. The leukotriene antagonist has a smaller effect, but it lasts up to 24 hours and does not cause tolerance.

The guideline advises against a long-acting bronchodilator alone and daily, and advises against antihistamine in people without allergy; in those with allergy and persistent symptoms, the antihistamine is a weak suggestion (Parsons, 2013). GINA notes that aerosol mast cell stabilizers have been discontinued worldwide (GINA, 2026).

What GINA 2026 adds

GINA addresses bronchoconstriction within the asthma plan. Regular inhaled corticosteroid substantially reduces exercise-induced bronchoconstriction, and adequate training and warm-up reduce the incidence and severity of episodes (GINA, 2026). In a 6-week study in mild asthma, low-dose budesonide and formoterol, used for relief and before exercise, reduced bronchoconstriction similarly to daily corticosteroid with a short-acting bronchodilator. GINA concludes that those already using corticosteroid with formoterol for relief can use the same inhaler before exercise, if needed, without a separate prescription for a short-acting bronchodilator.

The most useful point for clinical practice may be this: symptoms that escape with exercise usually indicate poorly controlled asthma. GINA advises checking inhaler technique and adherence and, after that, adjusting treatment with inhaled corticosteroid, which generally reduces symptoms linked to exercise (GINA, 2026). The choice among the options is a shared decision, which takes into account the sport, training times and the athlete's preference.

Situation	What the guidelines indicate	Source
Confirmed bronchoconstriction	Short-acting bronchodilator about 15 minutes before exercise, less than daily	Parsons, 2013
Mild asthma controlled with corticosteroid and formoterol	Same inhaler before exercise, if necessary	GINA, 2026
Symptoms despite pre-treatment or daily use	Daily inhaled corticosteroid or leukotriene antagonist	Parsons, 2013
Symptoms that escape with exercise in asthma	Review technique and adherence, then adjust the inhaled corticosteroid	GINA, 2026
All people with the condition	Interval or combined warm-up before exercise	Parsons, 2013

Non-drug measures and the elite athlete

The ATS makes a strong recommendation for interval or combined warm-up before planned exercise for all people with the condition (Parsons, 2013). A typical warm-up consists of 10 to 15 minutes of moderately vigorous exercise and reduces bronchoconstriction in the following 2 hours, the so-called refractory period. The phenomenon, however, varies between people and may not occur in athletes without asthma.

For people who exercise in the cold, the ATS suggests, with low-quality evidence, a device that warms and humidifies the air, such as a mask; the guideline also mentions breathing through a mask or a scarf (Parsons, 2013). The Italian consensus adds warm-up and cool-down, avoiding exercise in intense cold or in a very polluted environment, avoiding cigarette smoke, keeping regular physical activity, avoiding allergens and correcting excess weight (Fainardi, 2024).

The elite athlete

GINA notes that high-level athletes have more asthma, bronchoconstriction, rhinitis, chronic cough, exercise-induced laryngeal obstruction and recurrent respiratory infections than non-athletes. Airway hyperresponsiveness is common even without symptoms, and athlete's asthma often shows less relationship between symptoms and lung function and less eosinophilic inflammation (GINA, 2026). The document recommends adequate anti-inflammatory treatment, especially with inhaled corticosteroid, and minimal use of beta-agonists, to avoid tolerance.

In the study with soccer players, 7 of the 27 athletes with a positive test returned for reassessment after 9 weeks of treatment and showed improvement in spirometry after the provocation test (Jackson, 2018). Low adherence to follow-up led the authors to advocate educating athletes about the condition from the start.

Anti-doping

Use of short-acting bronchodilator is more common in elite athletes than in the general population, especially in endurance sports (Vertadier, 2022). The 2026 Prohibited List of the World Anti-Doping Agency prohibits all beta-2 agonists, in and out of competition, and makes exceptions only for four of them by inhalation and within daily limits: salbutamol up to 1600 micrograms in 24 hours, with at most 600 micrograms in 8 hours; formoterol up to 54 micrograms in 24 hours; salmeterol up to 200 micrograms in 24 hours; and vilanterol up to 25 micrograms in 24 hours (WADA, 2026). Outside these exceptions, such as inhaled terbutaline or any beta-2 agonist by mouth, the athlete needs a therapeutic use exemption. Glucocorticoids are prohibited only in competition when used by injectable, oral or rectal route; the inhaled route is permitted within the approved indications (WADA, 2026). Salbutamol in urine above 1000 ng/mL is treated as an adverse analytical finding, unless a controlled pharmacokinetic study shows that it came from inhaled use within the limit. GINA advises consulting the World Anti-Doping Agency website and documenting the effects of any therapeutic test (GINA, 2026). The list changes every year, and objective confirmation of the diagnosis helps justify the treatment.

Children and sport

The Italian consensus states that children with bronchoconstriction can practice physical activity and competitive sport when symptoms and asthma are controlled with adequate treatment (Fainardi, 2024). Sports in which inhaling salbutamol is difficult, such as diving, are usually discouraged. Regular reassessments help review the treatment and maintain the recommended level of physical activity. Time is also a test: the response to treatment over the weeks helps confirm or revise the diagnosis.

How NEXO helps train this reasoning

In NEXO, the case of the day is fictional, with a real clinical presentation and up to six progressive clues, and you propose the diagnosis by searching for the ICD-10 code. Separating exercise-induced bronchoconstriction from laryngeal obstruction, from poorly controlled asthma or from a cardiac cause is the kind of reasoning that is trained clue by clue. The post about syncope in the emergency department helps separate benign from serious fainting, and the post about heuristics shows when the shortcut "cough during training is asthma" helps and when it gets in the way.

The limits on using the game are described on the Economy page of NEXO. If you research the teaching of clinical reasoning, the page for Researcher explains how to get in touch. Professionals who write or review cases find information on Curator and on Creators, and institutions can learn about the proposal on the partnerships page.

Frequently asked questions

Is exercise-induced bronchoconstriction the same as asthma?

Bronchoconstriction happens in most people with asthma, but also in people without asthma, especially endurance athletes. That is why the ATS prefers this name to "exercise-induced asthma" (Parsons, 2013).

Can it be diagnosed from symptoms alone?

Symptoms have low predictive value. The diagnosis depends on a fall in FEV1 of at least 10 in every 100 parts after exercise or a surrogate test (Parsons, 2013).

Is using the inhaler every day before training a problem?

Daily use of a beta-agonist causes tolerance and reduces protection. Anyone who needs the medicine every day should review treatment with a doctor, usually with a controller (Parsons, 2013).

Does warm-up really help?

The ATS recommends interval or combined warm-up for everyone, because it can induce a refractory period of about 2 hours, although the effect varies between people (Parsons, 2013).

What if the inhaler has no effect at all?

Lack of response to salbutamol, especially with inspiratory noise during exertion, suggests exercise-induced laryngeal obstruction, which calls for laryngoscopy during exercise (Fainardi, 2024).

Take-home messages

• Exercise-induced bronchoconstriction occurs in people with and without asthma, and it is common in athletes.
• The diagnosis requires a fall in FEV1 of at least 10 in every 100 parts after exercise or a surrogate.
• Symptoms alone are often wrong, and laryngeal obstruction is the major differential.
• A short-acting bronchodilator before exercise, less than daily, is the ATS first option.
• In mild asthma relieved with corticosteroid and formoterol, the same inhaler can be used before exercise.
• Frequent symptoms with exercise call for a review of asthma control.
• Warm-up, warmed air in the cold and attention to the training environment complete the care.

Play the case of the day on NEXO.

References

1. Parsons JP, Hallstrand TS, Mastronarde JG, et al. An official American Thoracic Society clinical practice guideline: exercise-induced bronchoconstriction. Am J Respir Crit Care Med. 2013;187(9):1016-1027. PMID 23634861. DOI 10.1164/rccm.201303-0437ST.
2. Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention, 2026. Updated May 2026. ginasthma.org.
3. Aggarwal B, Mulgirigama A, Berend N. Exercise-induced bronchoconstriction: prevalence, pathophysiology, patient impact, diagnosis and management. NPJ Prim Care Respir Med. 2018;28(1):31. PMID 30108224. DOI 10.1038/s41533-018-0098-2.
4. Hull JH, Ansley L, Price OJ, et al. Eucapnic Voluntary Hyperpnea: Gold Standard for Diagnosing Exercise-Induced Bronchoconstriction in Athletes? Sports Med. 2016;46(8):1083-1093. PMID 27007599. DOI 10.1007/s40279-016-0491-3.
5. Bonini M, Palange P. Exercise-induced bronchoconstriction: new evidence in pathogenesis, diagnosis and treatment. Asthma Res Pract. 2015;1:2. PMID 27965757. DOI 10.1186/s40733-015-0004-4.
6. Hallstrand TS, Moody MW, Wurfel MM, et al. Inflammatory basis of exercise-induced bronchoconstriction. Am J Respir Crit Care Med. 2005;172(6):679-686. PMID 15947280. DOI 10.1164/rccm.200412-1667OC.
7. Jackson AR, Hull JH, Hopker JG, et al. Impact of detecting and treating exercise-induced bronchoconstriction in elite footballers. ERJ Open Res. 2018;4(2):00122-2017. PMID 29692994. DOI 10.1183/23120541.00122-2017.
8. Ersson K, Mallmin E, Malinovschi A, et al. Prevalence of exercise-induced bronchoconstriction and laryngeal obstruction in adolescent athletes. Pediatr Pulmonol. 2020;55(12):3509-3516. PMID 33002318. DOI 10.1002/ppul.25104.
9. Vertadier N, Trzepizur W, Faure S. Overuse of Short-Acting Beta-2 Agonists (SABAs) in Elite Athletes: Hypotheses to Explain It. Sports (Basel). 2022;10(3):36. PMID 35324645. DOI 10.3390/sports10030036.
10. Fainardi V, Grandinetti R, Mussi N, et al. Exercise-induced bronchoconstriction in children: Delphi study and consensus document about definition and epidemiology, diagnostic work-up, treatment, and follow-up. Respir Res. 2024;25(1):445. PMID 39731113. DOI 10.1186/s12931-024-03078-5.
11. Rodriguez Bauza DE, Silveyra P. Sex Differences in Exercise-Induced Bronchoconstriction in Athletes: A Systematic Review and Meta-Analysis. Int J Environ Res Public Health. 2020;17(19):7270. PMID 33027929. DOI 10.3390/ijerph17197270.
12. World Anti-Doping Agency. The 2026 Prohibited List: International Standard. Montreal: WADA; 2025. In force since January 1, 2026. Official PDF.