Serghei Covantev; Alexandru Corlateanu; Victor Botnaru

Review Article

Austin J Pulm Respir Med 2016; 3(1): 1037.

Exercise-Induced Bronchoconstriction in Athletes

Serghei Covantev, Alexandru Corlateanu* and Victor Botnaru

Department of Respiratory Medicine, State University of Medicine and Pharmacy “Nicolae Testemitanu”, Moldova

*Corresponding author: Alexandru Corlateanu, Department of Respiratory Medicine, State University of Medicine and Pharmacy “Nicolae Testemitanu”, Stefan Cel Mare Street 165, 2004, Chisinau, Moldova

Received: November 30, 2015; Accepted: March 01, 2016; Published: March 04, 2016

Abstract

Exercise-induced bronchoconstriction is a disease with high prevalence among elite athletes and it can be up to 70%. Diagnosing this condition is essential to accurately manage the condition preserving excellent lung function among athletes. In this article is presented a review of studies on exerciseinduced bronchoconstriction, methods of diagnosis and management.

Keywords: Exercise-induced bronchoconstriction; Elite athletes

Introduction

Exercise-Induced Bronchoconstriction (EIB) describes acute airway narrowing that occurs as a result of exercise. It can occur in patients with asthma as well in patients who were previously not diagnosed with the disease [1]. Many studies have been performed in elite-level athletes that have documented prevalence of EIB varying between 30 and 70%, depending on the population, sport type, studied and methods implemented but no relationship were currently found regarding height, weight, age and gender [2-5]. The clinical symptoms of EIB include coughing, wheezing, chest pain and dyspnoea following an exercise but can often can be absent or not noticed by the athlete. Further examination often reveals some degree of atopy [6]. But it should be noted that self-reported symptoms are not always present and asymptomatic forms are very common [7].

Highly trained athletes tend to be frequently and for a long period of time exposed to cold air during winter training, to pollen allergens in spring and summer, different chemical substances used as disinfectants in swimming pools. These factors probably explain why elite athletes so often have EIB. This condition is most commonly found in endurance sports, such as cycling, swimming, or longdistance running. The occurrences of exercise-induced bronchospasm vary from 3% to 35% and depend on testing environment, type of exercise used, and athlete population tested. Still the highest risk for developing EIB in swimmers may be even higher, being 36%-79% [8].

Causes, Inflammatory State and Risks of EIB

The causes of EIB are not completely understood. Several theories have been developed during the years such as thermal and osmotic. Thermal hypothesis proposed that when prolonged cooling of the airways is followed by rapid rewarming it can result in vasoconstriction and a reactive hyperemia of the bronchial circulatory system [3,9]. The osmotic hypothesis proposes that as water is evaporated from the airway surface liquid; it becomes hyperosmolar and provides an osmotic stimulus for water to move from any cell nearby, causing cell volume loss and eventually an increased secretion of inflammatory mediators [3,9].

Still there are several immune mechanism implicated in EIB development. Several studies show that eosinophils, neutrophils and basophils migrate and cause airway inflammation, plus the number of neutrophils correlated with the number of training hours per week [10-12].

The majority of elite athletes show evidence of bronchial epithelial damage and other studies performed in animals and people indicate upregulation of pro-inflammatory cytokines, damage of small airways in mice, neutrophilic and lymphocytic inflammation with remodelling in bronchial biopsies [11,13].

Expose of smooth muscle to inflammatory substances over time can lead to changes in the contractile properties of the smooth muscle, making it more sensitive to mediators of bronchoconstriction [14].

Six hundred and fifty-nine Italian Olympic athletes were studied through four cross-sectional surveys performed during 12 years. The prevalence of asthma and/or EIB was 14.7%, with a significant increase from 2000 (11.3%) to 2008 (17.2%). The prevalence of rhinitis was 26.2%, conjunctivitis - 20%, skin allergic diseases - 14.8% and anaphylaxis - 1.1%. In 2000 sensitization to inhalant allergens was 32.7% and in 2008 it increased to 56.5%. Food, drug and venom allergy was present in 7.1%, 5.0% and 2.1% of athletes, respectively. Asthma and allergy was associated with recurrent upper respiratory tract infection in 10.3%, herpes infection in 18.2%, an abnormal T cell subset profile and a general down-regulation of serum cytokines level [15].

A study that involved 1680 Norwegian athletes and a 1680 random sample from the general population showed that the prevalence of asthma among athletes was 10% compared with 6.9% in the general population and remained so after controlling for confounders. The risk of asthma was highest in sports requiring strength and endurance. Asthma was more common among female than male athletes. Training more than 20 hours per week was associated with asthma when compared with levels of training less than 10 hours per week [16].

It is important to mention that EIB is probably a reversible condition. Forty-two elite competitive swimmers, most of them from the Finnish national team were followed for 5 years in a prospective manner. In swimmers who had stopped high-level training, bronchial hyper responsiveness attenuated or even disappeared. On the other hand mild eosinophilic airway inflammation was aggravated among highly trained swimmers who remained active during the 5-year follow-up [17].

Diagnosing EIB in Athletes

The diagnosis of EIB is established by changes in lung function provoked by exercise, not on the basis of symptoms. Serial lung function measurements after a specific exercise or hyperpnea challenge are used to determine if EIB is present and to quantify the severity of the disorder. Forced Expiratory Volume in first second (FEV1) is used to diagnose this syndrome because this measurement has better repeatability and is more discriminating than peak expiratory flow rate. The airway response is expressed as the percent fall in FEV1 from the baseline value. The difference between the preexercise FEV1 value and the lowest FEV1 value recorded within 30 minutes after exercise is expressed as a percentage of the pre-exercise value. The criterion for the percent fall in FEV1 used to diagnose EIB is >10%. Several levels of EIB are described by American Thoracic Society (ATS) and are presented in Table 1 [1].

Table 1: Levels of EIB severity.




  
    Grade
    FEV1 fall
  
  
    Mild
    More than 10% but less than 25%
  
  
    Moderate
    More than 25% but less than 50%
  
  
    Severe
    More than 50%



Table 1:  Levels of EIB severity.

A number of surrogates for exercise testing have been developed that may be easier to implement than exercise challenge such as methacholine challenge, Eucapnic Voluntary Hyperpnoea (EVH) test, Field-Based Exercise Test (FBT) and a Laboratory-Based Exercise Test (LBT) but EVH test remains the most sensitive test for identifying EIB in elite athletes [1,18-22]. The International Olympic Committee has several recommendations for diagnosing EIB in athletes to permit the use of anti-asthmatic drugs: a positive clinical history and at least one positive diagnostic test (Table 2) [23].

Table 2: Diagnostic procedures for EIB and Asthma in athletes.




  
    Procedure 
    Criteria 
  
  
    Pulmonary function 
    FEV₁<70 %, FEV₁/VC <55 % 
  
  
    Bronchodilator test 
    ↑ FEV_ɪ?=?12 % and >200 ml 
  
  
    Eucapnic Voluntary Hyperpnea (EVH) 
    ↓ FEV_ɪ?=?10 % 
  
  
    Exercise challenge 
    ↓ FEV_ɪ?=?10 % 
  
  
    Methacholine challenge 
    ↓ FEV_ɪ?=?20 % with a:
      - PC₂₀?=?4 mg/ml (for subjects not taking ICS or
      - PC₂₀?=?16 mg/ml (for subjects taking    ICS for at least 1 month) 
  
  
    Hyperosmolar test (Mannitol, Saline) 
    ↓ FEV_ɪ?=?15 %



Table 2:  Diagnostic procedures for EIB and Asthma in athletes.

Since the pathogenesis of EIB in elite athletes might be different from that of asthma, the methacholine challenge test doesn’t always give the possibility to indentify EIB [21]. Other authors on the contrary recommend performing both methacholine challenge and EVH test in some groups of athletes since the exact mechanism of EIB is not completely understood and several factors may be involved in the development of this disease [24]. Finally another opinion exists that one EVH test is not enough and several tests should be performed especially in patients with borderline results to rule out possible misdiagnosis [25].

In general EVH is considered to be a more sensitive and specific test. A disadvantage is considered the need to monitor minute ventilation and that it is relatively expensive [26,27].

EVH should be also used as a screening method in athletes without EIB symptoms since not all athletes report having breathing difficulties but it can affect their performance and life quality [28]. Impulse oscillometry with indirect bronchoprovocation testing is another method for the diagnosis of airway dysfunction in athletes but it tends to detect additional cases of airway dysfunction in athletes [29].

In a study that involved 228 elite British athletes for EIB using EVH 78 athletes (34%) demonstrated EVH positive. Fifty seven out of the 78 (73%) athletes who demonstrated EVH positive did not have a previous diagnosis of EIB [30]. Of the 107 elite Tunisian athletes 1.8% reported previously having asthma but post-exercise spirometry revealed the presence of EIB in 14 (13%) of the athletes [31].

Additionally it should be noted that seasonal variability affects the occurrence of EIB, and thus exercise testing should be performed in both cold winter air and the pollen season to detect EIB in runners. Out of 58 elite runners, from Finnish national teams 9 (22%) of the 41 runners, challenged in both the winter and the pollen season, had probable EIB only in the winter, and 3 (7%) had it only in the pollen season whereas only one runner (2%) had EIB in both tests [32].

Management of EIB in Athletes

Several drugs are typically used in EIB such as Short-Acting Beta 2 Agonist (SABA), Long-Acting Beta 2 Agonists (LABA), Inhaled Corticosteroids (ICS), Leukotriene Receptor Antagonists (LRA), Mast Cell Stabilizing Agents (MCS) and Inhailed Anticholinergic Agents (IAA) and possibly also Antihistamines (AH) (Table 3) [1,33].

Download PDF

Citation: Covantev S, Corlateanu A and Botnaru V. Exercise-Induced Bronchoconstriction in Athletes. Austin J Pulm Respir Med 2016; 3(1): 1037. ISSN:2381-9022

Instruction for Authors

Submit Your Article

Grade	FEV1 fall
Mild	More than 10% but less than 25%
Moderate	More than 25% but less than 50%
Severe	More than 50%

Procedure	Criteria
Pulmonary function	FEV₁<70 %, FEV₁/VC <55 %
Bronchodilator test	↑ FEV_ɪ?=?12 % and >200 ml
Eucapnic Voluntary Hyperpnea (EVH)	↓ FEV_ɪ?=?10 %
Exercise challenge	↓ FEV_ɪ?=?10 %
Methacholine challenge	↓ FEV_ɪ?=?20 % with a: - PC₂₀?=?4 mg/ml (for subjects not taking ICS or - PC₂₀?=?16 mg/ml (for subjects taking ICS for at least 1 month)
Hyperosmolar test (Mannitol, Saline)	↓ FEV_ɪ?=?15 %

Drug	Administration	Recommendation	Level of evidence	2016 World Anti-Doping Agency (WADA) regulations
SABA	Before exercise	Strong	High-quality	Inhaled salbutamol (maximum 1600 �g over 24 hours)
LABA	Recommended against daily use as single therapy	Strong	Moderate-quality	Inhaled formoterol (maximum delivered dose 54 �g over 24 hours) and salmeterol in accordance with the manufacturers recommended therapeutic regimen
ICS	Recommended daily administration	Strong	Moderate-quality	Prohibited in competition
ICS	Recommended against administration only before exercise	Strong	Moderate-quality	Prohibited in competition
LRA	Recommended daily administration	Strong	Moderate-quality	Permitted
MCS	Before exercise	Strong	High-quality	Permitted
IAA	Before exercise	Weak	Low-quality	Permitted
AH	If symptoms persist despite using an inhaled SABA before exercise, or if the patient require an inhaled SABA daily or more frequently	Weak	Moderate-quality	Permitted
AH	Recommended against administration in patients who do not have allergies	Strong	Moderate-quality	Permitted