Exercise-induced bronchospasm in the elite athlete

Unique Medical Considerations for the Athlete Undergoing Anesthesia

Athletes are among a unique group such that they may possess a serious underlying pathologic condition that may often go unnoticed given their high caliber of physical fitness. However, several considerations should be investigated, especially in the perioperative period, in order to minimize morbidity and mortality. Namely, cardiac pathologic condition can result in sudden death, and pulmonary pathologic condition may affect airway and respiratory management. Moreover, patients undergoing orthopedic surgery are at the highest risk for venous thromboembolism. Regardless of the condition, it is crucial to be vigilant and explore the unique medical considerations for the athlete undergoing anesthesia.

Designing and validating an experimental protocol to induce airway narrowing in older adults with and without asthma

BACKGROUND

Persons with asthma may experience excessive airway narrowing due to exercise or exposure to cold air, worsening their daily functionality. Exercise has several benefits for asthma control, but it may induce airway narrowing in some persons with asthma. When combined with cold temperatures, it introduces another layer of challenges. Therefore, managing this interaction is crucial to increase the quality of life in individuals with asthma. The purpose of this study was to develop a reliable experimental protocol to assess the effects of exercise and cold air on airway narrowing in adults with asthma in a controlled and safe environment.

METHODS

This study was a randomized cross-over study in adults with and without asthma. Participants underwent a protocol involving a 10-min seated rest, followed by a 10-min cycling on a stationary bike in different temperatures of 0, 10, or 20 ∘ C. The sequence of room temperatures was randomized, and there was a 30-min interval for recovery between each temperature transition. In each temperature, to measure lung function and respiratory symptoms, oscillometry and a questionnaire were used at 0 min (baseline), after 10 min of sitting and before starting biking (pre-exercise), and after 10 min of biking (post-exercise). At each room temperature, the changes in airway mechanics and asthma symptoms among baseline, pre-exercise, and post-exercise were compared with one-way repeated measures ANOVA or Friedman Rank Test. Within each arm, cardiac and thoraco-abdominal motion respiration signals were also measured continuously using electrodes and calibrated respiratory inductance plethysmographs, respectively.

RESULTS

A total of 23 persons with asthma (11 females, age: 56.3 ± 10.9 years, BMI: 27.4 ± 5.7 kg/m2) and 6 healthy subjects (3 females, age: 61.8 ± 9.1 years, BMI: 28.5 ± 3.1 kg/m2) were enrolled in the study. Cold temperature of 0∘ C induced airway narrowing in those with and without asthma after 10 and 20 min, respectively. Exercise intervention had significant changes in airway narrowing in participants with asthma in the range of 10-20∘ C. Our results showed that in asthma, changes in subjective respiratory symptoms were due to both cold temperatures of 0 and 10∘ C and exercise in the 0-20∘ C range. Respiratory symptoms were not noticed among the healthy participants.

CONCLUSION

In conclusion, our findings suggest that exposure to cold temperatures of 0∘ C could serve as a reliable method in the experimental protocol for inducing airway narrowing in asthma. The impact of exercise on airway narrowing was more variable among participants. Understanding these triggers in the experimental protocol is essential for the successful management of asthma in future studies.

Influence of the breathing pattern on the pulmonary function of endurance-trained athletes

Proper functioning of the respiratory system is one of the most important determinants of human health. According to current knowledge, the diaphragmatic breathing pattern seems to be the most favourable. However, recent reports indicate that athletes often have dysfunctional breathing patterns, which may be associated with an increased risk of musculoskeletal injuries. The influence of the type of breathing pattern on the mechanical airways in athletes has not been investigated. The aim of the present study was to determine the characteristics and relationships between breathing patterns and respiratory function in athletes. This study included 69 Polish elite endurance athletes (♂40, ♀29) in different sports disciplines and 44 (♂17, ♀27) healthy nonathletes as a control group. All participants underwent pulmonary function tests (spirometry, plethysmography, diffusion capacity for carbon monoxide) with assessment of breathing patterns by the Hi-Lo test. Inspiratory and expiratory resistance (R) and reactance (X) of the respiratory system at a given frequency (5 Hz, 11 Hz, and 19 Hz) were measured by a noninvasive forced oscillation technique. In this study, almost half of the athletes (44.92%) had dysfunctional breathing patterns, although at a lower rate than that in the control group. Diaphragmatic breathing patterns were characterized by higher spirometric, plethysmographic and DLCO values compared to thoracic or abdominal breathing patterns. Similarly, lower inspiratory reactance at 5 Hz (X5%pred.) was observed in the diaphragmatic pattern compared to the thoracic pattern. A diaphragmatic breathing pattern is associated with better pulmonary function test results. However, this study revealed a dysfunctional breathing pattern in almost half of the athletes. These results suggest that the assessment of breathing patterns and the implementation of breathing exercises in athletes are essential to promote proper breathing patterns.

Acute Effects of Single Versus Combined Inhaled β2-Agonists Salbutamol and Formoterol on Time Trial Performance, Lung Function, Metabolic and Endocrine Variables

BACKGROUND

High prevalence rates of β2-agonist use among athletes in competitive sports makes it tempting to speculate that illegitimate use of β2-agonists boosts performance. However, data regarding the potential performance-enhancing effects of inhaled β2-agonists and its underlying molecular basis are scarce.

METHODS

In total, 24 competitive endurance athletes (12f/12m) participated in a clinical double-blinded balanced four-way block cross-over trial to investigate single versus combined effects of β2-agonists salbutamol (SAL) and formoterol (FOR), to evaluate the potential performance enhancement of SAL (1200 µg, Cyclocaps, Pb Pharma GmbH), FOR (36 µg, Sandoz, HEXAL AG) and SAL + FOR (1200 µg + 36 µg) compared to placebo (PLA, Gelatine capsules containing lactose monohydrate, Pharmacy of the University Hospital Ulm). Measurements included skeletal muscle gene and protein expression, endocrine regulation, urinary/serum β2-agonist concentrations, cardiac markers, cardiopulmonary and lung function testing and the 10-min time trial (TT) performance on a bicycle ergometer as outcome variables. Blood and urine samples were collected pre-, post-, 3 h post- and 24 h post-TT.

RESULTS

Mean power output during TT was not different between study arms. Treatment effects regarding lung function (p < 0.001), echocardiographic (left ventricular end-systolic volume p = 0.037; endocardial global longitudinal strain p < 0.001) and metabolic variables (e.g. NR4A2 and ATF3 pathway) were observed without any influence on performance. In female athletes, total serum β2-agonist concentrations for SAL and FOR were higher. Microarray muscle gene analysis showed a treatment effect for target genes in energy metabolism with strongest effect by SAL + FOR (NR4A2; p = 0.001). Of endocrine variables, follicle-stimulating hormone (3 h Post-Post-TT), luteinizing hormone (3 h Post-Pre-TT) and insulin (Post-Pre-TT) concentrations showed a treatment effect (all p < 0.05).

CONCLUSIONS

No endurance performance-enhancing effect for SAL, FOR or SAL + FOR within the permitted dosages compared to PLA was found despite an acute effect on lung and cardiac function as well as endocrine and metabolic variables in healthy participants. The impact of combined β2-agonists on performance and sex-specific thresholds on the molecular and cardiac level and their potential long-term performance enhancing or health effects have still to be determined.

TRIAL REGISTRATION

Registered at Eudra CT with the number: 2015-005598-19 (09.12.2015) and DRKS with number DRKS00010574 (16.11.2021, retrospectively registered).

Effect of Omega-3 Polyunsaturated Fatty Acids Intake on Eosinophil Airway Inflammation in University Athletes

Background

Though athletes have a high risk of respiratory disorders, effective prevention has not yet to be identified. Omega-3 (n-3) polyunsaturated fatty acids (PUFA) have some practical anti-inflammatory effects in allergy, and therefore may reduce airway inflammation in athletes. This study aimed to assess whether n-3 PUFA intake affects airway inflammation in university athletes.

Methods

Twenty-three males were divided into three groups: 1) the eosinophilic airway inflammation group (I_PUFA group; fractional exhaled nitric oxide (FeNO ≥ 25 ppb, n = 10); 2) the non-eosinophilic airway inflammation group (N_PUFA group; FeNO < 25 ppb, exhaled carbon dioxide (eCO) ≥ 3.6 ppm, n = 5); and 3) the control group (FeNO < 25 ppb, eCO < 3.6 ppm, n = 8). Participants took supplements containing 260 mg of docosapentaenoic acid and 600 mg of eicosapentaenoic acid (EPA) daily for 3 weeks. Baseline measurements of FeNO, respiratory impedance, respiratory function, dietary intake (food frequency questionnaires), and blood tests were performed. FeNO and respiratory impedance were measured weekly, and the rest were measured after 3 weeks.

Results

There was a significant decrease in FeNO levels from baseline at 2 and 3 weeks in the I_PUFA group (54.7 ± 8.5 ppb vs. 45.1 ± 9.1 and 45.4 ± 7.7 ppb; mean ± standard error (SE), P < 0.05). After 3 weeks, FeNO levels remained unchanged in the N_PUFA and control groups, and respiratory impedance and function remained unchanged in all groups. Blood EPA levels significantly increased in the I_PUFA and N_PUFA groups (I_PUFA, 27.7 ± 16.9 vs. 52.1 ± 12.3 µg/mL; N_PUFA, 20.8 ± 8.7 vs. 70.4 ± 36.1 µg/mL; mean ± standard deviation (SD), P < 0.05). No changes were observed in dietary intake over the 3 weeks.

Conclusions

n-3 PUFA supplementation for 3 weeks reduced airway inflammation in athletes with FeNO levels ≥ 25 ppb.

International Olympic Committee (IOC) consensus statement on acute respiratory illness in athletes part 2: non-infective acute respiratory illness

Acute respiratory illness (ARill) is common and threatens the health of athletes. ARill in athletes forms a significant component of the work of Sport and Exercise Medicine (SEM) clinicians. The aim of this consensus is to provide the SEM clinician with an overview and practical clinical approach to non-infective ARill in athletes. The International Olympic Committee (IOC) Medical and Scientific Committee appointed an international consensus group to review ARill in athletes. Key areas of ARill in athletes were originally identified and six subgroups of the IOC Consensus group established to review the following aspects: (1) epidemiology/risk factors for ARill, (2) infective ARill, (3) non-infective ARill, (4) acute asthma/exercise-induced bronchoconstriction and related conditions, (5) effects of ARill on exercise/sports performance, medical complications/return-to-sport (RTS) and (6) acute nasal/laryngeal obstruction presenting as ARill. Following several reviews conducted by subgroups, the sections of the consensus documents were allocated to 'core' members for drafting and internal review. An advanced draft of the consensus document was discussed during a meeting of the main consensus core group, and final edits were completed prior to submission of the manuscript. This document (part 2) of this consensus focuses on respiratory conditions causing non-infective ARill in athletes. These include non-inflammatory obstructive nasal, laryngeal, tracheal or bronchial conditions or non-infective inflammatory conditions of the respiratory epithelium that affect the upper and/or lower airways, frequently as a continuum. The following aspects of more common as well as lesser-known non-infective ARill in athletes are reviewed: epidemiology, risk factors, pathology/pathophysiology, clinical presentation and diagnosis, management, prevention, medical considerations and risks of illness during exercise, effects of illness on exercise/sports performance and RTS guidelines.

Unique Medical Considerations for the Athlete Undergoing Anesthesia

Athletes are among a unique group such that they may possess a serious underlying pathologic condition that may often go unnoticed given their high caliber of physical fitness. However, several considerations should be investigated, especially in the perioperative period, in order to minimize morbidity and mortality. Namely, cardiac pathologic condition can result in sudden death, and pulmonary pathologic condition may affect airway and respiratory management. Moreover, patients undergoing orthopedic surgery are at the highest risk for venous thromboembolism. Regardless of the condition, it is crucial to be vigilant and explore the unique medical considerations for the athlete undergoing anesthesia.

The ELSA trial: single versus combinatory effects of non-prohibited beta-2 agonists on skeletal muscle metabolism, cardio-pulmonary function and endurance performance-study protocol for a randomized 4-way balanced cross-over trial

BACKGROUND

Asthma and/or airway hyper-responsiveness (AHR) are common in elite endurance athletes with a high prevalence rate of beta-2 adrenoreceptor (beta-2) agonists use. Nevertheless, there are data on dose-dependent ergogenic effects of beta-2 agonists suggesting increased muscle strength, endurance and neuromuscular performance. Therefore, most beta-2 agonists belong to the World Anti Doping Agency (WADA) list of prohibited substances and it is tempting to speculate that illegitimate use of beta-2 agonists might be a common practice to boost performance in competitive sports. It is currently unknown whether or not inhaled beta-2 agonists enhance performance by stimulatory effects in skeletal and cardiac muscle.

METHODS

The ELSA trial is a double-blinded, placebo-controlled, randomized, balanced, four-way cross-over study. Study participants (n=24, 12 ♀, 12 ♂) complete four study arms (i.e. periods with treatment A, placebo; B, salbutamol; C, formoterol; D, formoterol + salbutamol) in random order after an initial preliminary testing session. Participants inhale the study medication 20 min before the 10-min time trial (TT; exercise performance test), where participants cycle 10 min at the highest possible workload. Cardiac output is measured continuously. A skeletal muscle biopsy is collected 3 h after the TT. Study endpoints include measures of skeletal muscle expression of nuclear receptors, hormones and cytokine levels, urinary and plasma concentrations of salbutamol and formoterol, circulating cardiac markers, cardiopulmonary function and exercise performance (average power and peak power during the TT). Blood and urine are collected and respiratory testing is performed 24 h post TT. This clinical trial evaluates the potential performance-enhancing effects of non-prohibited, not medically indicated inhaled short- and long-acting beta-2 agonists on skeletal muscle gene expression, endocrine regulation, cardiac biomarkers, cardiopulmonary function and acute endurance exercise performance. These data will be used by WADA to adapt the annually published list of prohibited substances (WADA 2021) and will be published in scientific journals.

TRIAL REGISTRATION

The trial is registered at the European Clinical Trials Database (Eudra CT) with the number: 2015-005598-19 as well as at the German register for clinical studies (DRKS number 00010574 ).

Characteristics and impact of exercise-induced laryngeal obstruction: an international perspective

Background

Exercise-induced laryngeal obstruction (EILO) is a common cause of exertional breathlessness and wheeze yet is frequently misdiagnosed as asthma. Insight regarding the demographic characteristics, laryngeal abnormalities and impact of EILO is currently limited, with data only available from individual centre reports. The aim of this work was to provide a broader perspective from a collaboration between multiple international expert centres.

Methods

Five geographically distinct clinical paediatric and adult centres (3 Denmark, 1 UK, 1 USA) with an expertise in assessing unexplained exertional breathlessness completed database entry of key characteristic features for all cases referred with suspected EILO over a 5-year period. All included cases completed clinical asthma workup and continuous laryngoscopy during exercise (CLE) testing for EILO.

Results

Data were available for 1007 individuals (n=713 female (71%)) with a median (range) age of 24 (8–76) years, and of these 586 (58%) were diagnosed with EILO. In all centres, EILO was frequently misdiagnosed as asthma; on average there was a 2-year delay to diagnosis of EILO, and current asthma medication was discontinued in 20%. Collapse at the supraglottic level was seen in 60%, whereas vocal cord dysfunction (VCD) was only detected/visualised in 18%. Nearly half (45%) of individuals with EILO were active participants in recreational-level sports, suggesting that EILO is not simply confined to competitive/elite athletes.

Conclusion

Our findings indicate that key clinical characteristics and the impact of EILO/VCD are similar in globally distinct regions, facilitating improved awareness of this condition to enhance recognition and avoid erroneous asthma treatment.

Exercise-induced laryngeal obstruction is a prevalent cause of exertional breathlessness and wheeze. In this international multicentre collaboration, 1007 patients waited, on average, 2 years for diagnosis and 20% were mistreated as asthmatic.https://bit.ly/3auXpcp

Salivary IL-8 and IL-1RA changes induced by exercise in cold-dry and normal conditions

The purpose of this study was to compare the effects of exercise in cold-dry (CC, -20 °C, RH 40%) and normal conditions (NC, 20 °C, RH 60%) on salivary levels of pro-inflammatory and regulatory cytokines (IL-1RA, IL-8, and IL-5) and the airway response (FEV₁ and FVC) in young healthy males. Participants (n = 11, age: 23.6 ± 3.1 years) completed an incremental to maximal exercise test and two exercise sessions in an environmental chamber in random order. Saliva samples were collected, and spirometry was performed prior to the maximal exercise test as well as pre and post-exercise for the CC and NC sessions. IL-8 levels increased from pre to post-exercise during NC but not during CC; the opposite trend was observed for IL-1RA. These data may provide insight into pathways associated with the development of airway hyperresponsiveness in healthy athletes.

Cysteinyl Leukotriene Synthesis via Phospholipase A2 Group IV Mediates Exercise-induced Bronchoconstriction and Airway Remodeling

It is well known that the prevalence of asthma is higher in athletes, including Olympic athletes, than in the general population. In this study, we analyzed the mechanism of exercise-induced bronchoconstriction by using animal models of athlete asthma. Mice were made to exercise on a treadmill for a total duration of 1 week, 3 weeks, or 5 weeks. We analyzed airway responsiveness, BAL fluid, lung homogenates, and tissue histology for each period. In mice that were treated (i.e., the treatment model), treatments were administered from the fourth to the fifth week. We also collected induced sputum from human athletes with asthma and analyzed the supernatants. Airway responsiveness to methacholine was enhanced with repeated exercise stimulation, although the cell composition in BAL fluid did not change. Exercise induced hypertrophy of airway smooth muscle and subepithelial collagen deposition. Cysteinyl-leukotriene (Cys-LT) levels were significantly increased with exercise duration. Montelukast treatment significantly reduced airway hyperresponsiveness (AHR) and airway remodeling. Expression of PLA₂G4 (phospholipase A₂ group IV) and leukotriene C₄ synthase in the airway epithelium was upregulated in the exercise model, and inhibition of PLA₂ ameliorated AHR and airway remodeling, with associated lower levels of Cys-LTs. The levels of Cys-LTs in sputum from athletes did not differ between those with and without sputum eosinophilia. These data suggest that AHR and airway remodeling were caused by repeated and strenuous exercise. Cys-LTs from the airway epithelium, but not inflammatory cells, may play an important role in this mouse model.

Work Group Report: Perspectives in Diagnosis and Management of Exercise-Induced Bronchoconstriction in Athletes

Exercise-induced bronchoconstriction, otherwise known as exercise-induced bronchoconstriction with asthma or without asthma, is an acute airway narrowing that occurs as a result of exercise and can occur in patients with asthma. A panel of members from the American Academy of Allergy, Asthma & Immunology Sports, Exercise, & Fitness Committee reviewed the diagnosis and management of exercise-induced bronchoconstriction in athletes of all skill levels including recreational athletes, high school and college athletes, and professional athletes. A special emphasis was placed on the recommendations and regulations set forth by professional athletic organizations after a detailed review of their collective bargaining agreements, substance abuse policies, antidoping program manuals, and the World Anti-Doping Agency antidoping code. The recommendations in this review are based on currently available evidence in addition to providing guidance for athletes of all skill levels as well as their treating physicians to better understand which pharmaceutical and nonpharmaceutical management options are appropriate as well as which medications are permitted or prohibited, and the proper documentation required to remain compliant.

Heating-induced contraction in airways smooth muscle: A possible causative factor of exercise-induced bronchoconstriction

Asthmatic patients often suffer from bronchoconstriction or asthma following breathing hot air or exposure to exercise due to raises the core body temperature. However, the direct effect of heating airways has not been studied yet. The aim of this study is to investigate the effect of heating on tracheal and bronchiolar smooth muscles. Isolated ovine tracheal strips and bronchiolar segments preparations were suspended in organ baths containing Krebs' solution for isometric tension recording. Tissues responses were examined during decreasing and elevating baths temperature (20 °C, 40 °C-45 °C and 50 °C). Cooling or heating induced rapid and reproducible contractions proportional with decreasing or increasing temperature respectively in tracheal and bronchiolar preparations. On reset to 37 °C the tone returned rapidly to basal level. Changing the bath's temperature from 37 °C to 20 °C or to 40 °C and 45 °C for tracheal strips or to 45 °C and 50 °C for bronchiolar segments induced contractions in both preparations. Changing the temperature below or above the normal body temperature (37 °C), leads to airways contractions. Heating induced contractions in tracheal and bronchiolar smooth muscle proportional to the heating temperature. Therefore, breathing hot air or elevation of body core temperature due to exercise can be considered possible causative factor of heating- or exercise-induced bronchoconstriction.

Exercise performance after salbutamol inhalation in non-asthmatic, non-athlete individuals: a randomised, controlled, cross-over trial

Background

Asthma is a frequent diagnosis in competitive sports, and inhaled β₂-agonists are commonly used by athletes. Although inhaled β₂-agonists do not seem to improve performance in athletes, it has remained uncertain whether they can increase exercise performance in non-athletes.

Objective

To investigate the effect of inhaled β₂-agonists on exercise performance in healthy non-athlete individuals.

Methods

In a double-blinded, placebo-controlled, cross-over trial, healthy, non-asthmatic, non-athlete individuals were randomised to inhalation of either 900 µg of salbutamol or placebo. Cardiopulmonary exercise testing, dynamic spirometry and impulse oscillometry were performed. The primary outcome was the effect from salbutamol on peak oxygen uptake, whereas secondary outcomes were breathing reserve and ventilation efficiency, and workload, heart rate, breath rate and minute ventilation at peak exercise under influence of salbutamol.

Results

A total of 36 healthy subjects with a mean age of 26±5 years were included. Salbutamol had no effect on peak oxygen uptake compared with placebo, 46.8±1.3 mL/kg/min versus 46.6±1.2 mL/kg/min, p=0.64. Salbutamol had no effect on workload, p=0.20, heart rate, p=0.23, breath rate, p=0.10, or minute ventilation, p=0.26, at peak exercise compared with placebo. Salbutamol lowered oxygen uptake, p=0.04, and workload, p=0.04, at anaerobic threshold compared with placebo. Forced expiratory volume in 1 s, 116%±13% of predicted, and peak expiratory flow, 122%±16% of predicted, increased after inhalation of salbutamol compared with placebo; 109%±13% and 117%±17%, respectively, p<0.01. Breathing reserve was found to be higher, 22%±2%, after salbutamol inhalation than after placebo, 16%±2%, p<0.01.

Conclusion

Inhaled salbutamol did not improve peak oxygen uptake in healthy, non-asthmatic, non-athlete individuals compared with placebo.

Trial registration number

NCT02914652.

Evaluating the Athlete with Suspected Exercise-Induced Asthma or Bronchospasm

Exercise-induced asthma (EIA) and exercise-induced bronchospasm (EIB)/bronchoconstriction (EIC) describes two clinical entities by which exercise triggers bronchial hyperresponsiveness. Exercise is a common trigger of bronchospasm in the asthmatic (EIA), as well as athletes without the underlying inflammation associated with asthma (EIC/EIB). Approximately 10% to 20% of the general population have EIA or EIB (). The approach to the diagnosis and subsequent management relies on the clinician's ability to recognize clinical signs and symptoms, then selecting the correct diagnostic test. A baseline spirometry/pulmonary function test is recommended for all athletes to evaluate for underlying asthma. Subsequent direct or indirect bronchial provocation testing is recommended to correctly diagnose EIA or EIB (). Athletes should not be treated empirically with bronchodilators based on symptoms alone without confirmatory spirometry and provocative testing.

Phenotypic analysis of asthma in Japanese athletes

BACKGROUND

Asthma in athlete populations such as Olympic athletes has various pathogeneses. However, few reports are available on the features of asthma in the athlete population in clinical practice. In this study, we focused on classifying asthma in Japanese athlete population.

METHODS

We performed a cluster analysis of data from pulmonary function tests and clinical biomarkers before administering inhaled corticosteroids (ICS) therapy in athlete population of individuals diagnosed with asthma (n = 104; male, 76.9%; median age, 16.0 years), based on respiratory symptoms and positive data on methacholine provocation tests. We also compared backgrounds, sports types, and treatments between clusters.

RESULTS

Three clusters were identified. Cluster 1 (32%) comprised athletes with a less atopic phenotype and normal pulmonary function. Cluster 2 (44%) comprised athletes with a less atopic phenotype and lower percent predicted forced expiratory volume in 1 s (%FEV₁) values, despite less symptomatic state. Cluster 3 (24%) comprised athletes with a strong atopic phenotype such as high eosinophil count in the blood and total serum immunoglobulin E level. After treatment with ICS or ICS plus long-acting β-adrenergic receptor agonist for 6-12 months, %FEV₁ values were significantly improved in Cluster 2 athletes, whereas Cluster 3 athletes had a significant decrease in the fraction of exhaled nitric oxide compared to pretreatment values.

CONCLUSIONS

These data suggest three clusters exist in Japanese athlete population with asthma. Between the clusters, the characteristics differed with regard to symptoms, atopic features, and lower %FEV₁ values. The pathogeneses between clusters may vary depending on the inflammation type and airway hyperresponsiveness.

Cellular Na+ handling mechanisms involved in airway smooth muscle contraction (Review)

A decrease in bronchial diameter is designated as bronchoconstriction (BC) and impedes the flow of air through the airway. Asthma is characterized by inflammation of the airways, reversible BC and nonspecific hyperreactivity. These last two symptoms are dependent on airway smooth muscle. Stimuli that trigger contraction can be characterized as chemical (neurotransmitters, cytokines and terpenoids) and physical (volume inspired, air pressure). Both stimuli activate signaling pathways by acting on membrane proteins and facilitating the passage of ions through the membrane, generating a voltage change and a subsequent depolarization. Na⁺ plays an important role in preserving the resting membrane potential; this ion is extracted from the cells by the Na⁺/K⁺ ATPase (NKA) or introduced into the cytoplasm by the Na⁺/Ca²⁺ exchanger (NCX). During depolarization, Na⁺ appears to accumulate in specific regions beneath the plasma membrane, generating local concentration gradients which determine the handling of Ca²⁺. At rest, the smooth muscle has a basal tone that is preserved by the continuous adjustment of intracytoplasmic concentrations of Ca²⁺ and Na⁺. At homeostasis, the Na⁺ concentration is primarily dependent on three structures: the NKA, the NCX and non-specific cation channels (NSCC). These three structures, their functions and the available evidence of the probable role of Na⁺ in asthma are described in the present review.

Sociodemographic, health-related and lifestyle correlates of physical activity in adults with current asthma

OBJECTIVE

Regular physical activity is associated with better asthma control; however, little is known of the determinants of physical activity in a population of adults with asthma. Thus, the purpose of this study was to identify important sociodemographic, health and lifestyle correlates of physical activity among adults with asthma.

METHODS

Data from adults with asthma aged 18-44 years (n = 2740) from the Canadian Community Health Survey (CCHS), 2011-2012 annual component were used for analysis. The main outcome was Daily Energy Expenditure (DEE). This variable was based on frequency and duration of leisure activities in the past 3 months. Self-reported sociodemographic (age, sex, total household income, highest education level, and ethnicity), health-related (body mass index (BMI), self-perceived health, mood disorder, anxiety disorder, and asthma symptoms/attacks, past year) and lifestyle (type of smoker, sedentary time, fruit and vegetable consumption) variables were assessed as correlates for DEE. Data were analysed using linear regressions.

RESULTS

In the final model, sociodemographic correlates accounted for 4.2% of the variation in DEE. Adding health correlates increased the R² to 12.1%. Finally, adding lifestyle correlates increased the R² to 17.6%.

CONCLUSIONS

In adults with current asthma, the main correlates of physical activity are age, total household income, BMI, self-perceived health, anxiety disorder, sedentary time, and fruit and vegetable consumption. These data are important for informing education and exercise interventions for adults with asthma. Future research is needed to determine asthma-specific correlates of physical activity.

Medical Evaluation for Exposure Extremes: Cold

Risk of injury in cold environments is related to a combination of athlete preparedness, preexisting medical conditions, and the body's physiologic response to environmental factors, including ambient temperature, windchill, and wetness. The goal of this section is to decrease the risk of hypothermia, frostbite, and nonfreezing cold injuries as well as to prevent worsening of preexisting conditions in cold environments using a preparticipation screening history, examination, and counseling. Cold weather exercise can be done safely with education, proper preparation, and appropriate response to changing weather conditions.

Effect of inhaled corticosteroids on bronchial asthma in Japanese athletes

BACKGROUND

Asthma has a higher prevalence in athlete populations such as Olympic athletes than in the general population. Correct diagnosis and management of asthma in athletes is important for symptom control and avoidance of doping accusations. However, few reports are available on asthma treatment in the athlete population in clinical practice. In this study, we focused on the clinical efficacy of inhaled corticosteroid (ICS) for asthma in a Japanese athlete population.

METHODS

The study subjects included athletes who visited the Niigata Institute for Health and Sports Medicine, Niigata, Japan for athletic tests and who were diagnosed with asthma on the basis of respiratory symptoms and positive results in a bronchodilator or bronchial provocation test such as exercise, hypertonic saline, or methacholine provocation. The athletes received ICS alone for at least 3 months, and the clinical background, sports type, and treatment efficacy were analyzed.

RESULTS

The study population comprised 80 athletes (59 men and 21 women) with a median age of 16.0 years. Regarding sports type, 28 athletes engaged in winter sports (35%), 22 in endurance sports (27.5%), and 25 in indoor sports (31.3%). Although ICS is the primary treatment in athlete asthma, 16.3% of the athletes showed an unsatisfactory response to treatment according to the Global Evaluation of Treatment Effectiveness (GETE). These subjects were characterized by a decreased response to methacholine and lower values for FEV1/FVC and type 2 helper T cell (Th2)-associated biomarkers relative to responsive athletes. In multivariate analysis, FEV1/FVC and the logarithm to the base 10 of the IgE level were independently associated with the ICS response.

CONCLUSIONS

These data suggest that ICS is effective for asthma in most athletes. However, certain asthmatic athletes are less responsive to ICS than expected. The pathogenesis in these subjects may differ from that of conventional asthma characterized by chronic allergic airway inflammation.

Airway dysfunction in elite athletes--an occupational lung disease?

Airway dysfunction is prevalent in elite endurance athletes and when left untreated may impact upon both health and performance. There is now concern that the intensity of hyperpnoea necessitated by exercise at an elite level may be detrimental for an athlete's respiratory health. This article addresses the evidence of causality in this context with the aim of specifically addressing whether airway dysfunction in elite athletes should be classified as an occupational lung disease. The approach used highlights a number of concerns and facilitates recommendations to ensure airway health is maintained and optimized in this population. We conclude that elite athletes should receive the same considerations for their airway health as others with potential and relevant occupational exposures.

Exercise-induced bronchoconstriction

Exercise-induced bronchoconstriction (EIB) occurs commonly in patients with asthma but also can affect individuals without asthma. EIB is particularly common in populations of athletes. Common symptoms include cough, dyspnea, chest tightness, and wheezing; however, there can be a variety of more subtle symptoms. In this article, the clinical presentation of EIB as well as the diagnosis and treatment of EIB are outlined.

Immunopathology of exercise-induced bronchoconstriction in athletes--a new modified inflammatory hypothesis

Elite athletes have a higher prevalence of exercise-induced bronchoconstriction than the general population. The pathogenesis of exercise-induced bronchoconstriction is not fully elucidated. Increasing evidence suggests that airway inflammation plays a major role in the immunopathogenesis of exercise-induced bronchoconstriction. The aim of our review is to discuss existing evidence and to present a new, modified inflammatory hypothesis of exercise-induced bronchoconstriction. Exercise alters the number and function of circulating immune cells. Episodes of upper respiratory symptoms in elite athletes do not follow the usual seasonal patterns. Moreover, they have an unusual short-term duration, which suggests a non-infectious etiology. If the pro-inflammatory response to exercise has the potential to induce symptoms that mimic respiratory tract infection, it definitely up-regulates pro-inflammatory cytokine expression in the airways. We can conclude that exercise up-regulates airway cytokine expression in a way that favors inflammation and allergic reactions in bronchi and lowers the threshold for bronchoconstriction to different stimuli like cool, dry air, allergens, and pollutants.

Special considerations for adolescent athletic and asthmatic patients

Asthma is defined as a chronic inflammatory disorder of the airways with bronchial hyperresponsiveness and variable bronchoconstriction, and is one of the most common diseases in childhood and adolescence. Exercise-induced asthma-like symptoms and asthma are also frequently seen in highly trained athletes. Exercise-induced asthma (EIA) and exercise-induced bronchoconstriction (EIB) are found in 8%–10% of healthy school-aged children and in 35% of children with asthma. Highly increased ventilation, inhalation of cold, dry air and air pollutants (eg, chlorine) are thought to be important triggers for EIA and EIB. EIA is often experienced concurrently with vocal cord dysfunction, which needs to be considered during the differential diagnosis. The pharmacological treatment of EIA is similar to the treatment of asthma in nonexercising adolescents. The therapy is based on anti-inflammatory drugs (eg, inhaled glucocorticosteroids) and bronchodilators (eg, β₂-agonists). The treatment of EIB is comparable to the treatment of EIA and leukotriene modifiers offer a new and promising treatment option, particularly in EIB. Generally, athletes may not use β₂-agonists according to the prohibited list of the World Anti-Doping Agency (WADA). However, the WADA list contains specific β₂-agonistic substances that are permitted to be used by inhalation.

How to diagnose exercise induced asthma?

Exercise induced asthma (EIA) is a transient increase in airway resistance after intensive exercise and can be measured as a decline in forced expiratory volume in one second (FEV1). The condition is due to increased training load and inhalation of cold and dry air. Several studies have shown that eucapnic voluntary hyperpnea challenge test (EVH test) is a very sensitive and specific diagnostic method. EVH test develops EIA by hyperventilation of dry gas and the test achieves the same airway obstruction as training in cold and dry air. The test is better than the previously used methacholine challenge test.

Etiology of dyspnea in elite and recreational athletes

BACKGROUND

Breathing complaints are common in athletes. Studies have suggested that the prevalence of asthma and exercise-induced bronchoconstriction (EIB) is higher in elite athletes than the general population. Vocal cord dysfunction (VCD) may mimic asthma and EIB as a cause of dyspnea in athletes. However, the majority of studies to date have primarily relied on symptoms to diagnose VCD, and there are limited data on coexistence of asthma, EIB, and/or VCD. It is well established that symptoms alone are inadequate to accurately diagnose EIB and VCD. Our goal was to define via objective testing the prevalence of asthma, EIB, VCD alone, or in combination in a cohort of athletes with respiratory complaints.

METHODS

A retrospective chart review was done of 148 consecutive athletes (collegiate, middle school, high school, and recreational) referred to a tertiary care center's asthma center for evaluation of respiratory complaints with exercise. An evaluation including medical history, physical examination, and objective testing including pulmonary function testing (PFT), eucapnic voluntary hyperventilation, and video laryngostroboscopy, were performed.

RESULTS

The most common symptom was dyspnea on exertion (96%), with < 1% complaining of either hoarseness or stridor. The most common diagnosis prior to referral was asthma (40%). Only 16% had PFTs prior to referral. Following evaluation by a pulmonologist, 52% were diagnosed with EIB, 17% with asthma, and 70% with VCD. Of those diagnosed with asthma before our evaluation, the diagnosis of asthma was confirmed, with PFTs in only 19 of 59 (32%) athletes based on our testing. Vocal cord dysfunction was more common in females and in adolescent athletes. Coexistence of multiple disorders was common, such as EIB and asthma (8%), EIB and VCD (31%), and VCD and asthma (6%).

CONCLUSIONS

Asthma and EIB are common etiologies of dyspnea in athletes, both competitive and recreational. However, VCD is also common and can coexist with either asthma or EIB. Vocal cord dysfunction may contribute to exercise-related respiratory symptoms more frequently in middle school- and high school-aged athletes than in college athletes. Effective treatment of dyspnea requires appropriate identification and treatment of all disorders. Classic symptoms of stridor and/or hoarseness are often not present in athletes with VCD. Accurate diagnosis of asthma, EIB, and VCD requires objective testing and can prevent exposure of patients to medications that are ineffective and have potential adverse side effects. Furthermore, there is need for increased awareness of VCD as a common cause of respiratory complaints in athletes, either as a single diagnosis or in combination with EIB, especially in females, as well as middle school and high school athletes.

Mechanisms and management of exercise-induced asthma in elite athletes

OBJECTIVE AND METHODS

Asthma is often reported by elite athletes, especially endurance athletes. The aim of this article is to review current knowledge of mechanisms and management of exercise-induced asthma (EIA) in adult elite athletes.

RESULTS

The mechanisms underlying EIA is incompletely understood, but the two prevailing hypotheses are the hyper-osmolarity and the thermal hypothesis. Both hypotheses consider inflammation and activation of mast cells as being crucial for the development of EIA, although the assumed mechanisms triggering the inflammatory response differ. Objective testing is of utmost importance in the diagnosis of EIA in elite athletes. Management of EIA can be divided into pharmacologic and non-pharmacologic treatment. The basic principles for the treatment of EIA in elite athletes should be as for any asthmatic individual, including use of inhaled corticosteroids (ICS), β(2)-agonists, and leukotriene antagonists. However, evidence suggests that daily use of β(2)-agonists might lead to the development of tolerance. ICS therapy is, due to its anti-inflammatory effects, the recommended primary therapy for EIA also in elite athletes. All doctors treating individuals with asthma, especially elite athletes, should remain updated on doping aspects of asthma therapy. Non-pharmacologic management of EIA in elite athletes includes physical warm-up, which takes advantage of the refractory period following an attack of EIA, whereas high intake of antioxidants may reduce airway inflammation. Wearing heat masks, specially designed for outdoor winter athletes, might protect against bronchoconstriction triggered by inhalation of cold and dry air.

CONCLUSION

EIA in elite athletes should be managed as in any individual with asthma, but the risk of developing tolerance to bronchodilators as well as doping aspects should always be taken into account.

Screening for exercise-induced bronchoconstriction in college athletes

OBJECTIVE

Previous studies have reported that the prevalence of exercise-induced bronchoconstriction (EIB) in athletes is higher than that of the general population. There is increasing evidence that athletes fail to recognize and report symptoms of EIB. As a result, there has been debate whether athletes should be screened for EIB, particularly in high-risk sports.

METHODS

We prospectively studied 144 athletes from six different varsity sports at a large National Collegiate Athletic Association Division I collegiate athletic program. Baseline demographics and medical history were obtained and the presence of asthma symptoms during exercise was documented. Each athlete subsequently underwent a eucapnic voluntary hyperventilation (EVH) test to document the presence of EIB. Exhaled nitric oxide (eNO) quantification was performed immediately before EVH testing. EIB was defined as a ≥10% decline in forced expiratory volume in 1 second compared with baseline.

RESULTS

Only 4 of 144 (2.7%) athletes were EIB-positive after EVH testing. The presence of symptoms was not predictive of EIB as only 2 of the 64 symptomatic athletes (3%) were EIB-positive based on EVH testing. Two of the four athletes who were found to be EIB-positive denied such symptoms. The mean baseline eNO in the four EIB-positive athletes was 13.25 parts per billion (ppb) and 24.5 ppb in the EIB-negative athletes.

CONCLUSIONS

Our data argue that screening for EIB is not recommended given the surprisingly low prevalence of EIB in the population we studied. In addition, the presence or absence of symptoms was not predictive of EIB and eNO testing was not effective in predicting EIB.

Effects of salbutamol on the contractile properties of human skeletal muscle before and after fatigue

AIM

The study examined the effects of an oral acute administration of the β2-agonist salbutamol (Sal) (6 mg) vs. placebo on muscle strength and fatigability in 12 non-asthmatic recreational male athletes in a randomized double-blind protocol.

METHODS

Contractile properties of the right quadriceps muscle were measured during electrical stimulations, i.e. twitch, 1-s pulse trains at 20 (P(20) ) and 80 Hz (P(80) ) and during maximal voluntary isometric contraction (MVIC) before (PRE) and after (POST) a fatigue-producing protocol set by an electromyostimulation (30 contractions, frequency: 75 Hz, on-off ratio: 6.25-20s). In addition, the level of muscle voluntary activation was measured.

RESULTS

In PRE and POST conditions, the peak torque (PT) of twitch, P(80) and MVIC were not modified by the treatment. The PT in POST P(20) was slightly, although not significantly, less affected by fatigue in Sal compared with placebo condition. Moreover, twitch half-relaxation time at PRE was smaller under Sal than under placebo (P < 0.05). No significant changes in the degree of voluntary activation were observed with Sal treatment in PRE or POST condition.

CONCLUSION

  Although these findings did not exclude completely an effect of Sal on peripheral factors of human skeletal muscle, oral acute administration of the β2-agonist Sal seems to be without any relevant ergogenic effect on muscle contractility and fatigability in non-asthmatic recreational male athletes.

Effect of vitamin supplementation on lung injury and running performance in a hot, humid, and ozone-polluted environment

In this study, the effect of vitamin C and E supplementation on lung injury and performance of runners were analyzed. Using a randomized, double-blinded, crossover design, nine runners participated in two experimental trials: a 2-week Vitamin trial (vitamin C = 500  mg/day + vitamin E = 100  IU/day) and a 2-week Placebo trial. At the end of each supplementation period the runners performed an 8-km time-trial run in a hot (31°C), humid (70% rh), and ozone-polluted (0.10  ppm O(3)) environmental chamber. Nasal lavage and blood samples were collected pre-, post-, and 6-h post-exercise to assess antioxidant status and CC16 as lung injury marker. Higher plasma (pre- and post-exercise) and nasal lavage (post-exercise) antioxidant concentration were found for the Vitamin trial. Nevertheless, this did not result in performance differences (Vitamin trial: 31:05  min; Placebo trial: 31:54  min; P = 0.075) even though significant positive correlations were found between antioxidant concentration and improvement in time to complete the run. CC16 was higher post-exercise in the Placebo trial (P < 0.01) in both plasma and nasal lavage. These findings suggest that antioxidant supplementation might help to decrease the lung injury response of runners when exercising in adverse conditions, but has little effect on performance.

Accuracy of eucapnic hyperpnea or mannitol to diagnose exercise-induced bronchoconstriction: a systematic review

BACKGROUND

Exercise challenge testing is the typical method for diagnosing exercise induced bronchoconstriction; however, alternate tests have been developed.

OBJECTIVE

The purpose of this paper was to summarize the current literature comparing eucapnic voluntary hyperpnea and mannitol with standard exercise challenge testing to determine whether either test is a suitable alternative to standard exercise testing for the diagnosis of exercise-induced bronchoconstriction.

METHODS

Using valid systematic review methods, a comprehensive search strategy to avoid publication bias, we identified 10 studies that compared exercise challenge testing with either eucapnic voluntary hyperpnea or mannitol.

RESULTS

For the 7 diagnostic cross-sectional studies that examined eucapnic voluntary hyperpnea, the sensitivity and specificity values were heterogeneous, ranging from 25 to 90% for sensitivity and 0 to 71% for specificity. In the 3 diagnostic cross-sectional studies that evaluated mannitol, the sensitivity and specificity ranged from 58 to 96% and 65 to 78%, respectively. For most studies, a representative spectrum of participants being tested was not used.

CONCLUSION

Given the heterogeneity in sensitivity and specificity of eucapnic voluntary hyperpnea studies and the relatively small number of studies that have examined mannitol, insufficient evidence is available to conclude that either of these tests are suitable alternatives to exercise challenge testing to detect exercise-induced bronchoconstriction. Additional research is required.

Exercise-Induced Lung Disease: Too Much of a Good Thing?

Exercise in children has important health benefits. However, in elite endurance athletes, there is an increased prevalence of exercise-induced bronchoconstriction and airway inflammation. Particularly at risk are those who practice in cold weather, ice rinks, swimming pools, and air pollution. The inflammation is caused by repetitive episodes of hyperventilation of cold, dry air, allergens, or toxins such as chlorine or air pollution. Children may be particularly at risk for lung injury under these conditions because of the immaturity and ongoing development of their lung. However, studies in pediatric athletes and exercising young children are sparse. Epithelial injury associated with hyperventilation of cold, dry air has not been described in children. However, exercise in the presence of air pollution and chlorine is associated with airway injury and the development of asthma in children; the effect appears to be modulated by both atopy and genetic polymorphisms. While management of exercise-induced bronchoconstriction and asthma is well established, there is little data to guide treatment or prevention of remodeling in athletes or inhalational lung injury in children. Studies underscore the need to maintain high levels of air quality. More investigations should be undertaken to better define the natural history, pathophysiology, and treatment of exercise-induced pulmonary inflammation in both elite athletes and exercising children.

Prevalence rate of exercise-induced bronchoconstriction in Annaba (Algeria) schoolchildren

BACKGROUND

We studied the prevalence rate of exercise-induced bronchoconstriction (EIB) in Annaba schoolchildren. No previous assessment of this syndrome had ever been done in Algeria.

METHODS

EIB was evaluated using the 6 min free running test (6MFRT) on 286 children, 87.4% of whom were 10-12 years old. They performed the test in the morning, during the autumn-winter season. Peak expiratory flow rate (PEFR) was measured before, and then 5 and 10 min after the 6MFRT, a 15% or more decrease in post-exercise PEFR being defined as significant.

RESULTS

EIB was much more frequent in asthmatic than in nonasthmatic children (47.0% vs. 13.9%, p < .001) and the drop in PEFR was more marked among the former. EIB was observed more often in a cool temperature (<8°C). There were relatively more children who were either eutrophic or overweight among those presenting an EIB. Past histories of nocturnal wheezing and rhinoconjunctivitis presented respectively the best specificity (96.7%) and sensitivity (84.8%). Children of unemployed workers presented the highest occurrence of EIB. Passive smoking appeared as the only factor being related to EIB among the indoor pollutants. The prevalence rate of asthma (6.7%) was higher than in a previous cross-sectional epidemiological survey study performed in the Maghreb. The prevalence rate of EIB (13.9%) was situated in the upper range of the results given worldwide.

CONCLUSIONS

These features of a fairly high bronchial hyperresponsiveness could be facilitated by the polluted environment of the city.

β₂-Agonists and physical performance: a systematic review and meta-analysis of randomized controlled trials

Inhaled β₂-agonists are commonly used as bronchodilators in the treatment of asthma. Their use in athletes, however, is restricted by anti-doping regulations. Controversies remain as to whether healthy elite athletes who use bronchodilators may gain a competitive advantage. The aim of this systematic review and meta-analysis is to assess the effects of inhaled and systemic β₂-agonists on physical performance in healthy, non-asthmatic subjects. To this end, MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched up to August 2009. Reference lists were searched for additional relevant studies. The search criteria were for randomized controlled trials examining the effect of inhaled or systemic β₂-agonists on physical performance in healthy, non-asthmatic subjects. Two authors independently performed the selection of studies, data extraction and risk of bias assessment. Parallel-group and crossover trials were analysed separately. Mean difference (MD) and 95% confidence intervals were calculated for continuous data and, where possible, data were pooled using a fixed effects model. Twenty-six studies involving 403 participants (age range 7-30 years) compared inhaled β₂-agonists with placebo. No significant effect could be detected for inhaled β₂-agonists on maximal oxygen consumption (VO₂(max)) [MD -0.14 mL · kg⁻¹ · min⁻¹; 95% CI -1.07, 0.78; 16 studies], endurance time to exhaustion at 105-110% VO₂(max) (MD -1.5 s; 95% CI -15.6, 12.6; four studies), 20-km time trial duration (MD -4.4 s; 95% CI -23.5, 14.7; two studies), peak power (MD -0.14 W · kg⁻¹; 95% CI -0.54, 0.27; four studies) and total work during a 30-second Wingate test (MD 0.80 J · kg⁻¹; 95% CI -2.44, 4.05; five studies). Thirteen studies involving 172 participants (age range 7-22 years) compared systemic β₂-agonists with placebo, with 12 studies involving oral and one study involving intravenous salbutamol. A significant effect was detected for systemic β₂-agonists on endurance time to exhaustion at 80-85% VO₂(max) (MD 402 s; 95% CI 34, 770; two studies), but not for VO₂(max) (placebo 42.5 ± 1.7 mL · kg⁻¹ · min⁻¹, salbutamol 42.1 ± 2.9 mL · kg⁻¹ · min⁻¹, one study), endurance time to exhaustion at 70% VO₂(max) (MD 400 s; 95% CI -408, 1208; one study) or power output at 90% VO₂(max) (placebo 234.9 ± 16 W, salbutamol 235.5 ± 18.1 W, one study). A significant effect was shown for systemic β₂-agonists on peak power (MD 0.91 W · kg⁻¹; 95% CI 0.25, 1.57; four studies), but not on total work (MD 7.8 J · kg⁻¹; 95% CI -3.3, 18.9; four studies) during a 30-second Wingate test. There were no randomized controlled trials assessing the effects of systemic formoterol, salmeterol or terbutaline on physical performance. In conclusion, no significant effects were detected for inhaled β₂-agonists on endurance, strength or sprint performance in healthy athletes. There is some evidence indicating that systemic β₂-agonists may have a positive effect on physical performance in healthy subjects, but the evidence base is weak.

Bronchial provocation tests in clinical practice

Bronchial hyperresponsiveness, which consists of an exaggerated response of the airways to bronchoconstrictor stimuli, is one of the main characteristics of asthma, presented in nearly all asthmatic patients. Bronchial hyperresponsiveness may also be present in other diseases, such as allergic rhinitis, chronic obstructive pulmonary disease, cystic fibrosis, heart failure and respiratory infection, and with some medications, such as β-blockers. Bronchial provocation tests (also known as bronchial challenges) are used to evaluate bronchial responsiveness. These tests have become increasingly used over the last 20 years, with the development and validation of accurate, safe and reproducible tests, and with the publication of well-detailed protocols. Several stimuli can be used in a bronchial challenge, and they are classified as direct and indirect stimuli. There are many indications for a bronchial challenge. In this review, we discuss the main differences between direct and indirect stimuli, and the use of bronchial challenges in clinical practice, especially for confirming diagnoses of asthma, exercise-induced bronchoconstriction and cough-variant asthma, and for use among elite-level athletes.

The inflammatory basis of exercise-induced bronchoconstriction

Exercise-induced bronchoconstriction (EIB) is common in individuals with asthma, and may be observed even in the absence of a clinical diagnosis of asthma. Exercise-induced bronchoconstriction can be diagnosed via standardized exercise protocols, and anti-inflammatory therapy with inhaled corticosteroids (ICS) is often warranted. Exercise-related symptoms are commonly reported in primary care; however, access to standardized exercise protocols to assess EIB are often restricted because of the need for specialized equipment, as well as time constraints. Symptoms and lung function remain the most accessible indicators of EIB, yet these are poor predictors of its presence and severity. Evidence suggests that exercise causes the airways to narrow as a result of the osmotic and thermal consequences of respiratory water loss. The increase in airway osmolarity leads to the release of bronchoconstricting mediators (eg, histamine, prostaglandins, leukotrienes) from inflammatory cells (eg, mast cells and eosinophils). The objective assessment of EIB suggests the presence of airway inflammation, which is sensitive to ICS in association with a responsive airway smooth muscle. Surrogate tests for EIB, such as eucapnic voluntary hyperpnea or the osmotic challenge tests, cause airway narrowing via a similar mechanism, and a response indicates likely benefit from ICS therapy. The complete inhibition of EIB with ICS therapy in individuals with asthma may be a useful marker of control of airway pathology. Furthermore, inhibition of EIB provides additional, useful information regarding the identification of clinical control based on symptoms and lung function. This article explores the inflammatory basis of EIB in asthma as well as the effect of ICS on the pathophysiology of EIB.

Current concepts in the diagnosis and management of exercise-induced bronchospasm

Exercise-induced bronchospasm (EIB) is a common occurrence in individuals with asthma, though it can also affect individuals without asthma. It occurs frequently in athletes. Common symptoms include coughing, dyspnea, chest tightness, and wheezing; however, there can be a variety of more subtle symptoms. The differential diagnosis of EIB is broad and includes several pulmonary and cardiac disorders. During the initial evaluation, a complete history, physical examination, and spirometry should be performed. In most patients with EIB, the baseline spirometry is normal; therefore, bronchoprovocation testing is strongly recommended. Both pharmacologic and nonpharmacologic approaches are important in the treatment of EIB. Management of EIB on the sideline of athletic events requires preparation and immediate access to rescue inhalers.

Asthma in swimmers: a review of the current literature

Asthma is common in many types of athletes, but its prevalence appears to be particularly high in swimmers. Long-term and acute exposure to swimming pool disinfectants has been shown to increase asthma risk in swimmers through inducing oxidative stress, which results in inflammation of the pulmonary epithelium and subsequent airway remodeling. Individuals with specific genotypes are more likely to develop asthma when exposed to inhaled irritants. Therefore, it is important for physicians to be knowledgeable about the risks associated with asthma in swimmers, as well as the diagnostic techniques and practices to reduce asthma symptoms.