Provocation by eucapnic voluntary hyperpnoea to identify exercise induced bronchoconstriction

Reduced airway responsiveness in nonelite runners

PURPOSE

The effects of endurance training on airway responsiveness in nonasthmatic subjects are poorly defined. We hypothesized that airway responsiveness may differ between none-lite endurance athletes and sedentary subjects, and studied healthy, nonelite runners and sedentary controls by single-dose methacholine challenges carried out in the absence of deep inspirations, in that deep inspirations are known to oppose airway narrowing in nonasthmatic subjects.

METHODS

A total of 20 nonasthmatic none-lite runners (mean age+/- SD: 43.0+/- 8.5 yr; training volume: 68 km.wk; range: 40-100; racing experience: 11+/- 8 yr) and 20 sedentary controls (age: 44.0+/- 20.6 yr) were studied, all of them being normo-reactive to standard methacholine challenge up to 25 mg.mL concentration. All subjects were studied at rest; six runners were also studied about 1 h after completing the Palermo marathon (December 8, 2001). The primary outcome of the study was the inspiratory vital capacity (IVC) obtained after single-dose methacholine inhalation at the end of 20 min of deep inspiration prohibition.

RESULTS

At rest, IVC decreased by 10.5+/-8.1% after challenge with methacholine at 75 mg.mL in athletes, and by 24.3+/-16.1% after a methacholine concentration of 52+/-5.7 mg.mL in sedentary controls (P=0.002). The decreased response to methacholine in runners did not correlate with static lung volumes, amount of weekly training, or running experience.

CONCLUSION

Methacholine challenge under deep inspiration prohibition revealed that endurance training attenuates airway responsiveness in nonasthmatic, none-lite runners. Airway hyporesponsiveness was potentiated after the marathon, suggesting involvement of humoral (i.e., catecholamine levels), airway factors (i.e., nitric oxide), or both in modulating airway tone after exercise.

Effects of cysteine donor supplementation on exercise-induced bronchoconstriction

PURPOSE

Reactive oxygen/nitrogen species (ROS/RNS) in resident airway cells may be important in bronchoconstriction following exercise. Glutathione (GSH) is a major lung antioxidant and could influence pathological outcomes in individuals with exercise-induced bronchoconstriction (EIB). This study examined the effects of supplementation with undenatured whey protein (UWP) in subjects exhibiting airway narrowing following eucapnic voluntary hyperventilation (EVH), a surrogate challenge for diagnosis of EIB. UWP is a cysteine donor that augments GSH production.

METHODS

In a randomized, double-blind, placebo-controlled study, 18 EIB-positive subjects (age: 25.2 +/- 9.01 yr; weight: 77.3 +/- 18.92 kg; height: 1.7 +/- 0.09 m) with post-EVH falls of > or =10% in FEV1 received 30 g UWP (TX) or casein placebo (PL)/d. Subjects performed 6-min EVH challenges before and after 4 and 8 wk of supplementation. Exhaled nitric oxide (eNO) was measured serially before spirometry and at 1-wk intervals. Spirometry was performed pre- and 5, 10, and 15 min postchallenge.

RESULTS

Subjects exhibited significant mean improvement in postchallenge falls in FEV(1) from 0 wk (-22.6 +/- 12.22%) with TX at 4 (-18.9 +/- 12.89%, P < 0.05) and 8 wk (-16.98 +/- 11.61%, P < 0.05) and significant mean reduction in post-EVH peak falls in FEF(25-75) from 0 wk (-40.6 +/- 15.28%) with TX at 4 (-33.1 +/- 17.11%, P < 0.01) and 8 (-29.7 +/- 17.42%, P < 0.05) wk. No changes in FEV(1) or FEF(25-75) were observed in the PL group at any time point. Mean eNO for PL and TX groups at 0, 4, and 8 wk (46.8 +/- 31.33, 46.5 +/- 35.73, 49.3 +/- 37.12 vs 35.2 +/- 26.87, 29.1 +/- 17.26, 34.7 +/- 21.11 ppb, respectively) was not significantly different.

CONCLUSIONS

UWP may augment pulmonary antioxidant capacity and be therapeutically beneficial in individuals exhibiting EIB, as postchallenge pulmonary function improved with supplementation. The lack of significant change in eNO suggests that the pulmonary function improvements from UWP supplementation are independent of eNO.

Making the diagnosis of asthma in the athlete

This article encompasses a discussion of the clinical presentation and features as various diagnostic modalites of bronchoprovocation and differential diagnosis used in screening for asthma in the athlete. A comparative analysis of these modalities, including questionnaire, treadmill, eucapneic hyperventilation, as well as field challenge, is provided with sensitivities and specificities, predictive value, and application to clinical practice. The indication and mechanics of each diagnostic modality is discussed, providing the clinician with a comprehensive understanding of the principles and procedures used to diagnosis asthma in the athlete.

Mid-expiratory flow versus FEV1 measurements in the diagnosis of exercise induced asthma in elite athletes

BACKGROUND

A fall in FEV(1) of > or =10% following bronchoprovocation (eucapnic voluntary hyperventilation (EVH) or exercise) is regarded as the gold standard criterion for diagnosing exercise induced asthma (EIA) in athletes. Previous studies have suggested that mid-expiratory flow (FEF(50)) might be used to supplement FEV(1) to improve the sensitivity and specificity of the diagnosis. A study was undertaken to investigate the response of FEF(50) following EVH or exercise challenges in elite athletes as an adjunct to FEV(1).

METHODS

Sixty six male (36 asthmatic, 30 non-asthmatic) and 50 female (24 asthmatic, 26 non-asthmatic) elite athletes volunteered for the study. Maximal voluntary flow-volume loops were measured before and 3, 5, 10, and 15 minutes after stopping EVH or exercise. A fall in FEV(1) of > or =10% and a fall in FEF(50) of > or =26% were used as the cut off criteria for identification of EIA.

RESULTS

There was a strong correlation between DeltaFEV(1) and DeltaFEF(50) following bronchoprovocation (r = 0.94, p = 0.000). Sixty athletes had a fall in FEV(1) of > or =10% leading to the diagnosis of EIA. Using the FEF(50) criterion alone led to 21 (35%) of these asthmatic athletes receiving a false negative diagnosis. The lowest fall in FEF(50) in an athlete with a > or =10% fall in FEV(1) was 14.3%. Reducing the FEF(50) criteria to > or =14% led to 13 athletes receiving a false positive diagnosis. Only one athlete had a fall in FEF(50) of > or =26% in the absence of a fall in FEV(1) of > or =10% (DeltaFEV(1) = 8.9%).

CONCLUSION

The inclusion of FEF(50) in the diagnosis of EIA in elite athletes reduces the sensitivity and does not enhance the sensitivity or specificity of the diagnosis. The use of FEF(50) alone is insufficiently sensitive to diagnose EIA reliably in elite athletes.

Clinical Role of Rapid-Incremental Tests in the Evaluation of Exercise-Induced Bronchoconstriction

STUDY OBJECTIVE

To determine whether rapid-incremental work rate (IWR) testing would be as useful as standard high-intensity constant work rate (CWR) protocols in eliciting exercise-induced bronchoconstriction (EIB) in susceptible subjects.

DESIGN AND SETTING

A cross-sectional study performed in a clinical laboratory of a tertiary, university-based center.

SUBJECTS AND MEASUREMENTS

Fifty-eight subjects (32 males, age range, 9 to 45 years) with suspected EIB were submitted to CWR testing (American Thoracic Society/European Respiratory Society guidelines) and IWR testing on different days; 21 subjects repeated both tests within 4 weeks. Spirometric measurements were obtained 5, 10, 15, and 20 min after exercise; a FEV1 decline > 10% defined EIB.

RESULTS

Twenty-seven subjects presented with EIB either after CWR or IWR testing; 21 subjects had EIB in response to both protocols (kappa = 0.78, excellent agreement; p < 0.001). Of the six subjects in whom discordant results were found, two had EIB only after IWR. Assuming CWR as the criterion test, IWR combined high positive and negative predictive values for EIB detection (91.3% and 88.6%, respectively). Tests reproducibility in eliciting EIB were similar (kappa = 0.80 and 0.72 for CWR and IWR, respectively; p < 0.001). Total and intense (minute ventilation > 40% of maximum voluntary ventilation) ventilatory stresses did not differ between EIB-positive and EIB-negative subjects, independent of the test format. There were no significant between-test differences on FEV(1) decline in EIB-positive subjects (25.7 +/- 10.8% vs 23.7 +/- 10.0%, respectively; p > 0.05). Therefore, no correlation was found between exercise ventilatory response and the magnitude of EIB after either test (p > 0.05).

CONCLUSIONS

Rapid-incremental protocols (8 to 12 min in duration) can be as useful as high-intensity CWR tests in diagnosing EIB in susceptible subjects. Postexercise spirometry should be performed after incremental cardiopulmonary exercise testing when EIB is clinically suspected.

Airway Narrowing Measured by Spirometry and Impulse Oscillometry Following Room Temperature and Cold Temperature Exercise

STUDY OBJECTIVE

The efficacy of using impulse oscillometry (IOS) as an indirect measure of airflow obstruction compared to spirometry after exercise challenges in the evaluation of exercise-induced bronchoconstriction (EIB) has not been fully appreciated. The objective was to compare airway responses following room temperature and cold temperature exercise challenges, and to compare whether IOS variables relate to spirometry variables.

DESIGN

Spirometry and IOS were performed at baseline and for 20 min after challenge at 5-min intervals.

SETTING

Two 6-min exercise challenges, inhaling either room temperature (22.0 degrees C) or cold temperature (- 1 degrees C) dry medical-grade bottled air. At least 48 h was observed between these randomly assigned challenges.

PARTICIPANTS

Twenty-two physically active individuals (12 women and 10 men) with probable EIB.

INTERVENTIONS

Subjects performed 6 min of stationary cycle ergometry while breathing either cold or room temperature medical-grade dry bottled air. Subjects were instructed to exercise at the highest intensity sustainable for the duration of the challenge. Heart rate and kilojoules of work performed were documented to verify exercise intensity.

MEASUREMENTS AND RESULTS

Strong correlations were observed within testing modalities for post-room temperature and post-cold temperature exercise spirometry and IOS values. Spirometry revealed no differences in postexercise peak falls in lung function between conditions; however, IOS identified significant differences in respiratory resistance (p < 0.05), with room temperature-inspired air being more potent than cold temperature-inspired air.

CONCLUSIONS

Correlations were found between spirometric and IOS measures of change in airway function for both exercise challenges, indicating close equivalency of the methods. The challenges appeared to elicit the EIB response by a similar mechanism of water loss, and cold temperature did not have an additive effect. IOS detected a difference in degree of response between the temperatures, whereas spirometry indicated no difference, suggesting that IOS is a more sensitive measure of change in airway function.

Impact of changes in the IOC-MC asthma criteria: a British perspective

BACKGROUND

Since 2001 the International Olympic Committee-Medical Commission (IOC-MC) has required athletes using inhaled beta2 agonists to provide clinical evidence of their asthmatic condition. The aim of this study was to compare the reported prevalence of asthma at the 2000 and 2004 Olympic Games in the Great British Olympic team (Team GB).

METHODS

Following local ethics committee approval, 271 athletes (165 men) from the 2004 Team GB volunteered and provided written informed consent. An athlete was confirmed asthmatic if he or she had a positive bronchoprovocation or bronchodilator test as defined by the IOC-MC. Pre-Olympic medical forms from the 2000 Team GB were also examined to establish the prevalence of asthma among the members of Team GB at the 2000 Olympic Games.

RESULTS

The prevalence of asthma in the two teams at the 2000 and 2004 Olympic Games was similar (21.2% and 20.7%, respectively). In the 2004 Olympic Games 13 of 62 athletes (21.0%) with a previous diagnosis of asthma tested negative. A further seven with no previous diagnosis of asthma tested positive.

CONCLUSIONS

The prevalence of asthma within Team GB remained unchanged between 2000 and 2004. The IOC-MC requirement that asthmatic athletes must submit documented evidence of asthma has highlighted that 13 (21.0%) previously diagnosed as asthmatic failed to demonstrate evidence of asthma while seven athletes with no previous history or diagnosis of asthma tested positive. Screening for asthma within elite athletic populations using bronchoprovocation challenges appears warranted to assist athletes in preparing more effectively for major sporting events.

Cold air inhalation does not affect the severity of EIB after exercise or eucapnic voluntary hyperventilation

INTRODUCTION

Exercise-induced bronchoconstriction (EIB) is thought to result from osmotic and thermal events of air conditioning during exercise at high ventilation rates. The purpose of this study was to evaluate lung function after exercise and eucapnic voluntary hyperventilation (EVH) while breathing both room-temperature and cold-temperature dry bottled air.

METHODS

Twenty-two subjects were identified as EIB probable by a fall of >or=7% in forced expiratory volume in the first second of exhalation (FEV1) using a 6-min room-temperature EVH challenge (RTEVH; 22.0 degrees C). Subjects then randomly performed three 6-min challenges: cold-temperature EVH (CTEVH; -1 degrees C), room-temperature exercise (RTEX; 22.0 degrees C), and cold-temperature exercise (CTEX; -1 degrees C), with a period of at least 48 h observed between challenges. Spirometry was performed at baseline and at 5, 10, 15, and 20 min postchallenge.

RESULTS

Reasonable agreement was found between challenge modes and room-temperature and cold-temperature challenges. Postchallenge percent falls in FEV1 were -15.21, -13.80, -13.12, and -10.69 for RTEVH, CTEVH, RTEX, and CTEX, respectively. RTEVH resulted in a significantly greater percent fall in FEV1 than CTEX (P=0.048); no other differences in FEV1 were observed.

CONCLUSION

Similar postchallenge percent falls in FEV1 for room- and cold-temperature EVH and exercise suggest that dryness is essential to test conditions, as cold temperature did not have an additive effect to the EIB response.

Effects of montelukast on airway narrowing from eucapnic voluntary hyperventilation and cold air exercise

BACKGROUND

Exercise induced bronchoconstriction (EIB) is common in elite athletes. Eucapnic voluntary hyperventilation (EVH) is a laboratory test recommended for the identification of EIB in athletes, secondary to a field exercise challenge. Montelukast attenuates EIB, but its protective effect against airway narrowing from EVH has not been investigated.

OBJECTIVE

To examine the effectiveness of montelukast after exercise and after EVH.

METHODS

A randomised, placebo controlled, double blind, crossover study was performed with 11 physically active EIB positive subjects (eight men, three women; mean (SD) age 22.8 (6.8) years). Six hours before each of the following challenges 10 mg montelukast or placebo was ingested: (a) a six minute, cold air (-3 degrees C) maximal effort work accumulation cycle ergometer exercise; (b) EVH, breathing 5% CO(2) compressed air at 85% maximal voluntary ventilation for six minutes. Spirometry was performed before and 5, 10, and 15 minutes after the challenge. At least 48 hours was observed between challenges.

RESULTS

No differences in forced expiratory volume in one second (FEV(1)) were found after the two challenges. Exercise and EVH resulted in falls in FEV(1) of 22.4 (18.0) and 25.6 (16.8) respectively. Falls in FEV(1) after montelukast were less than after placebo (10.6 (10.6) and 14.3 (11.3) after exercise and EVH respectively; p<0.05). Montelukast provided protection against bronchoconstriction (59% and 53%; p<0.05) for eight exercising subjects and 10 EVH subjects; no protection was afforded for three exercising and one EVH challenged subject.

CONCLUSIONS

Both exercise and EVH were potent stimuli of airway narrowing. A single dose of montelukast provided reasonable protection in attenuating bronchoconstriction from either exercise or EVH. The similar protection by montelukast suggests that EVH is a suitable laboratory surrogate for EIB evaluation.

Single-dose agents in the prevention of exercise-induced asthma: a descriptive review

Exercise-induced asthma (EIA) refers to the transient narrowing of the airways that occurs after vigorous exercise in 50-60% of patients with asthma. The need to condition the air inspired during exercise causes water to be lost from the airway surface, and this is thought to cause the release of inflammatory mediators (histamine, leukotrienes, and prostaglandins) from mast cells. EIA is associated with airway inflammation and its severity is markedly reduced following treatment with inhaled corticosteroids. Drugs that inhibit the release of mediators and drugs that inhibit their contractile effects are the most successful in inhibiting EIA. Single doses of short-acting beta(2)-adrenoceptor agonists, given as aerosols immediately before exercise, are very effective in the majority of patients with asthma, providing about 80% protection for up to 2 hours. Long-acting beta(2)-adrenoceptor agonists (LABAs) given in single doses can be effective for up to 12 hours when used intermittently, but tolerance to the protective effect occurs if they are taken daily. Drugs such as cromolyn sodium (sodium cromoglicate) and nedocromil given as aerosols are less effective than beta(2)-adrenoceptor agonists (beta(2)-agonists), providing 50-60% protection for only 1-2 hours, but they have some advantages. They do not induce tolerance, the aerosol dosage can be easily titrated for the individual, and the protective effect is immediate. Because they cause no significant adverse effects, multiple doses can be used in a day. Leukotriene receptor antagonists, such as montelukast and zafirlukast, are also used for the prevention of EIA and provide 50-60% protection for up to 24 hours when given as tablets. Tolerance to the protective effect does not develop with regular use. If breakthrough EIA occurs, a beta(2)-agonist can be used effectively for rescue medication. For those patients with more persistent symptoms, the use of a LABA in combination with an inhaled corticosteroid has raised a number of issues with respect to the choice of prophylactic treatment for EIA. The most important issue is the development of tolerance to the protective effect of a LABA such that extra treatment may be needed in the middle of a treatment period. Recommending extra doses of a beta(2)-agonist to control EIA is not advisable on the basis that multiple doses can enhance the severity of EIA, delay spontaneous recovery from bronchoconstriction, and enhance responses to other contractile stimuli. It is time to take into account the advantages and disadvantages of the different drugs available to prevent EIA and to recognize that there are some myths related to their use in EIA.

Bronchoconstriction provoked by exercise in a high-particulate-matter environment is attenuated by montelukast

Airborne ultrafine and fine particulate matter (PM1 from fossil-fueled internal combustion engines may cause abnormal airway narrowing. Because of high PM1 exposure from ice resurfacing machines, the ice-rink athlete is especially vulnerable to PM1 toxicity. The purpose of this study was to evaluate protection by a single dose of montelukast in college ice hockey players following PM1 exposure exercise. Nine male ice hockey players (age 19.3+/-1.22 yr) performed 4 randomized, double-blinded, high-intensity, 6-min cycle ergometer trials in low [PM1] (2260+/-500 particles/cm3) and high [PM1] (348,600+/-121,600 particles/cm3) after placebo or montelukast. Pre- and postspirometry showed similar peak FEV1 (forced expiratory volume in 1 s) falls between placebo and montelukast after low [PM1] trials (14.5+/-18.06 vs. 9.5+/-11.75% of baseline, respectively). Peak FEV1 falls after high [PM1] trials were greater for placebo than for montelukast (17.3+/-9.79% vs. 1.7+/-5.77% of baseline; p<.0001). High [PM1] FEV1 fall after exercise following montelukast ingestion was less than after exercise following placebo ingestion under high and low [PM1] conditions and after exercise following montelukast ingestion under low [PM1] conditions at 5, 10, and 15 min postchallenge (p<.004, .0006, .009, respectively). Montelukast provided greater protection against bronchoconstriction after exercise during high [PM1] than low [PM1] exposure (approximately 90% vs. approximately 35%), suggesting that bronchoconstriction from PM1 exposure is predominately leukotriene mediated. The precise mechanism of airborne PM1-induced leukotriene-mediated airway narrowing remains unclear.

Asthma associated with exercise

Exercise is a potent stimulus to asthma. The diagnosis is not always straightforward, and health care providers should have a high index of suspicion. Treatment usually controls exercise-induced asthma but usually requires therapy tailored for each individual patient.

An evaluation of standardizing target ventilation for eucapnic voluntary hyperventilation using FEV1

Athletes are required to provide objective documentation of exercise-induced bronchoconstriction (EIB) to use beta2-agonists during Olympic competition. A positive response to bronchial provocation by eucapnic voluntary hyperventilation (EVH) is considered acceptable confirmation of EIB. Thirty times forced expiratory volume in the first second (FEV1) is recommended as EVH target ventilation (TV), an intensity intended to estimate 85% of maximal voluntary ventilation (MVV). There is a paucity of data examining the accuracy of predicting MVV from FEV1 in elite athletes. The purpose of this study was to evaluate the efficacy of 30 x FEV1 as standardized EVH TV. Maximal minute ventilation during exercise (VEmax) and pulmonary function of 78 elite winter athletes (25 males, 53 females; 25 EIB positive, 53 normal) were analyzed retrospectively. Adequacy and variability of the equation was ascertained by examining the ratio of EVH TV (30 x FEV1) to VEmax. VEmax was 99+/-11% of predicted MVV (35 x FEV1) and was positively related (r=0.85, p < or = 0.05). TV was 88+/-9% of VEmax (range: 64-109). For elite athletes, the high variability in 30 x FEV1 to standardize TV for EVH may result in under-diagnosis for low-end outliers. Since VEmax of elite endurance athletes is typically known (via maximal aerobic testing) we recommend 85% VEmax as a more accurate and reliable method to establish EVH TV for this group; if VEmax is not available, then 85% of measured MVV may be used.

Airways hyperresponsiveness in high school athletes

Adult athletes have a higher prevalence (11%-50%) of exercise-induced bronchoconstriction (EIB) and airways hyperresponsiveness (AHR) than the population at large (7%-11%): reports describing EIB/AHR in adolescent athletes are scant.

HYPOTHESES

1) a minimum AHR prevalence of 20% would be revealed in a group of high school athletes; 2) demographic data would predict AHR; 3) AHR-positive athletes would preferentially choose low ventilation sports. Eucapnic voluntary hyperpnea (EVH) was used to test for AHR in 23% of all athletes (79 of 343) of a midwestern high school. The AHR was defined by at least a 10%, 20%, or 25% decline in FEV1, FEF25-75, or PEFR at 1, 5, 10, or 15-min post-EVH, respectively.

RESULTS

30 of 79 (38%) tested positive for AHR; demographic data tended to predict AHR, as correlations between the total number of years exercised with the greatest decline in FEV1 and the total number of days exercised with the greatest decline in FEV1 following the EVH challenge tended to be significant (r = 0.354; p = 0.055 and r=0.314; p = 0.091, respectively); and 69% of AHR-positive students played only low ventilation sports.

CONCLUSION

AHR prevalence was 38% in athletes of a midwestern high school; demographic data tended to predict AHR; those with AHR preferentially play low ventilation sports.

Cardio-respiratory measures following isocapnic voluntary hyperventilation

In some individuals, breathing is greater than at rest following voluntary hyperventilation. Most previous investigations have employed short hyperventilation periods; here we examine the time course of cardio-respiratory measures before, during, and after a 5-min voluntary hyperventilation, maintaining isocapnia throughout. We examined the possible co-involvement of the cardiovascular system; hypothesising that post-hyperventilation hyperpnoea results from an increase in autonomic arousal. In four subjects (two males, two females) of 18 (nine males, nine females) we observed a post-hyperventilation hyperpnoea, characterised by a slow decline of ventilation toward resting levels with a time constant of 109.0 +/- 16.1s. By contrast, heart rate, and systolic and diastolic blood pressure were unchanged from rest during and after voluntary hyperventilation for all subjects. We concluded that males and females were equally likely to exhibit post-hyperventilation hyperpnoea, and suggest that they may be characterised by an increased resting heart rate and the choice of breathing frequency to increase ventilation during the voluntary hyperventilation. We further concluded that post-hyperventilation hyperpnoea is rare, but when present is a strong and lasting phenomenon, and that it is not the result of an increased autonomic arousal.

Field exercise vs laboratory eucapnic voluntary hyperventilation to identify airway hyperresponsiveness in elite cold weather athletes

STUDY OBJECTIVE

For the 2002 Winter Olympic Games, athletes were required to submit objective evidence of asthma or exercise-induced bronchoconstriction (EIB) for approval to inhale a beta(2)-agonist. Eucapnic voluntary hyperventilation (EVH) was recommended as a laboratory challenge that would identify airway hyperresponsiveness (AHR) consistent with EIB. The objective was to compare the change in FEV(1) provoked by EVH with that provoked by exercise in cold weather athletes.

DESIGN

Spirometry was measured before and for 15 min after challenges. The two challenges were performed in random order at least 24 h apart.

SETTING

EVH was performed in the laboratory at 19 degrees C, and exercise took place in the field in the cold (2 degrees C, 45% relative humidity).

PARTICIPANTS

Thirty-eight athletes (25 female subjects; median age, 16 years).

INTERVENTIONS

For the EVH, athletes inhaled dry air containing 5% carbon dioxide for 6 min at a target ventilation equivalent to 30 times baseline FEV(1). Exercise was performed by cross-country skiing, ice skating, or running for 6 to 8 min.

MEASUREMENTS AND RESULTS

AHR consistent with EIB was defined as >or= 10% fall in FEV(1) from baseline after challenge. Eleven athletes were exercise positive (EX+) [FEV(1) fall, 20.5 +/- 7.3%], and 17 athletes were EVH positive (FEV(1) fall, 14.5 +/- 4.5%) [mean +/- SD]. Of 19 subjects with AHR, 58% were identified by exercise and 89% were identified by EVH. EVH identified 9 of 11 subjects who were EX+ and a further 8 subjects with potential for EIB. The average ventilation during EVH was 28 times FEV(1).

CONCLUSION

Performing EVH for 6 min in the laboratory had a greater chance of identifying AHR in these athletes compared with 6 to 8 min of field exercise in the cold. The EVH test will be useful to evaluate elite summer sports athletes whose widely different forms of exercise provide an "equipment" challenge to any laboratory.

Review of exercise-induced asthma

PURPOSE

The purpose of this manuscript is to review the recent literature on exercise-induced asthma (EIA) and summarize the pathogenesis, diagnosis, and treatment of this condition.

METHOD

A review of the English language medical literature was performed to obtain articles on EIA.

RESULTS

The pathophysiology of EIA is not fully understood, but there are two theories: 1) the hyperosmolar theory and 2) the airway rewarming theory. In addition, there have been data to show that airway inflammation is present in some elite athletes, especially in cold weather sports. The diagnosis of EIA is usually straightforward in most patients, but a number of patients may have atypical symptoms and may be more difficult to diagnose. They may well need exercise testing or eucapnic voluntary ventilation testing. Most people respond to treatment with an inhaled beta agonist and or cromolyn before exercise, but some patients will also need other medications, including daily medications such as inhaled steroids. When treatment does not control the problem, then further diagnostic evaluation should be done to rule out conditions other than EIA, such as vocal cord dysfunction or cardiac or pulmonary problems.

CONCLUSIONS

EIA is a condition that may occur in schoolchildren in gym class and also in Olympic athletes. The diagnosis and treatment is usually fairly straightforward, but at times it may be challenging. However, all patients should be followed to make sure that the correct diagnosis is made and to make sure that treatment is effective.

Activity-induced asthma

Exercise is the most common trigger of persistent childhood asthma. The history for EIA can be complicated by the lack of perception of significant airway obstruction during exercise. One must carefully identify those children with EIA from the group of children who report low level of activity because of lack of interest or because they are out of shape. Baseline spirometry of children with persistent asthma is frequently normal. Spirometry is important to identify those children with EIA who underrecognize their disease, but normal results should not be used as evidence of absence of disease. Formal exercise testing should be considered when the diagnosis is unclear or if there seems to be a lack of bronchoprotection with inhaled albuterol. The goal of treatment of EIA should be the attainment of a normal activity level for children and adolescents. Identification of the limits imposed by EIA and establishment of goals of therapy with the child and family should be the initial action. Inactivity or reduced exertion, in the presence of this diagnosis. should not be accepted. Therapy for EIA starts with control of the underlying persistent asthma. Inhaled corticosteroids are the most effective initial treatment of both EIA and persistent asthma in children and adolescents. Exercise-induced asthma is a common aspect of a prevalent disease that warrants proper diagnosis and treatment. With appropriate therapy, children with EIA should be able to participate in sports and maintain normal activity. They should strive to compete in the same playing field as their peers and have the same goals as those children and athletes who do not have exercise-induced asthma.

Mannitol as a challenge test to identify exercise-induced bronchoconstriction in elite athletes

Bronchial provocation tests provide objective criteria for asthma and exercise-induced bronchoconstriction (EIB) and were recommended to justify the use of inhaled beta2-agonists by athletes at the Winter Olympics 2002. Eucapnic voluntary hyperpnea (EVH) was one test recommended to identify EIB. Provocation with EVH requires a special dry gas mixture limiting its availability. Provocation tests with osmotic aerosols require less expensive equipment that is easily portable. We assessed the sensitivity of a challenge with mannitol to identify responsiveness to EVH in 50 elite summer sport athletes who were unselected if they had respiratory symptoms. Asthma was previously diagnosed by a doctor in 27 subjects, and 21 subjects were currently under treatment for EIB or asthma. The mean predicted FEV1 was 103.6 +/- 10.8%, FVC was 99 +/- 13.3%, and mean forced expiratory flow during the middle half of the FVC was 104 +/- 22.7%. A total of 25 subjects were positive to EVH challenge (mean percentage of fall in FEV1 was 25.4 +/- 15% SD), and 26 subjects had a positive mannitol challenge (geometric mean [95% confidence interval] provoking dose causing a 10% fall in forced expiratory volume in one second [PD10] was 202 mg [134, 300], with 24 of the subjects positive to both challenges). Mannitol had a sensitivity of 96% and specificity of 92% to identify a positive response to EVH and, as such, could be used as an alternative to EVH to identify EIB.

Methods for "indirect" challenge tests including exercise, eucapnic voluntary hyperpnea, and hypertonic aerosols

Bronchial provocation tests that use stimuli that act indirectly to cause airway narrowing have a high specificity for identifying people with active asthma who have the potential to respond to treatment with antiinflammatory drugs. The first test to be developed was exercise and it was used to assess the efficacy of drugs such as sodium cromoglycate. Eucapnic voluntary hyperpnea was developed later, as a surrogate test for exercise. Hypertonic aerosols were introduced to mimic the dehydrating effects of evaporative water loss that occurs during hyperpnea. A wet aerosol of 4.5% saline or a dry powder formulation of mannitol is used. At present the indirect challenge tests are becoming increasingly recognised as appropriate for monitoring treatment with inhaled steroids. Indirect tests identify those with potential for exercise-induced bronchoconstriction, an important problem for some occupations, such as the defence forces, fire fighters and the police force and for some athletic activities. The advantage in using an indirect challenges, over a direct challenge with a single pharmacological agonist, is that a positive response indicates that inflammatory cells and their mediators (prostaglandins, leukotrienes and histamine) are present in the airways in sufficient numbers and concentration to indicate that asthma is active at the time of testing. The corollary to this is that a negative test in a known asthmatic indicates good control or mild disease. Another advantage is that healthy subjects do not have significant airway narrowing to indirect challenge tests. The protocols used for challenge with indirectly acting stimuli are presented in detail.

Responses to bronchial challenge submitted for approval to use inhaled beta2-agonists before an event at the 2002 Winter Olympics

BACKGROUND

There has been an increase in the number and percentage of athletes competing in Olympic Games notifying use of beta2-agonists, from 1.7% at Los Angeles (1984) to 5.5% at Sydney (2000). For Salt Lake City (2002), the International Olympic Committee requested objective evidence to use beta2-agonists for asthma or exercise-induced asthma (EIA).

OBJECTIVE

The objective of this study was to evaluate the evidence submitted for approval to use a beta2-agonist.

METHODS

Objective evidence for asthma or EIA included (1) an increase of 12% or more of the predicted FEV1 in response to bronchodilator, (2) a reduction in FEV1 of 10% or greater from baseline in response to exercise or eucapnic voluntary hyperpnea, (3) a PD20 FEV1 to methacholine or histamine at a dose of less than 200 microg (2 mg/mL) or less than 1320 microg (13.2 mg/mL) for those taking inhaled corticosteroids for 3 months.

RESULTS

There were 165 applications. Of these, 147 (89%) included evidence of a challenge, bronchodilator response, or both, and 163 test results were submitted. One hundred thirty (5.2%) applications were approved. For those with positive responses, the median value (1) was 16.2% of predicted FEV1 for response to a bronchodilator (n = 13), (2) was a 15.9% decrease in FEV1 for response to a physical challenge (n = 36), and, (3) for PD20 FEV1, was 173 microg for response to a pharmacologic challenge (n = 45).

CONCLUSION

The analysis demonstrated that it is feasible to request objective evidence to justify use of beta2-agonists on the medical grounds of asthma or EIA.

Use of aerosols for bronchial provocation testing in the laboratory: where we have been and where we are going

Bronchial provocation testing with pharmacological agents that act directly on airway smooth muscle has important limitations. These include the inability to identify exercise-induced asthma (EIA), to differentiate the airway hyperresponsiveness (AHR) of airway remodelling from the AHR of active inflammation and to differentiate between doses of steroids. Recent studies show that tests that act indirectly to narrow airways are more sensitive than pharmacological agents for identifying airway inflammation and response to treatment. Adenosine monophosphate (AMP) is an indirect challenge that acts on mast cells to cause release of mediators. Hypertonic saline is another and, since its development in the 1980s, has become widely used in Australia. Hypertonic (4.5%) saline is used to identify those with active asthma, those with EIA and those who wish to enter certain occupations or sports (e.g., diving). The recent development, again in Australia, of a test that uses dry powder mannitol has promise for use in the laboratory, the office, or for testing in the field. AHR to mannitol identifies people with EIA and is an estimate of its severity. The mannitol response is modified by drugs used to prevent EIA, implying that similar mediators are involved. A mannitol test can be used to monitor response to steroids and is more sensitive than histamine for identifying persistent airway hyperresponsiveness in asthmatics well controlled on steroids. These findings suggest that indirect challenges give more useful clinical information about currently active asthma and the response to treatment than direct challenge and they will become more widely used.

Exercise-induced bronchospasm in the elite athlete

The term exercise-induced bronchospasm (EIB) describes the acute transient airway narrowing that occurs during and most often after exercise in 10 to 50% of elite athletes, depending upon the sport examined. Although multiple factors are unquestionably involved in the EIB response, airway drying caused by a high exercise-ventilation rate is primary in most cases. The severity of this reaction reflects the allergic predisposition of the athlete, the water content of the inspired air, the type and concentration of air pollutants inspired, and the intensity (or ventilation rate) of the exercise. The highest prevalence of EIB is seen in winter-sport populations, where athletes are chronically exposed to cold dry air and/or environmental pollutants found in indoor ice arenas. When airway surface liquid lost during the natural warming and humidification process of respiration is not replenished at a rate equal to the loss, the ensuing osmolarity change stimulates the release of inflammatory mediators and results in bronchospasm; this cascade of events is exacerbated by airway inflammation and airway remodelling. The acute EIB response is characterised by airway smooth muscle contraction, membrane swelling, and/or mucus plug formation. Evidence suggests that histamine, leukotrienes and prostanoids are likely mediators for this response. Although the presence of symptoms and a basic physical examination are marginally effective, objective measures of lung function should be used for accurate and reliable diagnosis of EIB. Diagnosis should include baseline spirometry, followed by an appropriate bronchial provocation test. To date, the best test to confirm EIB may simply be standard pulmonary function testing before and after high-intensity dry air exercise. A 10% post-challenge fall in forced expiratory volume in 1 second is used as diagnostic criteria. The goal of medical intervention is to limit EIB exacerbation and allow the athlete to train and compete symptom free. This is attempted through daily controller medications such as inhaled corticosteroids or by the prophylactic use of medications before exercise. In many cases, EIB is difficult to control. These and other data suggest that EIB in the elite athlete is in contrast with classic asthma.

Exercise in elite summer athletes: Challenges for diagnosis

BACKGROUND

There is a high prevalence of asthma and exercise-induced bronchoconstriction (EIB) in elite athletes when the diagnosis is based on symptoms and medication use. Objective measurements are now required by some sporting bodies to support a diagnosis of asthma or EIB to justify use of beta-agonists. Such measurements could include bronchial provocation with methacholine, with eucapnic voluntary hyperpnea (EVH) of dry air (a surrogate for exercise), or both.

OBJECTIVE

The aim of the study was to investigate the relationship between asthma symptoms and responses to methacholine and the EVH challenge in a group of unselected elite summer-sport athletes. The outcome would be to inform practitioners of a suitable objective approach to identifying those with asthma and EIB.

METHODS

Fifty elite summer-sport athletes with or without asthma were recruited from sporting teams and sports medicine centers throughout Melbourne, Australia. All subjects completed a respiratory questionnaire and, on separate days, underwent a bronchoprovocation challenge test with methacholine and EVH.

RESULTS

Forty-two subjects reported one or more respiratory symptoms in the past year, 9 had positive methacholine challenge results (mean PD(20) of 1.69 +/- 2.05 micromol), and 25 had positive EVH challenge results (mean fall in FEV(1) of 25.4% +/- 15%). Although all subjects with positive methacholine challenge results had positive EVH challenge results, methacholine had a negative predictive value of only 61% and a sensitivity of 36% for identifying those responsive to EVH.

CONCLUSION

These findings suggest that the pathogenesis of EIB in elite athletes might be different from that of asthma, and as such, neither symptoms nor the methacholine challenge test should be used exclusively for identifying EIB.

The asthmatic athlete, inhaled beta agonists, and performance

INTRODUCTION

The large increase in the number of athletes who apply to use inhaled beta agonists (IBAs) at the Olympic Games is a concern to the medical community. This review will examine the use of IBAs in the asthmatic athlete, the variability that exists between countries and sport, and outline a plan to justify the use of these medications.

DATA SOURCES

Much of this article is a result of an International Olympic Committee (IOC) Medical Commission-sponsored meeting that took place in May 2001. Records of the use of IBAs at previous Olympics were reviewed. MEDLINE Searches (PubMed interface) were performed using key words to locate published work relating to asthma, elite athletes, performance, treatment, and ergogenic aids.

MAIN RESULTS

Since 1984 there have been significant increases in the use of IBAs at the Olympic Games as well as marked geographical differences in the percentage of athletes requesting the use of IBAs. There are large differences in the incidence of IBA use between sports with a trend towards increased use in endurance sports. There are no ergogenic effects of any IOC-approved IBA given in a therapeutic dose.

CONCLUSIONS

In many cases, the prescription of IBAs to this population has been made on empirical grounds. Beginning with the 2002 Winter Games, athletes will be required to submit to the IOC Medical Commission clinical and laboratory evidence that justifies the use of this medication. The eucapnic voluntary hyperpnea test will be used to assess individuals who have not satisfied an independent medical panel of the need to use an IBA.