Exercise-induced asthma: is it the right diagnosis in elite athletes?

Asthma in elite athletes: pathogenesis, diagnosis, differential diagnoses, and treatment

Elite athletes have a high prevalence of asthma and exercise-induced bronchoconstriction. Although respiratory symptoms can be suggestive of asthma, the diagnosis of asthma in elite athletes cannot be based solely on the presence or absence of symptoms; diagnosis should be based on objective measurements, such as the eucapnic voluntary hyperpnea test or exercise test. When considering that not all respiratory symptoms are due to asthma, other diagnoses should be considered. Certain regulations apply to elite athletes who require asthma medication for asthma. Knowledge of these regulations is essential when treating elite athletes. This article is aimed at physicians who diagnose and treat athletes with respiratory symptoms. It focuses on the pathogenesis of asthma and exercise-induced bronchoconstriction in elite athletes and how the diagnosis can be made. Furthermore, treatment of elite athletes with asthma, anti-doping regulations, and differential diagnoses such as exercise-induced laryngomalacia are discussed.

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 bronchoconstriction in Tunisian elite athletes is underdiagnosed

Many studies have shown an increased risk of developing exercise-induced bronchoconstriction among the athletic population, particularly at the elite level. Subjective methods for assessing exercise-induced bronchoconstriction such as surveys and questionnaires have been used but have resulted in an underestimation of the prevalence of airway dysfunction when compared with objective measurements. The aim of the present study was to compare the prevalence of exercise-induced bronchoconstriction among Tunisian elite athletes obtained using an objective method with that using a subjective method, and to discuss the possible causes and implications of the observed discrepancy. As the objective method we used spirometry before and after exercise and for the subjective approach we used a medical history questionnaire. All of the recruited 107 elite athletes responded to the questionnaire about respiratory symptoms and medical history and underwent a resting spirometry testing before and after exercise. Post-exercise spirometry revealed the presence of exercise-induced bronchoconstriction in 14 (13%) of the elite athletes, while only 1.8% reported having previously been diagnosed with asthma. In conclusion, our findings indicate that medical history-based diagnoses of exercise-induced bronchoconstriction lead to underestimations of true sufferers.

The environment, the airway, and the athlete

OBJECTIVE

To review the interaction of environmental factors with host conditions, including atopy, the potential resulting impaired upper and lower airway function, and diagnostic and therapeutic considerations in the athlete.

DATA SOURCES

OVID, MEDLINE, and PubMed searches were performed cross-referencing the keywords asthma, athlete, atopy, bronchospasm, exercise, pollution, and rhinitis.

STUDY SELECTION

Articles were selected based on relevance to the subject matter.

RESULTS

Recent studies have yielded significant advances in our understanding of how intrinsic and extrinsic factors can potentially result in impaired function of the airways of athletes. Extrinsic factors include environmental exposure to temperature, humidity, aeroallergens, irritants, and pollution. Intrinsic factors include atopy, allergic rhinitis, asthma, and anatomical variants. These intrinsic and extrinsic factors can affect both the athlete's quality of life and athletic performance. However, uncertainty remains regarding relative contributions of these factors in explaining the high degree of bronchospasm seen in various populations of athletes with and without asthma, and no consensus exists regarding the most appropriate diagnostic and therapeutic modalities.

CONCLUSIONS

Great variability exists in the presentation, laboratory findings, diagnostic maneuvers, and response to therapeutic measures among populations of athletes in different sports and among individuals. An improved understanding of the unique exposures faced by athletes in different disciplines, of the available tests for pursuing the appropriate diagnosis, and of the available therapies will allow the allergist to provide clinical improvement and allow the athlete to find relief and achieve his/her full potential.

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.

Physical Activity in Childhood Asthma: Friend or Foe?

Physical activity has been considered as a double-edged sword for children with asthma. Children with asthma are recommended to participate in physical activities like their healthy nonasthmatic peers because regular physical activity positively affects psychological functioning, quality of life, morbidity, and aerobic fitness in children with asthma. However, uncontrolled asthma with ongoing exercise-induced bronchoconstriction may limit participation in sports, free play, and daily living. Observations also suggest that high-intensity exercise performed in cold air, seasonal allergens, pollutants, or respiratory virus infections may increase the risk for asthma in the highly active child. In contrast, a sedentary lifestyle has been highlighted as the explanation for the increased prevalence of asthma in the past decades. However, there is no consensus on whether a low level of physical activity increases the severity or risk of asthma. Use of asthma medications and good asthma control can make the conditions favorable for a physically active lifestyle and influence physical activity level and the level of aerobic fitness.

[Exercise-induced bronchoconstriction in non-asthmatic athletes]

INTRODUCTION

A new clinical entity, exercise-induced bronchoconstriction (EIB), has been recently defined which describes bronchoconstriction occurring in association with exercise in susceptible non-asthmatic persons.

STATE OF ART

There is considerable evidence that the pathogenesis of this condition is related to airway injury, due to prolonged hyperventilation and aggressive environmental factors. If the objective diagnostic tests are identical for the diagnosis of exercise induced asthma and EIB, the diagnoses are established differently, according to the high sensitivity of provocation by exercise "in the field" or the eucapnic voluntary hyperventilation provocation test.

PERSPECTIVES

Current pharmacological treatment is based upon the inhalation of ß2-agonists prior to exercise, but to be granted permission to use them, athletes are required to provide documentation of objective evidence of EIB. Therefore, the diagnostic pathway in athletes is essential and respiratory physicians need to know the specific features of this new clinical entity.

CONCLUSIONS

EIB distinct from the presence of asthma is prevalent in elite athletes and its determinants should be well known by their health care providers to assure an optimal management of this peculiar disease, in respect to drug doping regulations.

Desensitization of the cough reflex by exercise and voluntary isocapnic hyperpnea

Little is known about the effects of exercise on the sensory and cognitive aspects of coughing evoked by inhalation of tussigenic agents. The threshold for the cough reflex induced by inhalation of increasing nebulizer outputs of ultrasonically nebulized distilled water (fog), an index of cough reflex sensitivity, was assessed in twelve healthy humans in control conditions, during exercise and during voluntary isocapnic hyperpnea (VIH) at the same ventilatory level as the exercise. The intensity of the urge to cough (UTC), a cognitive component of coughing, was recorded throughout the trials on a linear scale. The relationships between inhaled fog nebulizer outputs and the correspondingly evoked UTC values, an index of the perceptual magnitude of the UTC sensitivity, were also calculated. Cough appearance was always assessed audiovisually. At an exercise level of 80% of anaerobic threshold, the median cough threshold was increased from a control value of 0.73 to 2.22 ml/min ( P < 0.01), i.e., cough sensitivity was downregulated. With VIH, the threshold increased from 0.73 to 2.22 ml/min ( P < 0.01), a similar downregulation. With exercise and VIH compared with control, mean UTC values at cough threshold were unchanged, i.e., control, 3.83 cm; exercise, 3.12 cm; VIH, 4.08 cm. The relationship of the fog nebulizer output/UTC value was linear in control conditions and logarithmic during both exercise and VIH. The perception of the magnitude of the UTC seems to be influenced by signals or sensations arising from exercising limb and thoracic muscles and/or by higher nervous (cortical) mechanisms. The results indicate that the adjustments brought into action by exercise-induced or voluntary hyperpnea exert inhibitory influences on the sensory and cognitive components of fog-induced cough.

Acute effects of beclomethasone on hyperpnea-induced bronchoconstriction

PURPOSE

The aim of this study was to assess whether a single high dose of beclomethasone dipropionate (BDP) could blunt mast cell activation and bronchoconstriction after eucapnic voluntary hyperpnea (EVH).

METHODS

In this model of exercise-induced bronchoconstriction (EIB), seven athletes with EIB and eight untrained subjects with mild asthma performed two EVH tests 5.5 h apart on the same day; the first challenge after inhalation of a placebo aerosol and the second 4 h after inhalation of BDP (1500 microg). Prechallenge and postchallenge pulmonary function and urinary excretion of the mast cell mediator 9alpha, 11beta-prostaglandin (PG) F2 were followed, as well as urinary excretion of the bronchoconstrictor leukotriene (LT) E4.

RESULTS

The EVH-induced bronchoconstriction was inhibited by BDP in both groups (P < 0.001): in athletes, mean +/- SEM percent fall in forced expiratory volume in 1 s was 22% +/- 4% after placebo versus 13% +/- 3% after BDP; in subjects with asthma, 23% +/- 4% after placebo versus 14 +/- 3% after BDP. This inhibition of airway response was associated with a significant reduction in the urinary excretion of 9alpha,11beta-PGF2 (P = 0.039) and LTE4 (P = 0.003) in both groups. Significant correlations were found between the percent fall in forced expiratory volume in 1 s and the increase in urinary excretion of both mediators 9alpha,11beta-PGF2 (r = 0.544, P = 0.002) and LTE4 (r = 0.380, P = 0.038) after EVH.

CONCLUSIONS

We conclude that a single dose of BDP has an acute protective effect on the bronchial response to hyperpnea in both untrained subjects with asthma and athletes with EIB. This effect was associated with decreased excretion of urinary mediators, suggesting that BDP blunted the mast cell activation.

Effects of chlorine and exercise on the unified airway in adolescent elite Scottish swimmers

BACKGROUND

Chlorine metabolites and high training load may produce exercise-induced bronchospasm (EIB) in elite swimmers. The aim of this study was to assess the combined effects of chlorine and exercise on the unified airway of adolescent elite swimmers.

METHODS

The Scottish Midlands District squad were assessed during an indoor pool session at the National Swimming Academy. Athletes trained at least 8 h per week. Subjects underwent tidal (T(NO)) and nasal (N(NO)) exhaled NO and peak nasal inspiratory flow (PNIF) pre and post a 2 h session. A physiological exercise challenge assessed EIB in n = 36 swimmers (>10% fall in forced expiratory volume in 1 s (FEV(1))).

RESULTS

Combined and free chlorine levels (mg/l) were 1.66 and 0.3 respectively. n = 36 swimmers (mean age 13.3 years) were assessed: n = 8 (22%) had known asthma; n = 13 (36%) had a positive physiological challenge; 18 (50%) complained of symptoms suggestive of EIB. n = 10/28 (36%) who did not have asthma were found to have a positive exercise challenge. There was no significant association between reported exercise symptoms and positive exercise test. There was no significant change in T(NO) or N(NO) for pre vs postexposure, irrespective of asthma diagnosis or AHR. n = 15 (42%) swimmers complained of worsening nasal symptoms postexposure, but only n = 7 (14%) had a demonstrable fall in PNIF (mean 33 l/min). No significant association was found between PNIF and symptoms.

CONCLUSIONS

Combined exposure to chlorine and exercise did not affect surrogate markers of inflammation in the unified airway. There was a high prevalence of undiagnosed EIB.

Short-duration accelerated breathing challenges affect phonation

OBJECTIVES/HYPOTHESIS

Inhaled air must be adequately humidified to prevent vocal fold drying, which is detrimental to phonation. The water content of inspired air is reduced by parameters, such as increased breathing rate and oral route. Accelerated oral breathing challenges induce airway dehydration and are posited to affect airway function. The primary objective of this study was to investigate whether accelerated oral breathing challenges are detrimental to phonation. The secondary objective of this study was to determine whether individuals at increased risk for developing voice problems (i.e., smokers) have greater adverse phonatory effects after accelerated breathing challenge than nonsmoking controls.

STUDY DESIGN

Prospective study with between-subjects, repeated-measures design.

METHODS

Female smokers (n = 12) and nonsmoking controls (n = 12) participated in this experimental study over 2 days that differed in ambient humidity. Phonation threshold pressures (PTP) were collected prior to and following short-term accelerated and habitual breathing challenges. Respiratory measures were collected during the challenges.

RESULTS

Short-term accelerated breathing challenges significantly increased PTP. This increase in PTP with accelerated breathing was transient and not significantly influenced by breathing route, ambient humidity, or smoking status. Likewise, respiratory measures were not affected by breathing route, ambient humidity, or smoking status.

CONCLUSIONS

During daily activities, such as exercise, individuals may engage in accelerated breathing for prolonged durations. This study demonstrates that even extremely short durations of accelerated breathing may affect phonation.

Prevalence of exercise-induced bronchoconstriction in teenage football players in Tunisia

BACKGROUND AND OBJECTIVES

Studies on exercise-induced bronchoconstriction (EIB) in team sports are lacking. The aim of this study was to screen for EIB among amateur teenage football players in Tunisia and to compare EIB prevalence between regions.

METHODS

One hundred ninety-six male football players (mean age [SD], 13.5 [0.5] yrs), practicing in three different cities of Tunisia (Tunis, Sousse and Sfax), underwent an outdoor free run of 7 minutes. Forced expiratory volume in one second (FEV subset1) was recorded prior to and at 0, 3, 5, 10, 15, 20 and 30 minutes after the run. Players were screened for EIB positivity defined as a greater than 10% decline in FEV subset1 from the resting value at any timepoint.

RESULTS

FEV1 decreased more than 10% in 30% of the players. EIB positivity was more common in Sfax (15.8%) than in Tunis (7.7%) (P=.03). Air humidity during the study was higher in Tunis.

CONCLUSION

EIB is prevalent among amateur teenage football players in Tunisia. The prevalence differs between regions and seems to be dependent on air humidity levels.

The respiratory health of swimmers

Regular physical activity is recognized as an effective health promotion measure. Among various activities, swimming is preferred by a large portion of the population. Although swimming is generally beneficial to a person's overall health, recent data suggest that it may also sometimes have detrimental effects on the respiratory system. Chemicals resulting from the interaction between chlorine and organic matter may be irritating to the respiratory tract and induce upper and lower respiratory symptoms, particularly in children, lifeguards and high-level swimmers. The prevalence of atopy, rhinitis, asthma and airway hyper-responsiveness is increased in elite swimmers compared with the general population. This may be related to the airway epithelial damage and increased nasal and lung permeability caused by the exposure to chlorine subproducts in indoor swimming pools, in association with airway inflammatory and remodelling processes. Currently, the recommended management of swimmers' respiratory disorders is similar to that of the general population, apart from the specific rules for the use of medications in elite athletes. Further studies are needed to better understand the mechanisms related to the development or worsening of respiratory disorders in recreational or competitive swimmers, to determine how we can optimize treatment and possibly help prevent the development of asthma.

Phonatory effects of airway dehydration: preliminary evidence for impaired compensation to oral breathing in individuals with a history of vocal fatigue

PURPOSE

Airway drying is detrimental to phonation and is posited to exacerbate vocal fatigue. However, limited research has demonstrated the adverse phonatory effects of dehydration in speakers reporting vocal fatigue. We compared the negative phonatory consequences of short-term oral breathing at low, moderate, and high humidity in individuals reporting a history of vocal fatigue and control participants.

METHOD

Females reporting a history of vocal fatigue (N = 8) and matched controls (N = 8) participated in a repeated-measures design over 3 different days.

RESULTS

Oral breathing at low and moderate humidity increased phonation threshold pressure (PTP) to a greater extent in individuals reporting a history of vocal fatigue as compared to controls. Conversely, PTP did not increase in either participant group after oral breathing in a humid environment. Perceived phonatory effort (PPE) ratings were poorly correlated with PTP.

CONCLUSIONS

The emergence of between-group differences in PTP at low and moderate but not high ambient humidity demonstrates that drying challenges might be detrimental to voice production in individuals with a history of vocal fatigue. Based on the phonatory effects of dehydration, we suggest that individuals reporting vocal fatigue may demonstrate impaired compensation to airway drying induced by short-term oral breathing.

Exercise and other indirect challenges to demonstrate asthma or exercise-induced bronchoconstriction in athletes

The prevalence of exercise-induced bronchoconstriction is reported to be high among recreational and elite athletes, yet diagnosis is often symptom-based. Indirect challenges such as the laboratory exercise challenge provide objective criteria for proper diagnosis and treatment. However, a standardized protocol using appropriate exercise intensity, duration, and dry air inhalation is often not implemented, and thus a false-negative test may result. This article reviews and describes the symptom-based diagnosis, the exercise challenge, and other indirect challenges such as eucapnic voluntary hyperpnea, hypertonic saline inhalation, and inhaled powdered mannitol as methods to diagnose and evaluate exercise-induced bronchoconstriction. Advantages and disadvantages of each diagnostic procedure are presented.

Airway injury as a mechanism for exercise-induced bronchoconstriction in elite athletes

Exercise-induced bronchoconstriction (EIB) is a consequence of evaporative water loss in conditioning the inspired air. The water loss causes cooling and dehydration of the airway surface. One acute effect of dehydration is the release of mediators, such as prostaglandins, leukotrienes, and histamine, that can stimulate smooth muscle, causing contraction and a change in vascular permeability. Inspiring cold air increases dehydration of the surface area and causes changes in bronchial blood flow. This article proposes that the pathogenesis of EIB in elite athletes relates to the epithelial injury arising from breathing poorly conditioned air at high flows for long periods of time or high volumes of irritant particles or gases. The evidence to support this proposal comes from many markers of injury. The restorative process after injury involves plasma exudation and movement of cells into the airways, a process repeated many times during a season of training. This process has the potential to expose smooth muscle to a wide variety of plasma- and cell-derived substances. The exposure to these substances over time can lead to an alteration in the contractile properties of the smooth muscle, making it more sensitive to mediators of bronchoconstriction. It is proposed that cold-weather athletes have airway hyperresponsiveness (AHR) to pharmacologic agents as a result of epithelial injury. In those who are allergic, AHR can also be expressed as EIB. The role of beta(2)-receptor agonists in inhibiting and enhancing the development of AHR and EIB is discussed.

Mechanisms of asthma in Olympic athletes--practical implications

Athletes' symptoms may only occur in extreme conditions, which are far from normal. Exercise may increase ventilation up to 200 l/min for short periods in speed and power athletes, and for longer periods in endurance athletes such as swimmers and cross-country skiers. Increasing proportions of young athletes are atopic, i.e. they show signs of IgE-mediated allergy which is, along with the sport event (endurance sport), a major risk factor for asthma and respiratory symptoms. Mechanisms in the etiology and clinical phenotypes vary between disciplines and individuals, and it may be an oversimplification to discuss athlete's asthma as a distinct and unambiguous disease. Nevertheless, the experience on Finnish Olympic athletes suggests at least two different clinical phenotypes, which may reflect different underlying mechanisms. The pattern of 'classical asthma' is characterized by early onset childhood asthma, methacholine responsiveness, atopy and signs of eosinophilic airway inflammation, reflected by increased exhaled nitric oxide levels. Another distinct phenotype includes late onset symptoms (during sports career), bronchial responsiveness to eucapnic hyperventilation test, but not necessarily to inhaled methacholine, and a variable association with atopic markers and nitric oxide. A mixed type of eosinophilic and neutrophilic airway inflammation seems to affect especially swimmers, ice-hockey players, and cross-country skiers. The inflammation may represent a multifactorial trauma, in which both allergic and irritant mechanisms play a role. There is a significant problem of both under- and overdiagnosing asthma in athletes and the need for objective testing is emphasized. Follow-up studies are needed to assess the temporal relationship between asthma and competitive sporting, taking better into account individual disposition, environmental factors (exposure), intensity of training and potential confounders.

Vocal fold epithelial response to luminal osmotic perturbation

PURPOSE

Dry-air challenges increase the osmolarity of fluid lining the luminal surface of the proximal airway. The homeostasis of surface fluid is thought to be essential for voice production and laryngeal defense. Therefore, the authors hypothesized that viable vocal fold epithelium would generate a water flux to reduce an osmotic challenge (150 mOsm mannitol) on the lumen. Bidirectional transepithelial water fluxes were measured in vocal folds exposed to physiologically realistic luminal osmotic perturbations in vitro.

METHOD

Thirty-six native ovine vocal folds were exposed to either luminal hyperosmotic or isosmotic perturbations. Vocal fold viability and water fluxes toward the lumen and into the mucosa were measured at prechallenge baseline and for 30 min after challenge.

RESULTS

Vocal fold electrophysiological viability was maintained for the duration of osmotic perturbation. Luminal osmotic exposure increased luminally directed transepithelial water fluxes in 60% of vocal folds. This increase was electrically silent, of short duration, and would not negate the osmotic gradient.

CONCLUSION

Ovine vocal fold epithelia detect osmotic perturbations to the luminal surface in vitro. This ability to detect and respond to changes in surface composition may be important in homeostatic regulation of vocal fold surface fluid during osmotic perturbations in respiration and phonation.

Autonomic control of bronchial blood flow and airway dimensions during strenuous exercise in sheep

BACKGROUND

During exercise and recovery the transient and steady-state changes in autonomic activity regulating lower airway blood flow and dimensions are unknown. The aim of this study was to define changes in bronchial blood flow (Q(br)) and dimensions during moderate and strenuous exercise, and to analyse the role of vagal and sympathetic nerves.

METHODS

Nine ewes (34-44kg) underwent left thoracotomy during general anaesthesia (thiopentone/isoflurane) and either (5 sheep=Group 1) a pulsed Doppler transducer was placed on the bronchial artery, or (4 sheep=Group 2) a pulsed Doppler transducer was placed on the bronchial artery, and transit-time and single crystal sonomicrometers were mounted on the left main bronchus. These measured continuously Q(br), bronchial circumference (Circ(br)) and wall thickness (Th(br)). Aortic pressure (P(a)) and central venous pressure catheters were placed in the superficial cervical artery and vein. Trained sheep exercised on a horizontal treadmill, i.e. Group 1, moderate exercise 2.2mph over 1.6, 6min recovery, for analysis of changes in Q(br) before and after cholinoceptor blockade; Group 2, strenuous exercise 4.4mph over 2, 10min recovery for analysis of changes in Q(br) and airway dimensions, before and after cholinoceptor plus alpha(1)-, alpha(2)-adrenoceptor blockade. beta-adrenoceptor systems were intact.

RESULTS

In Group 1 during moderate exercise P(a) and heart rate (HR) rose. Q(br) and blood flow conductance (C(br)) fell immediately to 83% (P<0.001) before returning toward resting levels, but fell when exercise ceased to 89% (P<0.01) before recovering. Prior cholinoceptor blockade abolished the immediate fall in Q(br) and C(br), but not the recovery vasoconstriction. Later in recovery the bronchial bed dilated progressively over 6min (P<0.05). In Group 2 during strenuous exercise P(a) and HR rose substantially. Q(br) and C(br) fell to 68% and 54% (P<0.001), respectively, and there was early vasoconstriction in recovery. Circ(br) fell immediately and remained at 93% (P<0.01), and did not recover fully when exercise ceased. Th(br) did not change during or after exercise. Prior cholinoceptor plus alpha-adrenoceptor block caused P(a) and Q(br) to fall slightly during exercise, but the bronchovascular constriction during and after exercise was abolished, as was circumferential shortening in the airway.

CONCLUSIONS

At exercise onset and steady-state, resetting the arterial baroreflex upward in sheep increases parasympathetic cholinergic vasoconstrictor activity and causes bronchial wall and bronchovascular smooth muscle contraction in concert with sympathetic adrenergic constriction of systemic vascular beds. Whether the known sigmoid baroreflex control of tracheal smooth muscle tension at rest is extended to tracheobronchial smooth muscle and its circulation during exercise is yet to be determined.

How does exercise cause asthma attacks?

PURPOSE OF REVIEW

To remind readers that evaporative water loss from the airway surface is the stimulus for exercise-induced bronchoconstriction. To emphasize that recruitment of the peripheral airways determines severity of exercise-induced bronchoconstriction. To draw attention to the potential for injury of the epithelium and for plasma exudation to contribute to the pathogenesis of exercise-induced bronchoconstriction in athletes. To emphasize that many inflammatory mediators are involved in exercise-induced bronchoconstriction and that some are found in both asthmatic and healthy subjects.

RECENT FINDINGS

That inflammatory mediators are released into the airways in response to exercise and can be measured by inducing sputum (histamine, cysteinyl leukotrienes) or collecting condensate from exhaled air (cysteinyl leukotrienes and adenosine). The concentration of mediators was reduced in response to a combination of loratadine and montelukast. Exercise is a stimulus for upregulating the genes coding for the 5-lipoxygenase pathway in healthy subjects.

SUMMARY

Dehydration of the airways results in release of mediators. The likely source of these mediators is the mast cell. Epithelial injury occurs in exercise-induced bronchoconstriction. The process of repair may contribute to the development of airway hyperresponsiveness in healthy subjects. Measuring the airway response to exercise, or a surrogate for exercise, as an indicator of airway hyperresponsiveness is warranted in patients with symptoms of asthma.

Rhinitis and asthma in athletes: an ARIA document in collaboration with GA2LEN

This consensus document is aimed at reviewing evidence that the rhinitis-asthma links have peculiar features in athletes. Beside a review of epidemological data on the high prevalence of rhinitis and asthma in athletes, the effects on intense physical exercise on the immune system and repiratory functions are discussed, with special reference to the role of allergens and pollutants. In extending the Allergic Rhinitis and its Impact on Asthma (ARIA) recommendations to athletes, the issue is addressed of adapting diagnosis and management to criteria set by the International Olympic Committee (IOC) and regulations adopted by the World Anti-Doping Agency (WADA).

Pulmonary disorders in the training room

For the athlete, not only can pulmonary disorders cause significant alterations in training schedules or even prolonged stoppages, they can be life-threatening. Infectious diseases such as acute bronchitis, influenza, and pneumonia conspire to disrupt exercise regimens. Pneumothorax, vocal cord dysfunction, and exercise-induced asthma may present diagnostic and treatment challenges. Obstructive sleep apnea not only causes disruptive symptoms but can be associated with significant cardiovascular morbidity and even mortality. This article addresses the most common pulmonary conditions athletes face and provides a framework for the diagnosis and treatment of these conditions.

Transient receptor potential vanilloid 4 regulates aquaporin-5 abundance under hypotonic conditions

Aquaporin-5 (AQP5) is expressed in epithelia of lung, cornea, and various secretory glands, sites where extracellular osmolality is known to fluctuate. Hypertonic aquaporin (AQP) induction has been described, but little is known about the effects of a hypotonic environment on AQP abundance. We report that, when mouse lung epithelial cells were exposed to hypotonic medium, a dose-responsive decrease in AQP5 abundance was observed. Hypotonic reduction of AQP5 was blocked by ruthenium red, methanandamide, and miconazole, agents that inhibit the cation channel transient receptor potential vanilloid (TRPV) 4 present in lung epithelial cells. Several observations indicate that TRPV4 participates in hypotonic reduction of AQP5, including a requirement for extracellular calcium to achieve AQP5 reduction; an increase in intracellular calcium in mouse lung epithelial (MLE) cells after hypotonic stimulation; and reduction of AQP5 abundance after addition of the TRPV4 agonist 4alpha-Phorbol-12,13-didecanoate (4alpha-PDD). Similarly, addition of hypotonic PBS to mouse trachea in vivo decreased AQP5 within 1 h, an effect blocked by ruthenium red. To confirm a functional interaction, AQP5 was expressed in control or TRPV4-expressing human embryonic kidney (HEK) cells. Hypotonic reduction of AQP5 was observed only in the presence of TRPV4 and was blocked by ruthenium red. Combined with earlier studies, these observations indicate that AQP5 abundance is tightly regulated along a range of osmolalities and that AQP5 reduction by extracellular hypotonicity can be mediated by TRPV4. These findings have direct relevance to regulation of membrane water permeability and water homeostasis in epithelia of the lung and other organs.

Protective effect of fish oil supplementation on exercise-induced bronchoconstriction in asthma

BACKGROUND

Previous research has demonstrated that fish oil supplementation has a protective effect on exercise-induced bronchoconstriction (EIB) in elite athletes, which may be attributed to its antiinflammatory properties. Since EIB in asthma involves proinflammatory mediator release, it is feasible that fish oil supplementation may reduce the severity of EIB in asthmatic subjects.

STUDY OBJECTIVES

To determine the efficacy of fish oil supplementation on severity of EIB in subjects with asthma.

DESIGN

Randomized, double-blind, crossover study.

SETTING

Lung function and exercise testing in a university research laboratory.

PATIENTS AND MEASUREMENTS

Sixteen asthmatic patients with documented EIB entered the study on their normal diet and then received either fish oil capsules containing 3.2 g of eicosapentaenoic acid and 2.0 g of docohexaenoic acid (fish oil diet, n = 8) or placebo capsules (placebo diet, n = 8) daily for 3 weeks. At the beginning of the study (normal diet) and at the end of each treatment phase, the following pre-exercise and postexercise measures were assessed: (1) pulmonary function; (2) induced sputum differential cell count percentage and proinflammatory eicosanoid metabolite (leukotriene C4 [LTC4]-leukotriene E4 [LTE4] and prostaglandin D2 [PGD2]) and cytokine (interleukin [IL]-1beta and tumor necrosis factor [TNF]-alpha) concentrations; and (3) eicosanoid metabolites leukotriene B4 (LTB4) and leukotriene B5 (LTB(5)) generation from activated polymorphonuclear leukocytes (PMNLs).

RESULTS

On the normal and placebo diet, subjects exhibited EIB. However, the fish oil diet improved pulmonary function to below the diagnostic EIB threshold, with a concurrent reduction in bronchodilator use. Induced sputum differential cell count percentage and concentrations of LTC4-LTE4, PGD2, IL-1beta, and TNF-alpha were significantly reduced before and following exercise on the fish oil diet compared to the normal and placebo diets. There was a significant reduction in LTB4 and a significant increase in LTB5 generation from activated PMNLs on the fish oil diet compared to the normal and placebo diets.

CONCLUSION

Our data suggest that fish oil supplementation may represent a potentially beneficial nonpharmacologic intervention for asthmatic subjects with EIB.

Influence of menstrual cycle phase on pulmonary function in asthmatic athletes

The main aim of this study was to investigate whether there is a relationship between menstrual cycle phase and exercise-induced bronchoconstriction (EIB) in female athletes with mild atopic asthma. Seven eumenorrheic subjects with regular 28-day menstrual cycles were exercised to volitional exhaustion on day 5 [mid-follicular (FOL)] and day 21 [mid-luteal (LUT)] of their menstrual cycle. Pulmonary function tests were conducted pre- and post-exercise. The maximal percentage decline in post-exercise forced expiratory volume in 1 s (FEV(1)) and forced expiratory flow from 25 to 75% of forced vital capacity (FEF(25-75%)) was significantly greater (P<0.05) on day 21 (mid-LUT phase) (-17.35+/-2.32 and -26.28+/-6.04%, respectively), when salivary progesterone concentration was highest, compared to day 5 (mid-FOL phase) (-12.81+/-3.35 and -17.23+/-8.20%, respectively), when salivary progesterone concentration was lowest. The deterioration in the severity of EIB during the mid-LUT phase was accompanied by worsening asthma symptoms and increased bronchodilator use. There was a negative correlation between the percent change in pre- to post-exercise FEV(1) and salivary progesterone concentration. However, no such correlation was found between salivary estradiol and the percentage change in pre- to post-exercise FEV(1). This study has shown for the first time that menstrual cycle phase is an important determinant of the severity of EIB in female athletes with mild atopic asthma. Female asthmatic athletes may need to adjust their training and competition schedules to their menstrual cycle and to consider the potential negative effects of the LUT phase of the menstrual cycle on exercise performance.

Physiological and pathophysiological down-regulation of cough

Recent clinical studies have emphasized the up-regulation (sensitization) of cough in pathological conditions of the airways. However there are also many situations where voluntary and reflex cough can be down-regulated. These include: (1) chemical stimulation of breathing by hypercapnia or hypoxia or both, establishing that cough sensitivity can be inversely related to drive to breathing; (2) voluntary inhibition of cough, probably similar in mechanism to the depression of cough that can be induced by hypnosis and other branches of alternative medicine; (3) the placebo effect of many antitussive treatments; (4) sleep; (5) general anaesthesia; (6) central nervous disorders such as coma, stroke, Parkinson's disease and several other conditions where the defect in the protective reflexes may lead to aspiration pneumonia; (7) increased activity in various afferent inputs from viscera in the thorax and abdomen; (8) a number of bronchopulmonary clinical disorders. The list is long, but regrettably the nervous mechanisms of these down-regulations have been little studied. In addition there are a number of situations, such as exercise, coitus, talking and singing which, while important to coughing humans, have been not investigated in relation to cough. Most of the studies have been with experimental animals, and their extension to human research is desirable. In view of the importance of cough and other defensive reflexes in maintaining human well-being, far more research is needed. The field is wide-open.

Identifying exercise-induced bronchospasm: treatment hinges on distinguishing it from chronic asthma

Exercise-induced bronchospasm (EIB) is an often-undiagnosed but common problem affecting both recreational and elite athletes. Although exercise can trigger exacerbation of chronic asthma, EIB should not be confused with the chronic inflammatory disease. In this article, Drs Hermansen and Kirchner review the incidence, diagnosis, and treatment of EIB and explain how to distinguish EIB from chronic asthma.

Asthma, airway inflammation and treatment in elite athletes

Highly trained athletes are repeatedly and strongly exposed to cold air during winter training and to many inhalant irritants and allergens all year round. Asthma occurs most commonly in athletes engaging in endurance events such as cross-country skiing, swimming, or long-distance running. As well as the type of training, a major risk factor is atopic disposition. A mixed type of eosinophilic and neutrophilic airway inflammation has been shown to affect elite swimmers, ice-hockey players, and cross-country skiers. The inflammation may represent a form of repeated thermal, mechanical, or osmotic airway trauma resulting in a healing or remodelling process. Elite athletes commonly use antiasthma drugs to treat exercise-induced bronchial symptoms. Only a few controlled studies have been conducted on the effects of antiasthma drugs on asthma symptoms, bronchial hyperresponsiveness and airway inflammation in elite athletes. Inhaled beta(2)-adrenoceptor agonists are effective against exercise-induced bronchospasm. In contrast, airway inflammation, bronchial hyperresponsiveness and symptoms have responded poorly to inhaled corticosteroids and leukotriene antagonists. As discontinuing high-level exercise has proved effective in reducing eosinophilic airway inflammation, exercise or training should be restricted in athletes having troublesome symptoms and sputum eosinophilia. Switching training to less irritating environments should be considered whenever possible. It appears to be difficult to change the 'natural course' of asthma in athletes by anti-inflammatory treatment.

Responses and limitations of the respiratory system to exercise

During maximal exercise, the gas exchange function of the lung is challenged because of the major cardiopulmonary changes that must occur to meet the increased metabolic demands imposed by exercise. In healthy untrained young adults, the respiratory system is able to meet these demands imposed on it during maximal exercise by implementing several key mechanisms. Nonetheless, there are several exceptional cases in which the lung is unable to accommodate the demands of exercise because of vascular or airway limitations.

Diacylglycerol-Containing Docosahexaenoic Acid in Acyl Chain Modulates Airway Smooth Muscle Tone

We synthesized and assessed the role of a diacylglycerol (DAG)-containing docosahexaenoic acid (DHA), that is, 1-stearoyl-2-docosahexaenoyl-sn-glycerol (SDHG), in the contraction of guinea pig airway smooth muscle (ASM). We compared its action with 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG) and 1,2-dioctanoyl-sn-glycerol (1,2-DiC8), a stable DAG analog. The three DAGs (SAG, SDHG, and 1,2-DiC8) induced reversible concentration-dependent contraction of ASM. SDHG induced higher guinea pig ASM contraction than did SAG and 1,2-DiC8. The effects of SDHG were blocked, to different extents, by nifedipine (L-type Ca2+ channel blocker). By employing GF-109203X (protein kinase C [PKC] inhibitor) and lanthanum (La3+), a nonselective cation channel blocker, we observed that SDHG evoked ASM contractile response via PKC-dependent and PKC-independent (but Ca2+-dependent) pathways. Interestingly, SAG exerted its action only by increasing [Ca2+]i and did not require PKC activation. To probe the implication of calcium mobilization, we employed thapsigargin (TG), which also induced ASM contraction in a calcium-dependent manner. SDHG and 1,2-DiC8, in a PKC-dependent manner, induced the phosphorylation of CPI-17 (myosin light chain phosphatase inhibitor of 17 kD). Furthermore, SAG and TG failed to phosphorylate CPI-17 in ASM cells. Our results suggest that different DAG species, produced during a dietary supplementation with fatty acids, could modulate the reactivity of airway smooth muscles in a PKC-dependent and -independent manner, and hence, may play a critical role in health and disease.

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.

Prevalence of exercise-induced bronchospasm in long distance runners trained in cold weather

We investigated whether regular training in cold weather has an effect on the development of exercise-induced bronchospasm. Nineteen sedentary males and 20 male long distance runners who were regularly training in Erzurum participated in this study. They had no history of asthma, atopy or allergic rhinitis. Pre- and post-exercise spirometry was performed in the participants in room temperature. EIB was defined as at least a > or =10% fall in FEV1 or a > or =15% fall in FEF(25-75%) or a > or =25% fall in PEFR. EIB was established in 7 of 20 athletes and in 1 of 19 sedentaries. Prevalence of EIB will be higher even if it is established in room temperature when training for the sports like long distance running which is not a cold weather sport. We conclude that it will be more convenient to establish EIB in room temperature and in the laboratory since the exercise test and spirometry can be performed more accurately under more standard conditions.

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.

Exercise-induced bronchoconstriction: pathogenesis

There is still active debate on the acute mechanism of exercise-induced bronchoconstriction (EIB). Although it is unlikely that vasoconstriction and hyperemia of the bronchial vasculature are essential events for EIB, it is likely that this vasculature enhances the airway response to dehydration and contributes to the pathogenesis of EIB, particularly in elite athletes. Accumulating evidence suggests that airway smooth muscle (ASM) becomes more sensitive as a result of repeated exposure to bulk plasma in response to airway injury from dehydration. Recent evidence also demonstrates sufficient concentrations of mediators that could affect ASM. Paradoxically, mediator release from mast cells may be enhanced and their contractile effects greater when beta(2)-receptor agonists are taken daily. The effect of drugs that have the potential to reduce microvascular leak and reduce or inhibit release or action of these mediators needs to be investigated in elite athletes.

Bronchial Hyperresponsiveness, Airway Inflammation, and Airflow Limitation in Endurance Athletes

BACKGROUND

Whereas a high prevalence of bronchial abnormalities has been reported in endurance athletes, its underlying mechanisms and consequences during exercise are still unclear.

STUDY OBJECTIVES

The purpose of this study was to assess the following: (1) bronchial responsiveness to methacholine and to exercise; (2) airway inflammation; and (3) airflow limitation during intense exercise in endurance athletes with respiratory symptoms.

DESIGN

Cross-sectional observational study.

SETTING

Lung function and exercise laboratory at a university hospital.

PATIENTS AND MEASUREMENTS

Thirty-nine endurance athletes and 13 sedentary control subjects were explored for the following: (1) self-reported respiratory symptoms; (2) bronchial hyperresponsiveness (BHR) to methacholine and exercise; (3) airflow limitation during intense exercise; and (4) bronchial inflammation using induced sputum and nitric oxide (NO) exhalation.

RESULTS

Fifteen athletes (38%) showed BHR to methacholine and/or exercise in association with bronchial eosinophilia (mean [+/- SD] eosinophil count, 4.1 +/- 8.5% vs 0.3 +/- 0.9% vs 0%, respectively), higher NO concentrations (19 +/- 10 vs 14 +/- 4 vs 13 +/- 4 parts per billion, respectively), a higher prevalence of atopy, and more exercise-induced symptoms compared with non-hyperresponsive athletes and control subjects (p < 0.05). Furthermore, airflow limitation during intense exercise was observed in eight athletes, among whom five had BHR. Athletes with airflow limitation reported more symptoms and had FEV1, FEV1/FVC ratio, and forced expiratory flow at midexpiratory phase values of 14%, 9%, and 29%, respectively, lower compared with those of nonlimited athletes (p < 0.05).

CONCLUSION

BHR in endurance athletes was associated with the criteria of eosinophilic airway inflammation and atopy, whereas airflow limitation during exercise was primarily a consequence of decreased resting spirometric values. Both BHR and bronchial obstruction at rest with subsequent expiratory flow limitation during exercise may promote respiratory symptoms during exercise in athletes.

Asthma and panic in young adults: a 20-year prospective community study

RATIONALE

Psychologic factors are increasingly recognized to influence the onset and course of asthma. Previous cross-sectional community-based studies have provided evidence for a relatively specific association between asthma and panic.

OBJECTIVES

To examine concurrent and longitudinal associations between asthma and panic in young adults.

MEASUREMENTS AND MAIN RESULTS

Prospective community-based cohort study of young adults (n = 591) followed between ages 19 and 40. Information was derived from six subsequent semistructured diagnostic interviews conducted by professionals. Cross-sectionally (over the whole study period), asthma was more strongly associated with panic disorder (odds ratio [OR] = 4.0; 95% confidence interval [CI], 1.7, 9.3) than with any panic, which included panic disorder and panic attacks (OR = 2.1; 95% CI, 1.1, 4.5). Longitudinally, after adjusting for potentially confounding variables, active asthma predicted subsequent panic disorder (OR = 4.5; 95% CI, 1.1, 20.1), and the presence of panic disorder predicted subsequent asthma activity (OR = 6.3; 95% CI, 2.8, 14.0). Asthma predicted any panic (OR = 2.7; 95% CI, 1.1, 7.1), whereas any panic did not predict subsequent asthma activity. Associations were stronger in smokers than in nonsmokers, and stronger in women than in men. Smoking, early-childhood anxiety, and a family history of allergy were important confounders of the asthma-panic association.

CONCLUSIONS

This is the first long-term follow-up study on asthma and panic. It showed dose-response-type relationships between panic and asthma, and bidirectional longitudinal associations between the two conditions. It provided evidence for familial factors and smoking as possible shared etiologic explanations.

Exercise testing in pediatrics

This article discusses exercise physiology and its application in the pediatric population. This article discusses exercise physiology and its application in the pediatric population. The authors briefly review the normal physiologic response to exercise. They then discuss populations in which exercise testing is most useful, the indications and contraindications for graded exercise, and the usual parameters that are measured during testing. Finally, the authors review some of the recent data on exercise performance in specific pediatric populations.

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.

Identifying exercise-induced bronchospasm. Treatment hinges on distinguishing it from chronic asthma

Exercise-induced bronchospasm (EIB) is an often-undiagnosed but common problem affecting both recreational and elite athletes. Although exercise can trigger exacerbation of chronic asthma, EIB should not be confused with the chronic inflammatory disease. In this article, Drs Hermansen and Kirchner review the incidence, diagnosis, and treatment of EIB and explain how to distinguish EIB from chronic asthma.

Fish oil supplementation reduces severity of exercise-induced bronchoconstriction in elite athletes

In elite athletes, exercise-induced bronchoconstriction (EIB) may respond to dietary modification, thereby reducing the need for pharmacologic treatment. Ten elite athletes with EIB and 10 elite athletes without EIB (control subjects) participated in a randomized, double-blind crossover study. Subjects entered the study on their normal diet, and then received either fish oil capsules containing 3.2 g eicosapentaenoic acid and 2.2 g docohexaenoic acid (n-3 polyunsaturated fatty acid [PUFA] diet; n = 5) or placebo capsules containing olive oil (placebo diet; n = 5) taken daily for 3 weeks. Diet had no effect on preexercise pulmonary function in either group or on postexercise pulmonary function in control subjects. However, in subjects with EIB, the n-3 PUFA diet improved postexercise pulmonary function compared with the normal and placebo diets. FEV1 decreased by 3 +/- 2% on n-3 PUFA diet, 14.5 +/- 5% on placebo diet, and 17.3 +/- 6% on normal diet at 15 minutes postexercise. Leukotriene (LT)E4, 9alpha, 11beta-prostaglandin F2, LTB4, tumor necrosis factor-alpha, and interleukin-1beta, all significantly decreased on the n-3 PUFA diet compared with normal and placebo diets and after the exercise challenge. These data suggest that dietary fish oil supplementation has a markedly protective effect in suppressing EIB in elite athletes, and this may be attributed to their antiinflammatory properties.

Airway cells after swimming outdoors or in the sea in nonasthmatic athletes

BACKGROUND

Marathon runners and elite swimmers showed increased inflammatory cells in the airways at baseline. Although airway neutrophils increase further after a marathon race, the airway response to swimming is unknown. The aim of this study was to assess the effects of swimming on airway cells. To avoid the concomitant effects of chronic exposure to chlorine, the study was conducted in seven nonasthmatic swimmers [mean age (SD): 23.3 +/- 7.7 yr, training: 32 +/- 15 km.wk-1] habitually training in an outdoor pool (OP), i.e., a low-chlorine environment.

METHODS

Spirometry, exhaled nitric oxide (NO), induced sputum, and peripheral blood samples were obtained at baseline, after a 5-km trial in OP, and after a 5-km race in the sea (S), i.e., hypertonic airway exposure.

RESULTS

Airway neutrophil differential counts at baseline were higher in swimmers than in sedentary controls (N = 10), but cell counts, neutrophil elastase, and eosinophil cationic protein were unaffected by 5-km swimming. After swimming, L-selectin expression on airway cells decreased, suggesting exercise-induced cell mobilization into the airways and/or direct effects of hyperventilation on airway cells. After S, airway eosinophil differential counts increased slightly. Exhaled NO concentration was 19 +/- 6 ppb at baseline, 8 +/- 4 ppb after OP, and 21 +/- 7 ppb after S (P < 0.005 for OP vs baseline and S).

CONCLUSIONS

In swimmers not chronically exposed to high chlorine concentrations, data obtained at baseline suggest a direct relationship between airway neutrophilia and endurance training. The low L-selectin expression by airway cells postexercise suggests hyperventilation-induced cell recruitment or modulation of cell function. Hypertonic exposure of airways during exercise may slightly increase airway eosinophils and exhaled NO. Overall, 5-km swimming exerted smaller effects on airway cells than running a marathon.

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.

Effect of rapid eye movement sleep deprivation on allergen-induced airway responses in a rat model of asthma

BACKGROUND

Nocturnal airway narrowing is a common characteristic of asthma that remains poorly understood. Sleep itself or rapid eye movement (REM) sleep has been suspected to play a role in the etiology of nocturnal asthma; however, only inconsistent findings have so far been produced. The purpose of this study was to examine the effect of sleep deprivation, particularly REM sleep, using the classical platform (flowerpot) method on asthmatic responses in a rat model of asthma, in a situation of immobilization stress.

METHODS

After the rats had been randomly divided into three groups of 9 including (1) a caged control group, (2) a large (sham) platform group, and (3) a small platform group, we investigated the effect of REM sleep deprivation over a 72-hour period on both the antigen-induced immediate asthmatic response (IAR) and late asthmatic response (LAR) including the changes of stress hormones.

RESULTS

The small platform group showed significantly lower plasma histamine levels and higher plasma adrenaline levels during the IAR compared to the control group (p < 0.05). The number of eosinophils in either the bronchoalveolar lavage fluid or the bronchial lamina propria during the LAR in the small platform group was reliably suppressed compared to the other groups (p < 0.05). No significant differences were found in the plasma corticosterone and noradrenaline levels among the three groups, irrespective of the phase of the asthmatic response.

CONCLUSIONS

Our results indicate that REM sleep contributes to nocturnal asthma, possibly due to an alteration of the sympathetic nervous function.