Re-examination of the late asthmatic response to exercise

Role of cells and mediators in exercise-induced bronchoconstriction

A susceptible group of subjects with asthma develops airflow obstruction in response to the transfer of water out of the airways during exercise. The transfer of water or the challenge with a hypertonic solution serves as a strong stimulus to the airway epithelium. Susceptible subjects have epithelial shedding into the airway lumen, and airway inflammation that leads to the overproduction of leukotrienes and other eicosanoids following exercise challenge. The sensory nerves of the airways may serve as a critical link that mediates the effect of eicosanoids, leading to bronchoconstriction and mucus production in response to exercise challenge.

Cold air-induced late-phase bronchoconstriction in horses

REASON FOR PERFORMING STUDY

Inspired air is warmed to body temperature and fully humidified by the upper airway mucosa under normal resting conditions. This conditioning process may not be completed by the upper airways during conditions of increased minute ventilation or when the inspired air is unusually cold, resulting in cooling and desiccation of lower respiratory surfaces. Excess heat and water loss from intrapulmonary airways is believed to be the provocative stimulus for exercise-induced bronchoconstriction (occurring immediately after exercise) and associated late phase airway obstruction (occurring a few hours after exercise).

HYPOTHESIS

Exercise while breathing cold air results in airway obstruction in horses.

METHODS

Eight healthy horses performed a 15 min submaximal exercise challenge in a random crossover design. Independent variable was inspired air temperature during the challenge (25 or -5 degrees C). The dependent variables were total respiratory impedance, resistance, and reactance at 5, 24 and 48 h post exercise challenge, expressed as a percentage of the prechallenge baseline.

RESULTS

No significant effect of inspired air temperature was found on any respiratory mechanical parameter 5 h after exercise challenge. However, cold inspired air was associated with higher respiratory impedance and resistance 48 h after the exercise challenges.

CONCLUSIONS

These findings support the hypothesis that submaximal exercise while breathing subfreezing air can adversely affect respiratory mechanical properties in normal horses. However, the timecourse for development of abnormal respiratory mechanical properties is longer than that reported in other mammals.

CLINICAL RELEVANCE

Exercise in cold weather may be a common cause of lower airway disease in horses.

Exercise-Induced Asthma: An Update

Exercise-induced asthma (E.I.A) affects 12–16% of the general population and most of the patients affected by extrinsic or intrinsic asthma. Surprisingly, also a high percentage of professional and Olympic athletes are affected, showing that E.I.A. does not impair physical activity, whereas endurance sports bear a higher risk than the others. The mast cell role, late asthmatic responses, diagnosis, therapy, theories and data about immunological parameters in sports are taken into consideration in this review.

Exercise-induced bronchoconstriction in children: montelukast attenuates the immediate-phase and late-phase responses

BACKGROUND

Montelukast, a leukotriene receptor antagonist, attenuates exercise-induced bronchoconstriction. We and others have shown that there is a late-phase response 3 to 8 hours after exercise in a subset of asthmatic patients.

OBJECTIVE

We sought to evaluate the protective effect of montelukast on immediate-phase and late-phase responses after exercise challenges.

METHODS

Twenty-two atopic asthmatic children aged 7 to 16 years with reproducible exercise-induced bronchoconstriction (minimum of 15% decrease of FEV(1) from baseline) were enrolled in this placebo-controlled crossover study. Exercise challenges were performed while breathing cold dry air, and FEV(1) measurements were taken up to 480 minutes after exercise. Patients underwent exercise challenges on a screening day and 1 week after placebo treatment. Subsequently, after a week with no treatment, pulmonary function was assessed after breathing dry cold air (control day). Finally, an exercise challenge was carried out after a week of treatment with montelukast.

RESULTS

Reproducible late-phase reactions occurred in 5 of 22 patients, which correlated with the extent of the immediate response (P <.05). After 1 week of treatment with montelukast, a significant decrease of immediate responses was observed. Montelukast treatment compared with placebo was associated with a lower mean maximum decrease of FEV(1) (mean +/- SEM: 17.3% +/- 2.4% and 35.1% +/- 2.6%, respectively), decrease of the area above the curve (267.8% +/- 42.7%/min and 868.0% +/- 103.8%/min, respectively), and shorter time for recovery (6.9 +/- 1.1 minutes and 30.9 +/- 4.0 minutes, respectively; P <.05). Treatment with montelukast also abolished late-phase responses.

CONCLUSION

Once daily treatment with oral montelukast attenuated the immediate-phase response and abolished the late-phase response induced by means of exercise challenge in asthmatic children.

Modeling the acute- and late-phase responses to peripheral airway cooling and desiccation

Acute bronchoconstriction after isocapnic hyperpnea can be produced in most asthmatic individuals. However, the existence of a late-phase response is less certain. We used a canine model of isocapnic hyperpnea to test the hypothesis that this discrepancy is due to differences in the challenge threshold for the responses. Acute-phase and late-phase bronchoconstriction was measured in nine dogs after peripheral airway exposure to unconditioned air. Additionally, bronchoalveolar lavage fluid (BALF) was obtained during the late-phase response. The acute-phase response was a polynomial function with a decreasing slope at higher challenges, whereas the late-phase response suggested that a minimum threshold of challenge severity was needed to produce late-phase bronchoconstriction. BALF leukocyte and eicosanoid concentrations had linear relationships with challenge severity. Our data support the hypothesis that acute- and late-phase posthyperpnea responses have different dose-response relationships, a fact that may explain the frequent lack of a late-phase response. However, our data suggest that mild inflammation can be induced with relatively lower challenge severity.

Eicosanoids modulate hyperpnea-induced late phase airway obstruction and hyperreactivity in dogs

A canine model of exercise-induced asthma was used to test the hypothesis that the development of a late phase response to hyperventilation depends on the acute production of pro-inflammatory mediators. Peripheral airway resistance, reactivity to hypocapnia and aerosol histamine, and bronchoalveolar lavage fluid (BALF) cell and eicosanoid content were measured in dogs approximately 5 h after dry air challenge (DAC). DAC resulted in late phase obstruction, hyperreactivity to histamine, and neutrophilic inflammation. Both cyclooxygenase and lipoxygenase inhibitors administered in separate experiments attenuated the late phase airway obstruction and hyperreactivity to histamine. Neither drug affected the late phase inflammation nor the concentrations of eicosanoids in the BALF obtained 5 h after DAC. This study confirms that hyperventilation of peripheral airways with unconditioned air causes late phase neutrophilia, airway obstruction, and hyperreactivity. The late phase changes in airway mechanics are related to the hyperventilation-induced release of both prostaglandins and leukotrienes, and appear to be independent of the late phase infiltration of inflammatory cells.

Keeping children with exercise-induced asthma active

Exercise-induced bronchospasm, exercise-induced bronchoconstriction, and exercise-induced asthma (EIA) are all terms used to describe the phenomenon of transient airflow obstruction associated with physical exertion. It is a prominent finding in children and young adults because of their greater participation in vigorous activities. The symptoms shortness of breath, cough, chest tightness, and wheezing normally follow the brief period of bronchodilation present early in the course of exercise. Bronchospasm typically arises within 10 to 15 minutes of beginning exercise, peaks 8 to 15 minutes after the exertion is concluded, and resolves about 60 minutes later, but it also may appear during sustained exertion. EIA occurs in up to 90% of asthmatics and 40% of patients with allergic rhinitis; among athletes and in the general population its prevalence is between 6% and 13%. EIA frequently goes undiagnosed. Approximately 9% of individuals with EIA have no history of asthma or allergy. Fifty percent of children with asthma who gave a negative history for EIA had a positive response to exercise challenge.6 Among high school athletes, 12% of subjects not considered to be at risk by history or baseline spirometry tested positive. Before the 1984 Olympic games, of 597 members of the US team, 67 (11%) were found to have EIA. Remarkably, only 26 had been previously identified, emphasizing the importance of screening for EIA even in well-conditioned individuals who appear to be in excellent health. The severity of bronchospasm in EIA is related to the level of ventilation, to heat and water loss from the respiratory tree, and also to the rate of airway rewarming and rehydration after the challenge. Postexercise decrease in the peak expiratory flow rate of normal children may be as much as 15%; therefore, only a decrease in excess of 15% should be viewed as diagnostic. EIA is usually provoked by a workload sufficient to produce 80% of maximum oxygen consumption; however, in severe asthmatics even minimal exertion may be enough to produce symptoms. Patients with normal lung function at rest may have severe air flow limitation induced by exercise,10 and as many as 50% of patients who are well-controlled with inhaled corticosteroids still exhibit EIA. A challenge of sufficient magnitude will provoke EIA in all patients with asthma. PHARMACOLOGIC THERAPY: Exercise, unlike exposure to allergens, does not produce a long-term increase in airway reactivity. Accordingly, patients whose symptoms manifest only after strenuous activity may be treated prophylactically and do not require continuous therapy. Most asthma medications, even some unconventional ones such as heparin, furosemide, calcium channel blockers, and terfenadine, given before exercise, suppress EIA. McFadden accounts for the efficacy of these disparate classes of drugs by their potential effect on the bronchial vasculature that modulates the cooling and/or rewarming phases of the reaction. Short-acting -agonists provide protection in 80% to 95% of affected individuals with insignificant side effects and have been regarded for many years as first-line therapy. Two long-acting bronchodilators, salmeterol and formoterol, have been found effective in the prevention of EIA.18-21 A single 50-microg dose of salmeterol protects against EIA for 9 hours; its duration appears to wane in the course of daily therapy. Cromolyn sodium is highly effective in 70% to 87% of those diagnosed with EIA and has minimal side effects. Nedocromil sodium provides protection equal to that of cromolyn in children. Children commonly engage in unplanned physical activity and sometimes are not allowed to carry their own medication. Thus, a simple long-acting regimen given at home is likely to be more effective than short-acting drugs that must be administered in a timely manner. Although the 12-hour protection by salmeterol reported by Bronsky et al may not persist with continued use, the 9-hour duration of action is

Prevalence and characteristics of exercise-induced asthma in children

We have evaluated the prevalence and the characteristics of exercise-induced asthma (EIA) in a group of 71 patients with a prior history of mild, moderate or severe asthma (42 males and 29 females), aged 6-16 years-old. Measurements of the forced expiratory volume in 1 second (FEV1) were obtained before and at regular intervals up to 8 hours following exercise. As a control, the same patients were evaluated at similar time intervals on another day when they had not been submitted to an exercise challenge. Using pre-exercise FEV1 values as the reference, 32 patients (45.1%) had a positive exercise challenge, defined as a fall in FEV1 value equal to or greater than 15% from baseline following exercise. Among the patients with a positive exercise challenge, the majority (23/32, 71.8%) had an immediate response alone, with no significant changes in FEV1 within the 8-hour follow-up. However, a subgroup of patients (9/32, 28.1%) had both an immediate and a late-phase response to exercise. During the control day, no significant fall in FEV1 were observed. In keeping with previous investigations, no correlation was found between a history of EIA and a positive exercise challenge in the present study. Positive exercise challenges were found more frequently among patients with moderate and severe asthma than patients with mild asthma.

The occurrence of late asthmatic response to exercise after allergen challenge

BACKGROUND

The determinants of late asthmatic responses to exercise remain unknown. It has been reported that they may develop in some adult subjects with asthma following a late asthmatic response to allergen.

OBJECTIVE

We intended to corroborate this finding in children with asthma and to investigate which aspect of airway responses to allergen is associated with late asthmatic responses to exercise.

METHODS

We studied 17 children with allergic asthma, who showed late asthmatic responses to inhaled allergen (Dermatophagoides pteronyssinus). Each underwent an exercise challenge test two days before (pre-allergen) and two days after (postallergen) an allergen inhalation challenge. FEV1 was measured at regular intervals up to ten hours after each challenge. Methacholine PC20 was measured before the allergen challenge and before the postallergen exercise challenge.

RESULTS

After the pre-allergen exercise test, all the subjects showed isolated early asthmatic responses. After the postallergen exercise test, seven showed dual responses (early and late asthmatic responses) (group I) and the remaining ten showed isolated early asthmatic responses (group II). Bronchial responses to pre-allergen exercise or inhaled allergen and the severity of early asthmatic responses to postallergen exercise were similar in groups I and II. Neither before allergen inhalation nor before the postallergen exercise was methacholine PC20 different between the two groups. Methacholine dose shift caused by allergen challenge, however, was significantly greater in group I than in group II (-2.00+/-0.39 versus -1.36+/-0.53 doubling doses; P < .05). There was significant correlation between the dose shift and the magnitude of late response to the postallergen exercise in the whole group (r = 0.51, P < .05).

CONCLUSION

Late asthmatic responses to exercise may develop in some children with asthma following a late asthmatic response to allergen. This phenomenon was related neither to the baseline nor to postallergen methacholine PC20 but to the extent of increased sensitivity to methacholine caused by allergen challenge.

Late asthmatic response in exercise-induced asthma

BACKGROUND

There is a controversy over the occurrence of a late asthmatic response during exercise-induced asthma. While some workers have documented such a response as a genuine phenomenon, others have attributed this to drug withdrawal.

OBJECTIVES

We carried out the present study to investigate whether a late asthmatic response occurs during exercise-induced asthma as a genuine event and, if so, what are the factors which determine its occurrence.

METHODS

Sixteen, clinically stable asthmatic patients with laboratory-proven exercise-induced asthma underwent a standardized exercise challenge on a bicycle ergometer. The airway response to exercise was studied by spirometry to measure FEV1. Spirometry was carried out before the exercise, at 4, 8, 15, 30, and 60 minutes, and then hourly for the next 7 hours. Spirometry was also done repeatedly as above on a non-exercise control day, four to seven days earlier.

RESULTS

Eight (50%) subjects developed a second fall of greater than 10% in FEV1, three to eight hours after recovery from the early response. The late fall in FEV1 after exercise was significantly greater than the spontaneous decay of lung function at the corresponding clocktime on the non-exercise control day. The dual responders did not differ from those with isolated early responses with respect to age, duration and severity of asthma, treatment requirements, peripheral blood eosinophilia, and atopic status. Baseline FEV1 and maximum fall in FEV1 during the early response, and the rate of its development and recovery from it were also similar. Among the dual responders, the late response was not related to the baseline FEV1 or to the intensity of the early response.

CONCLUSIONS

A late asthmatic response is a genuine phenomenon in exercise-induced asthma. Its occurrence cannot however be predicted by any clinical or physiologic factors.

Comparison between allergen-induced and exercise-induced asthma with respect to the late asthmatic response, airway responsiveness, and Creola bodies in sputum

BACKGROUND

The difference between allergen-induced asthma and exercise-induced asthma with respect to the late asthmatic response and airway responsiveness has not been well elucidated.

OBJECTIVE

We compared the incidence of late asthmatic response, the changes in airway responsiveness, the degree of epithelial desquamation, and the activation of eosinophils in the airways after induction of allergen-induced asthma and exercise-induced asthma.

METHODS

Allergen-induced asthma or exercise-induced asthma was provoked in asthmatic patients, and sputum was collected before challenge and at the immediate asthmatic response and the late asthmatic response. Clusters of columnar epithelial cells in sputum (Creola bodies) were detected to evaluate respiratory epithelial damage, and the sputum eosinophil cationic protein (ECP) concentration was measured to evaluate eosinophil activation in the airways. Airway responsiveness was measured before and 48 hours after the challenge.

RESULTS

The maximal % fall in FEV1 with the late asthmatic response was significantly higher after induction of allergen-induced asthma than after exercise-induced asthma, even though the maximal % fall in FEV1 with the immediate asthmatic response was similar. Airway responsiveness increased significantly at 48 hours after allergen-induced asthma, while it did not change after exercise-induced asthma. The increase in airway responsiveness was not correlated with the maximal % fall in FEV1 with the late asthmatic response, but was correlated with the degree of epithelial damage evaluated by observation of Creola bodies. The sputum ECP concentration and the percentage of sputum eosinophils increased significantly with the late asthmatic response after allergen-induced asthma, but did not change after exercise-induced asthma.

CONCLUSIONS

We conclude that less airway inflammation was provoked by exercise-induced asthma resulting in less epithelial damage and no increase of airway responsiveness in contrast to allergen-induced asthma.

Exercise- and cold-induced asthma

Exercise- and cold-induced asthma are commonly recognized respiratory disorders. The asthmatic response includes several factors contributing to airway narrowing, and thus increased airway resistance. These include airway smooth muscle contraction, mucus accumulation, and bronchial vascular congestion as well as epithelial damage and vascular leakage. The etiology for these disorders is nonantigenic. The primary stimulus is probably a combination of airway cooling and drying (leading to hypertonicity of airway lining fluid). Symptoms generally do not occur during the stimulus period (e.g., exercise) itself. This protection may in part be due to increased catecholamine levels during exercise. The early phase response, which occurs 5 to 15 min poststimulus, may be mediated through a combination of (a) direct influences, (b) vagal reflexes triggered by airway sensory receptors, or (c) responses to mediator release. Spontaneous recovery occurs within 30 min to 2 hrs. There is usually a refractory period of about 1 to 2 hrs during which responses to further stimuli are attenuated. This may be due to depletion of histamine and other mediators. As well, prostaglandin release (mediated via LTD4 which is released during exercise) inhibits further airway narrowing. A late phase response has been reported 4 to 10 hrs poststimulus in some patients. These reactions are accompanied by a second release of histamine and other mediators that cause inflammatory responses and epithelial damage. However, the exercise dependence of this response is debated.

Airway responsiveness to allergen is increased 24 hours after exercise challenge

Although exercise is one of the most ubiquitous triggers of acute bouts of asthma, the changes in airway responsiveness before and after exercise are not well defined. Specifically, the effect of the changes in airway responsiveness induced by exercise has not been studied on subsequent allergen exposure. To test whether the reactivity to allergen is altered by preceding exercise and to define possible factors determining it, we subjected 24 children with atopic asthma to the relevant allergen challenge on two occasions: one as a control without a preceding procedure and the other 24 hours after exercise challenge. Mean postallergen maximal percent falls in forced expiratory volume in 1 second from baseline (delta FEV1) of the whole group were higher after the exercise challenge compared with those of control in both early (< 1 hour) and late (3 to 10 hours) phases. The changes of postallergen maximal delta FEV1 between the control and post-exercise allergen challenges were not related to the early bronchial response to the preceding exercise challenge. Late asthmatic responses to exercise developed in six children, and the changes in both early and late phases were significantly higher in these children, compared with those without late asthmatic responses. Furthermore, the changes were well correlated with the magnitude of the late-phase response to preceding exercise in the group as a whole. It is concluded that an increased airway responsiveness to allergen occurs 24 hours after exercise in some patients with asthma. As the changes are related to a late bronchial response to exercise, late asthmatic response to exercise, when it occurs, may be associated with increased asthmatic symptoms for as long as 24 hours after exercise.

Exercise induced asthma: a clinical perspective

Exercise is a very common precipitant of asthma. Inflammation and edema are felt to be important components of the asthmatic response. Heat and water loss from the airway mucosa are most likely important in its pathogenesis, although the exact etiology remains unknown. A good history combined with proper diagnostic testing can usually determine the diagnosis, and prevention is the key to effective management. Although modified training techniques are often helpful, medications are usually needed for both prevention and treatment. While antiinflammatory agents are gaining therapeutic importance, inhaled beta-agonists remain the treatment of choice. With appropriate diagnosis and management, exercise-induced asthma should not limit participation nor performance in athletics for the great majority of the population.

Airway inflammation, bronchial reactivity and asthma

Asthma is a common disease of children the basis of which is a state of chronic immunological inflammation which causes bronchial hyperreactivity and renders the patient liable to develop widespread airways obstruction in response to a variety of stimuli. In many instances it is likely that the immunological inflammation results from ongoing antigenic stimuli with the release of chemical mediators responsible for short term bronchospasm and cytokines responsible for the ongoing inflammatory process. Other insults can apparently result in very similar immunological events in asthmatics, particularly viral infections and a similar process can be initiated in children without asthma, including those with chronic bacterial infections of the lungs. There are differences in the bronchial hyperreactivity of asthma and other diseases which suggest that in the asthmatic the mast cell is either different structurally or functionally and this renders the patient susceptible to exercise induced asthma in addition to the bronchial hyperreactivity to chemical mediators common to a number of diseases with hyperreactivity. There is good evidence of direct genetic control of atopy and the large majority of children with asthma are atopic but there is no direct genetic link between atopy and asthma and twin studies strongly suggest the existence of a 'permissive' asthma gene which will allow the disease to develop if there is an appropriate external trigger. The only drugs which have been shown to significantly reduce bronchial reactivity are the corticosteroids with a lesser effect noted for sodium cromoglycate and nedocromil. Inhaled corticosteroids can reverse the immunologic inflammatory process and reduce bronchial reactivity, sometimes to normal levels, but on stopping treatment the patient reverts back to the asthmatic state. At the present time it appears that controlled longterm inhaled corticosteroid therapy is the most rational treatment for significant perennial childhood asthma.

Reproducibility of late phase pulmonary response to exercise and its relationship to bronchial hyperreactivity in children with chronic asthma

To determine the reproducibility of the delayed response to exercise and its effect on bronchial hyperreactivity, we had 26 asthmatic children perform treadmill exercise challenge on two occasions 1 week apart. Both challenges were preceded by 2 control days and 1 histamine challenge day, and were followed by another histamine challenge day. Peak expiratory flow rate (PEFR) was measured hourly for 12 hours on each control day and for 12 hours after each exercise or histamine challenge. During the first week, five patients showed a late reaction (PEFR change > 15%) after exercise, which was present in only two of them the following week. These two patients, however, also showed a spontaneous fall > 15% of PEFR from baseline during the other control study days. A similar pattern was seen in two other patients who had a late response during the second exercise challenge but not during the first. No significant change occurred in histamine PC-20 FEV1 between before and after the exercise challenges. An apparent late asthmatic response after exercise challenge may represent a within-day fluctuation in pulmonary mechanics that develops spontaneously in children with asthma.

Late asthmatic responses after exercise challenge are reproducible

In this study the reproducibility of a late asthmatic reaction (LAR) after exercise challenge (EC) has been documented. Eighty-three hospitalized patients with asthma were challenged with exercise. The patients were examined according to a standardized protocol that comprised 8 minutes of bicycling at 90% of predicted heart rate. An LAR after EC was considered to have occurred when there was a fall in peak expiratory flow rate greater than or equal to 20% on three or more time points on the exercise day compared to corresponding clock time on a control day. According to these criteria, 11 patients (13.3%) experienced an LAR. Those patients were rechallenged 21 to 150 days after the first EC, without changing the therapy regimen of the patients, to study its reproducibility. Eight patients (73%) demonstrated a reproducible LAR after EC based on the criteria for a positive LAR. Although the LAR after EC was reproducible, the time points at which the LAR took place after the second EC differed from LARs after the first EC. Our results indicate that the LAR after EC occurs in a considerable number of patients with bronchial asthma and is quite reproducible.

Exercise response in 404 young men with asthma: no evidence for a late asthmatic reaction

As the existence of a late reaction in exercise induced asthma is controversial, peak expiratory flow (PEF) was measured for up to 13 hours after a running test in 404 consecutive young male army conscripts undergoing assessment of their asthma. In 294 subjects (73%) the immediate post-exercise fall in PEF was 10% or more; the mean (SD) fall in PEF in this group was 27% (15%). Nine patients with exercise induced asthma had a fall in PEF of 20% or more 4-13 hours after the exercise test. In these possible "late responders," however, the change in PEF 4-13 hours after exercise was similar to the change in PEF on control days before and after the exercise day, and the lowest PEF during this period was similar to the lowest measurements on the control days. These nine subjects showed pre-exercise bronchodilatation. Their pre-exercise PEF, from which the percentage fall in PEF was calculated, was 24% (9%) higher than the mean PEF level on control days. This study supports the view that what appears to be a "late asthmatic reaction" after exercise is an artefact. Spontaneous within day fluctuation in pulmonary function, pre-exercise bronchodilatation, and the fact that airflow obstruction persists after the early postexercise response may give a false impression of an exercise induced late asthmatic response in patients with labile airways.

Real and pseudo late asthmatic reactions after submaximal exercise challenge in patients with bronchial asthma. A new definition for late asthmatic responses after exercise challenge

The late asthmatic reaction after exercise challenge remains a controversial issue. In this study, 21 patients recorded peak expiratory flow rate (PEFR) on two control days without performing exercise. There was no difference between both control days when PEFR at 1 h was compared with baseline PEFR and when PEFR at 4 to 13 hours was compared with baseline PEFR. After analyzing variation coefficients of baseline PEFR on a control day and exercise day, PEFR was not allowed to differ more than 15.3 percent in the same patient when comparing exercise day and control day for the late fall in PEFR in the study. In 17 of 81 patients, a late asthmatic reaction after exercise challenge was present when PEFR fall was greater than or equal to 20 percent compared with baseline PEFR value. In eight of the 17 patients, a real late asthmatic reaction to exercise challenge was present with a PEFR fall greater than or equal to 20 percent on at least three successive time points and who had a PEFR fall greater than or equal to 20 percent compared with corresponding clocktime on a control day. The late asthmatic reaction to exercise challenge is characterized not as a nonspecific epiphenomenon, but as a fall in PEFR of greater than or equal to 20 percent compared with baseline PEFR value and with corresponding clocktime on a control day on at least three successive time points. Graphic illustration of airway responses following exercises may facilitate the detection of a late asthmatic response.

Wheezing or Breezing Through Exercise-Induced Asthma

Treatment of athletes with exercise-induced asthma (EIA) varies depending on the severity of the condition and other factors. In this article, several physicians discuss the tests they use to diagnose EIA, the medications they typically prescribe and why, as well as the importance of properly educating athletes about EIA.

Twenty years of sodium cromoglycate treatment: a short review

Sodium cromoglycate (Intal) was first synthesized from khellin, a naturally occurring plant chromone, by Roger Altounyan and his colleagues in 1965. It was introduced as a therapeutic agent in 1968 and marked a new era in the management of asthma. Numerous studies on the use of sodium cromoglycate in the treatment of asthma have since been published. Both short-term and long-term controlled studies indicate unequivocally that sodium cromoglycate is of significant clinical benefit in 60-70% of asthmatic children and adults. Clinical experience during the last 20 years has indicated that it should be the drug of first choice in the short-term treatment of asthma provoked by irritants, allergens and exercise, as well as in chronic asthma. Side effects are usually minor and sodium cromoglycate is the safest therapeutic agent in current use for the treatment of asthma.