Exercise-induced Bronchoconstriction Group Research Articles

Breathing pattern changes in response to bronchoconstriction in physically active adults

Objectives To determine whether Opto-Electronic Plethysmography (OEP) can distinguish Exercise-Induced Bronchoconstriction (EIB) breathing patterns by comparing individuals with and without EIB, and between broncho-constriction and recovery. Breathing pattern was quantified in terms of regional contribution, breathing timing, and the phase between chest sub-compartments which indicates the synchronization in movement of the different sub-compartments. Methods Individuals (n = 47) reporting no respiratory symptoms and no history of any respiratory disease or disorder were assumed to have a healthy breathing pattern. Of 38 participants reporting respiratory symptoms during exercise, and/or a previous diagnosis of asthma or EIB, 10 participants had a positive result to the Eucapnic Voluntary Hyperpnea test, defined as a fall of at least 10% in FEV1 from baseline at two consecutive time points and were classified into the EIB group. OEP data was obtained from 89 markers and an 11-camera motion capture system operating at 100 Hz as follows: pre- and post-EVH challenge, and post-inhaler in participants who experienced a bronchoconstriction, and 2) for the healthy group during tidal breathing. Results RCpRCa-Phase (upper versus lower ribcage), RCaS-Phase (lower ribcage versus shoulders), and RCpS-Phase (upper ribcage versus shoulders) differed between bronchoconstriction and rest in athletes with EIB and rest in healthy participants (p < 0.05), in all cases indicating greater asynchrony post-bronchoconstriction, and later movement of the abdominal ribcage (RCa) post-bronchoconstriction. RCpS-Phase was different (p < 0.05) between all conditions (rest, post-bronchoconstriction, and post-inhaler) in EIB. Conclusions OEP can characterize and distinguish EIB-associated breathing patterns compared to rest and individuals without EIB at rest.

Cut-off value for exercise-induced bronchoconstriction based on the features of the airway obstruction.

The current cut-off value for diagnosing exercise-induced bronchoconstriction (EIB) in adults—percent fall in FEV1 (ΔFEV1) ≥ 10% after exercise challenge test (ECT)—has low specificity and weak evidences. Therefore, this study aimed to identify the cut-off value for EIB that provides the highest diagnostic sensitivity and specificity. Participants who underwent the ECT between 2007 and 2018 were categorized according to ΔFEV1: definite EIB (ΔFEV1 ≥ 15%), borderline (10% ≤ ΔFEV1 < 15%), and normal (ΔFEV1 < 10%). Distinct characteristics of the definite EIB group were identified and explored in the borderline EIB group. A receiver operating characteristic curve was plotted to determine the optimal cut-off value. Of 128 patients, 60 were grouped as the definite EIB group, 23 as the borderline group, and 45 as the normal group. All participants were men, with a median age of 20 years (interquartile range [IQR:] 19–23 years). The definite EIB group exhibited wheezing on auscultation (P < 0.001), ΔFEV1/FVC ≥ 10% (P < 0.001), and ΔFEF25–75% ≥ 25% (P < 0.001) compared to other groups. Eight (8/23, 34.8%) patients in the borderline group had at least one of these features, but the trend was more similar to that of the normal group than the definite EIB group. A cut-off value of ΔFEV1 ≥ 13.5% had a sensitivity of 98.5% and specificity of 93.5% for EIB. Wheezing on auscultation, ΔFEV1/FVC ≥ 10%, and ΔFEF25–75% ≥ 25% after ECT may be useful for the diagnosis of EIB, particularly in individuals with a ΔFEV1 of 10–15%. For EIB, a higher cut-off value, possibly ΔFEV1 ≥ 13.5%, should be considered as the diagnostic criterion.

Differences in laryngeal movements during exercise in healthy and dyspnoeic adolescents

ObjectivesTo compare glottic and supraglottic movements in healthy adolescents and adolescents experiencing dyspnoea during strenuous exercise. MethodsUsing the continuous laryngoscopy exercise (CLE)-test laryngeal movements during exercise were analysed in healthy controls (n = 28) and compared to subjects with exercise induced bronchoconstriction (EIB) (n = 10), exercise induced laryngeal obstruction (EILO) (n = 10) and subjects experiencing exercise-induced dyspnoea without having any of these diagnoses (n = 31). Images from the video recordings were assessed regarding glottic angle, glottic area and supraglottic area using the software measuring tool EILOMEA. ResultsNo significant differences were detected between controls, the dyspnoea group without a diagnosis of EIB or EILO and the EIB group regarding glottis angle, glottis area or supraglottic area at maximum effort. All three parameters differed significantly in the EILO group compared to the other groups (p=<0.001). In the group with EILO all but one had supraglottic obstruction (corresponding to a CLE-test score ≥2). Movement of the laryngeal structures, corresponding to a CLE-test score of 1, at glottic and/or supraglottic level was seen in 26 of 35 (74%) of controls, 34 out of 41 (83%) of patients in the dyspnoea group, and in 25 of 38 (66%) of EIB-subjects. ConclusionMinor movements at both glottic and supraglottic level are equally common in healthy controls as among adolescents with exercise induced dyspnoea without EIB or EILO and adolescents with EIB. Adolescents with EILO had a statistically significant more pronounced supraglottic obstruction than the other groups.

Subjective responses to sprint interval exercise in adults with and without Exercise-induced bronchoconstriction

ABSTRACTObjective: Little is known of the subjective response to exercise that involves short “all out” bursts of effort, separated by recovery periods (sprint interval exercise (SPRINT)) among adults with exercise-induced bronchoconstriction (EIBC). The purpose of this study was to compare subjective responses to SPRINT and moderate intensity continuous exercise (MOD) among adults with EIBC, and to compare these responses between adults with EIBC and those without EIBC. Methods: Eight adults (22.3 ± 3.0 years) with EIBC, and eight adults (22.3 ± 3.0 years) without EIBC completed a SPRINT (4 × 30 second sprints separated by 4.5 minutes of active recovery) and MOD (20 minutes at 65% peak power output) session in random order. Self-reported affect, perceived breathlessness, and perceived exertion were recorded throughout exercise using validated scales. Enjoyment was assessed following exercise. Results: Differences between SPRINT and MOD were observed such that affect and perceived breathlessness were worse during the initial stages of SPRINT than MOD; however, differences disappeared by the end of exercise. Enjoyment was similar for SPRINT and MOD in the EIBC group (SPRINT: 72.9 ± 20.0 vs. MOD: 79.5 ± 20.5, p = 0.25), and between groups for SPRINT and MOD. Conclusions: Perceived breathlessness may impact affect during the early stages of exercise among those with EIBC. Post-exercise enjoyment appears to be similar between SPRINT and MOD. Future research is needed to better understand the relationship between ventilation patterns, exercise intensity, and enjoyment of exercise among those with EIBC.

What Makes a Difference in Exercise-Induced Bronchoconstriction: An 8 Year Retrospective Analysis

BackgroundExercise-induced bronchoconstriction (EIB) was recently classified into EIB alone and EIB with asthma, based on the presence of concurrent asthma.ObjectiveDifferences between EIB alone and EIB with asthma have not been fully described.MethodsWe retrospectively reviewed who visited an allergy clinic for respiratory symptoms after exercise and underwent exercise bronchial provocation testing. More than a 15% decrease of forced expiratory volume in 1 second (FEV1) from baseline to the end of a 6 min free-running challenge test was interpreted as positive EIB.ResultsEIB was observed in 66.9% of the study subjects (89/133). EIB-positive subjects showed higher positivity to methacholine provocation testing (61.4% vs. 18.9%, p<0.001) compared with EIB-negative subjects. In addition, sputum eosinophilia was more frequently observed in EIB-positive subjects than in EIB-negative subjects (56% vs. 23.5%, p = 0.037). The temperature and relative humidity on exercise test day were significantly related with the EIB-positive rate. Positive EIB status was correlated with both temperature (p = 0.001) and relative humidity (p = 0.038) in the methacholine-negative EIB group while such a correlation was not observed in the methacholine-positive EIB group. In the methacholine-positive EIB group the time to reach a 15% decrease in FEV1 during exercise was significantly shorter than that in the methacholine-negative EIB group (3.2±0.7 min vs. 8.6±1.6 min, p = 0.004).ConclusionsEIB alone may be a distinct clinical entity from EIB with asthma. Conditions such as temperature and humidity should be considered when performing exercise tests, especially in subjects with EIB alone.

Fractional exhaled nitric oxide (FeNO) may predict exercise-induced bronchoconstriction (EIB) in schoolchildren with atopic asthma

BackgroundThere is a need for the performance of exercise-induced bronchoconstriction (EIB) tests in the monitoring of childhood asthma control. We aimed to evaluate whether in children with atopic asthma, EIB can be predicted by one or more of the following parameters or by their combination: fractional exhaled nitric-oxide (FeNO), allergy profile, asthma treatment, total IgE serum concentration and eosinophil blood count (EBC). MethodsIt was a retrospective, cross-sectional study. We evaluated data from medical documentation of children with atopic asthma who had performed standardized spirometric exercise challenge test. ResultsOne hundred and twenty six patients with atopic asthma, aged 5–18, were included in the analysis. There were two groups of patients: the EIB group (n=54) and the no-EIB group (n=72). The median FeNO level prior to exercise in the EIB group was 27.6 vs. 16.3ppb in the no-EIB group (p=0.002). FeNO level higher than 16ppb had the highest diagnostic value to confirm EIB. When using the FeNO level of >16ppb, the sensitivity, specificity, negative predictive and positive predictive values for EIB were 83%, 46.9%, 74.2%, and 60%, respectively. In the EIB group, the degree of FeNO elevation did correlate positively with the absolute fall in FEV1 (p=0.002; r=0.45). The FeNO value of >16ppb, EBC value of >350cell/mm3 and allergy to house dust mites presented the highest odds ratios of EIB. However, the FeNO value of >16ppb was the only independent odds ratio of EIB. ConclusionsElevated FeNO level increased the odds of EIB in asthmatic schoolchildren, independently of other asthma severity markers and the intensity of anti-asthma therapy. It seems likely that FeNO measurement may act as a screening tool and help to prevent under-diagnosis and under-treatment of exercise-induced bronchoconstriction in schoolchildren with atopic asthma.

8-Isoprostane in Exhaled Breath Condensate and Exercise-Induced Bronchoconstriction in Asthmatic Children and Adolescents

Exercise-induced bronchoconstriction (EIB) in the asthmatic child is associated with persistent airway inflammation and poor disease control. EIB could arise partly from airway oxidative stress. Exhaled breath condensate (EBC) levels of 8-isoprostane (IsoP), which is a known marker of oxidative stress, might therefore be helpful for monitoring asthma noninvasively. We recruited 46 asthmatic children and adolescents 6 to 17 years of age (29 boys), all of whom underwent lung function testing, measurement of the fractional concentration of exhaled nitric oxide (FENO), and collection of EBCs for 8-IsoP measurement before and after exercise challenge. FENO was measured before exercise and 5 min and 20 min after exercise. Spirometry was repeated 1, 5, 10, 15, and 20 min after exercise. Baseline 8-IsoP levels (but not baseline FENO levels) correlated with the fall in FEV(1) 5 min after exercise (r = - 0.47; p = 0.002). 8-IsoP levels measured after exercise remained unchanged from baseline levels; conversely, FENO levels decreased in parallel with the decline in FEV(1) at 5 min (r = 0.44; p = 0.002). The mean baseline 8-IsoP concentrations were higher in patients with EIB (n = 12) than in those without EIB (n = 34; 44.9 pg/mL [95% confidence interval (CI), 38.3 to 51.5] vs 32.3 pg/mL [95% CI, 27.6 to 37.0], respectively; p < 0.01). No difference was found in the mean baseline FENO between groups (with EIB group: 38.7 ppb; 95% CI, 24.5 to 61.1; without EIB group: 29.1 ppb; 95% CI, 22.0 to 38.4). Increased 8-IsoP concentrations in EBC samples of asthmatic children and adolescents with EIB suggest a role for oxidative stress in bronchial hyperreactivity.

Exercise-induced asthma in asthmatic children. Predisposing factors

Exercise-induced bronchoconstriction (EIB) has a high prevalence in children with asthma, and this is a common problem, even in case of controlled asthma, because of the high levels of physical activity in the childhood. The aim of our study was to identify factors associated with the development of EIB in children with controlled asthma. We studied children evaluated for asthma. A personal and familiar history was collected from each patient to estimate asthma severity, precipitating factors, exercise ability, immunotherapy treatment and atopic familiar disorders. Skin prick tests for inhalant allergens, pulmonary function tests (PFTs) and exercise challenge test (ECT) measurements were realized in every patient. We used the Chi Squared test to compare qualitative variables, the Student's-t test for quantitative variables and a logistic regression analysis to estimate the independent effect of the variables. We evaluated 132 asthmatic patients. Eighty-two, 6 to 14 years old (average 110 +/- 36.9 months), were included in the study. Forty one have coughing or wheezing with exercise at least three months ago, in addition to a positive ECT; 9 of these children had solitary EIB (group A), and 32 (group B) had controlled chronic asthma, 27 intermittent and 5 moderately persistent. Forty one controlled asthmatic children, 39 intermittent, 1 mildly persistent and 1 moderately persistent (group C) had a good tolerance for exercise with a negative ECT. No differences were found in familiar history, asthma severity or evolution time in B vs C group. We found that 35 patients (42,68 %) patients were sensitized to indoor allergens: 24 (58,53 %) were patients suffering EIB and 11 (26,8 %) allowed to group C. Precipitating factors of asthma were in group B: respiratory infections in 19 cases, pollen in 20 and in 10 indoor allergens exposure. In group C: 14 patients had asthmatic symptoms with viral respiratory infections, 32 with pollen and 2 with indoor allergens exposure. A patient from group A had allergy rhinitis after exposure to cats. Allergy to indoor allergens demonstrated an direct association to EIB suffering (p = 0,026). Twenty six patients with allergic asthma followed pollen immunotherapy treatment, 7 of group B (33,3 %) and 19 (59,3 %) of group C. This treatment was inversely associated with EIB suffering (p = 0,048). A logistic regression analysis confirmed the independence of both variables as predisposing and protecting factors in EIB suffering. Allergy to indoor allergens might be considered a risk factor for EIB. Immunotherapy treatment could be a protective factor against the development of EIB in children with allergic asthma.

Changes in Serum Eosinophil Cationic Protein Levels after Exercise Challenge in Asthmatic Children

The aim of the present study was to assess the relationship between serum eosinophil cationic protein levels and the severity of exercise-induced bronchoconstriction in asthmatic children. The 48 asthmatic children were divided into exercise-induced bronchoconstriction group and non-exercise-induced bronchoconstriction group. In the exercise-induced bronchoconstriction group, the post-exercise serum eosinophil cationic protein levels were significantly increased as compared with the pre-exercise serum eosinophil cationic protein levels. These results suggested that eosinophil cationic protein may serve as a possible contributor to the pathophysiology of exercise-induced bronchoconstriction in asthmatic children.

Exhaled Nitric Oxide and Airway Caliber during Exercise-Induced Bronchoconstriction

Data on the relationship between exercise-induced bronchoconstriction (EIB) and exhaled nitric oxide (NO) in adult patients with asthma are controversial. It is unclear whether endogenous NO may act as either a protective or stimulatory factor in the airway response to exercise or whether changes in exhaled NO simply reflect acute narrowing of the airway. The aim of this study was to assess the changes in the fraction of exhaled nitric oxide (FE(NO)) before and after exercise challenge in patients with asthma and to analyze the relationship between FE(NO) and airway obstruction. Twenty-five non-smoking, steroid-naïve, atopic, adult patients with mild persistent asthma and 12 non-smoking, nonatopic, healthy subjects (control group) performed an exercise challenge on a cycloergometer, with monitored ventilation. FEV1 and FE(NO) were measured at baseline and 1, 5, 10, 15 and 20 minutes after the exercise challenge. Eleven of the asthmatic patients had exercise-induced bronchoconstriction (EIB group) and the remaining 14 did not (non-EIB group). Baseline FE(NO) was higher in the EIB and non-EIB asthmatic groups than in the control group. In the EIB group, FE(NO) was significantly lower 5, 10 and 15 minutes after exercise, and the changes in FE(NO) correlated with variation in FEV1 10 and 15 min after exercise. A significant correlation between baseline FE(NO) and maximal post-exercise decrease in FEV1 was found in asthmatic patients (EIB group). In conclusion, exhaled nitric oxide levels transiently decrease during exercise-induced bronchoconstriction in adult patients with asthma. Baseline FE(NO) might predict the airway obstruction resulting after exercise.

Undiagnosed Exercise-Induced Bronchoconstriction in Ski-Mountaineers

Because the practise conditions put the ski-mountaineering athletes potentially at risk for exercise-induced bronchoconstriction (EIB), this study was conducted to estimate the prevalence of EIB in this population. Thirty-one highly-trained ski-mountaineers with racing experience participating in the race were evaluated. EIB was determined after a European race at high altitude and frigid conditions. Pre-race investigations included pulmonary function measurements and a questionnaire enquiring about i) training habits, ii) respiratory history during training and/or competition. Pulmonary function was also tested after the race. None of the athletes reported a basal airway obstruction. Two groups were determined after post-race airway response: i) EIB (+) group exhibiting a fall in FEV (1) > or = 10 % (n = 15) and ii) EIB (-) without fall in FEV (1) or fall < 10 % (n = 16). Neither training habits nor baseline lung function were associated with the post-race airway response. Six of the 31 ski-mountaineers had a previous physician-made diagnosis of asthma and/or EIB, nevertheless 23 of our athletes complained about at least one characteristic symptom of asthma during practise. Four of our 15 EIB (+) had a previous physician-made diagnosis of asthma/EIB indicating that 73 % of EIB (+) athletes were undiagnosed for EIB. The proportion of allergic athletes was not significantly different between EIB (+) and EIB (-). This study showed that approximatively half of highly-trained ski-mountaineers with racing experience can develop EIB after a race and that 73 % of them are unaware of the problem.

Exhaled breath condensate cysteinyl leukotrienes are increased in children with exercise-induced bronchoconstriction

It is recognized that airway inflammation has a central role in the pathogenesis of asthma, but how it relates to exercise-induced bronchoconstriction (EIB) is not completely understood. The aim of our study was to investigate the relationship between EIB and baseline concentrations of cysteinyl leukotrienes (Cys-LTs) and other inflammatory markers in exhaled breath condensate (EBC). EBC was collected, and the fraction of exhaled nitric oxide (FE NO ) was measured in a group of 19 asthmatic children, after which they performed a treadmill exercise test. Fourteen healthy children were enrolled as control subjects. The asthmatic children were divided into the EIB group (decrease in FEV 1 , > or =12%) and the non-EIB group. The EBC was analyzed for the presence of Cys-LTs, leukotriene B 4 , and ammonia. Asthmatic patients with EIB (mean FEV 1 decrease, 23% +/- 3%) had higher Cys-LT concentrations than either asthmatic patients without EIB or control subjects (42.2 pg/mL [median] vs 11.7 pg/mL and 5.8 pg/mL; P < .05 and P < .001, respectively). Ammonia concentrations were lower in both the EIB and non-EIB groups than in control subjects (253.2 microM and 334.6 microM vs 798.4 microM; P < .01 and P < .05, respectively). No difference in EBC leukotriene B 4 levels was found among the 3 groups. Both asthmatic groups had higher FE NO levels than control subjects ( P < .001). EBC Cys-LT ( P < .01; r = 0.7) and FE NO ( P < .05; r = 0.5) values both correlated significantly with the postexercise FEV 1 decrease. this study shows that EBC Cys-LT values are higher in asthmatic children with EIB and correlate with the decrease in FEV 1 after exercise. These findings suggest that the pathways of both Cys-LT and nitric oxide are involved in the pathogenesis of EIB.

Exhaled Nitric Oxide as a Predictor of Exercise-Induced Bronchoconstriction

Exercise-induced bronchoconstriction (EIB) is present in 40 to 90% of patients with asthma. Exhaled NO (eNO) levels have been correlated with bronchial hyperresponsiveness to methacholine, and have correlated with the degree of decrease in FEV(1) with exercise. The purpose of our study was to examine whether eNO measurements prior to or after exercise could be used as a surrogate marker of exertional bronchoconstriction in a population referred specifically for the evaluation of EIB. We studied 50 consecutive subjects without a history of asthma who were referred for the clinical evaluation of EIB. eNO levels were measured prior to exercise challenge and every 5 min for a total of 30 min after exercise. Forced expiratory flows were measured prior to and serially after exercise challenge. Seven subjects had a decrease in FEV(1) of > or = 15% with exercise. The mean eNO level prior to exercise was 41 parts per billion (ppb) [median +/- SD, 23 +/- 42.2 ppb] in the EIB group and 25.6 ppb (median, 19.95 +/- 18.47 ppb) in the group without EIB. A receiver operator characteristic curve yielded a value of 0.636. When using an eNO level of < 12 ppb, the sensitivity, specificity, negative predictive value, and positive predictive value for EIB were 1.0, 0.31, 0.19, and 1.0, respectively; therefore, no one with a baseline eNO of < 12 ppb demonstrated EIB. No subjects with very low pre-exercise eNO levels (< 12 ppb) demonstrated bronchial hyperresponsiveness to exercise. eNO measurement may obviate the need for bronchoprovocation testing in patients who complain of exertional dyspnea.

Exhaled nitric oxide decreases during exercise-induced bronchoconstriction in children with asthma.

Nitric oxide (NO) produced in the airways can be either detrimental or protective to the host. To investigate the role of NO in the pathogenesis of exercise-induced bronchoconstriction (EIB), we measured exhaled NO (ENO) after exercise challenge in 39 asthmatic and six normal children. FEV(1) and ENO were measured before and at 0, 5, 10, and 15 min after exercise performed on a treadmill for 6 min. EIB was defined as a decrease in FEV(1) of more than 15% after the exercise. Normal children (control group) did not have EIB. Twenty-one patients with asthma had EIB (EIB group) whereas the remaining 18 patients did not (non-EIB group). The baseline ENO value was significantly higher in the asthmatic children than in the normal children, and there was a positive correlation between the maximal percent decrease in FEV(1) and the baseline ENO value (r = 0.501, p = 0.012). At the end of the exercise, ENO had decreased in all the subjects. In the non-EIB and control groups, ENO rebounded to above the baseline at 5 min after the exercise and thereafter. In contrast, ENO remained at a decreased level in the EIB group. The change in ENO did not correlate with the change in minute ventilation, and beta-agonist inhalation at the peak of EIB that accelerated the recovery of FEV(1) did not affect the depressed level of ENO, demonstrating that the reduction of ENO is not a simple consequence of increased ventilation nor airway obstruction. Among the EIB group, steroid-treated patients showed sooner recovery in ENO after the exercise than steroid-naive patients. Our study suggests that NO production in response to exercise may be impaired in patients with EIB, and that ENO represents not only airway inflammation but also a protective function of NO in EIB.

Exhaled nitric oxide and exercise-induced bronchoconstriction in asthmatic children.

It is known that exhaled nitric oxide (ENO) is increased in asthmatic individuals, probably as an expression of airway inflammation, but no studies have been reported of ENO and exercise-induced bronchoconstriction (EIB). We assessed the effect of a treadmill exercise challenge on ENO concentration in 24 asthmatic children aged 11.2 +/- 0.4 yr (mean +/- SEM). According to the presence or absence of EIB, the children were divided into an EIB group (n = 10) and a non-EIB group (n = 14). ENO was measured with a single-breath reservoir technique. FEV(1), ENO, and heart rate were measured at baseline and 1, 6, 12, and 18 min after the end of exercise. We also measured ENO in 18 healthy control children aged 10.8 +/- 0.6 yr, of whom nine underwent an exercise challenge identical to that of the asthmatic children. After the exercise test, the mean decrease in FEV(1) was 34% in the EIB group and 5% in the non-EIB group. The EIB group had higher baseline ENO values (12.3 +/- 1.6 ppb) than the healthy children (6.1 +/- 0.2 ppb) (p < 0.01). The time course of ENO was similar in the EIB, non-EIB, and control groups, with no significant changes after exercise (p = NS). In the overall group of asthmatic children there was a significant correlation (r = 0.61, p < 0.01) between baseline (preexercise) ENO and magnitude of the maximal decrease in FEV(1) after exercise. In conclusion, our study shows that ENO levels do not change during acute airway obstruction induced by exercise challenge in asthmatic children. In addition, baseline ENO values correlate with the magnitude of postexercise bronchoconstriction, suggesting that NO may be a predictor of airway hyperresponsiveness to exercise.

Correlation of Exercise-Induced Bronchoconstriction to PC20 and Maximal AirwayNarrowing on the Dose-Response Curve to Methacholine

Background: Exercise is one of the most common precipitants of acute asthma encountered in clinical practice. The development of airflow limitation that occurs several minutes after vigorous exercise, i. g. exercise-induced bronchoconstriction(EIB), has been shown to be closely correlated with the nonspecific bronchial hyperresponsiveness, which is the hallmark of bronchial asthma. All previous reports that assessed the correlation of EIB to nonspecific bronchial hyperresponsiveness have focused on airway sensitivity() to inhaled bronchoconstrictor such as methacholine or histamine. However, maximal airway narrowing(MAN), reflecting the extent to which the airways can narrow, when being exposed to high dose of inhaled stimuli, has not been studied in relation to the degree of EIB. Methods: Fifty-six children with mild asthma(41 boys and 15 girls), aged 6 to 15 years(meanSD, years) completed this study. Subjects attended the laboratory on two consecutive days. Each subject performed the high-dose methacholine inhalation test at 4 p.m. on the first day. The dose-response curves were characterized by their position() and MAN, which was defined as maximal response plateau(MRP: when two or three data points of the highest concentrations fell within a 5% response range) or the last of the data points(when a plateau could not be measured). On the next day, exercise challenge, free running outdoors for ten minutes, was performed at 9 a.m.. was measured at graduated intervals, 3 to 10 minutes apart, until 60 minutes after exercise. Response(the maximal from the pre-exercise value) was classified arbitrarily into three groups; no response((-) EIB: EIB:10%EIB:>20%). Results: 1) When geometric mean of the three groups were compared, of (+) EIB group was significantly lower than that of (-)EIB group. 2) There was a close correlation between and the severity of EIB in the whole group(r=-0.568, p) to methacholine is correlated well with the severity of EIB. The results suggest that the two main components of airway hyperresponsiveness may be equally important determinants of exercise reactivity, although the mechanism may be different from each other. The present study also provides further evidence that EIB is a manifestation of the increased airway reactivity characteristic of bronchial asthma.

Role of Alpha-Adrenergic Receptors in Exercise-Induced Bronchoconstriction

The role of alpha-adrenergic receptors in exercise-induced bronchoconstriction (EIB) was studied. 9 asthmatic patients with a marked degree of EIB (group I) and 6 asthmatic patients with no or a less severe EIB (group II) were investigated and compared with 8 healthy control persons. Pulse rate, airway resistance and end-expiratory thoracic gas volume were measured at rest and immediately and 15 min after exercise. Group I subjects showed a significant inhibition of EIB after alpha-adrenergic blockade with phentolamine (10 mg as aerosol) and after cholinergic blockade with an atropine-ester (60 mg as aerosol). In 7 of 9 patients who had received phentolamine, and in 3 of 6 patients who had received atropine-ester, the EIB was completely suppressed. In group II the administration of propranolol (40 mg orally) produced a significant increase in EIB. The effect of propranolol could be inhibited by the addition of alpha-adrenergic blockade with phentolamine (10 mg as aerosol). The control subjects had no measurable EIB, even after the administration of propranolol (40 mg orally). It is concluded that, in addition to the vagal system, an activated alpha-adrenergic system is involved in the phenomenon of EIB.