Exercise-induced bronchoconstriction, allergy and sports in children

Exercise-induced bronchoconstriction (EIB) is characterized by the narrowing of airways during or after physical activity, leading to symptoms such as wheezing, coughing, and shortness of breath. Distinguishing between EIB and exercise-induced asthma (EIA) is essential, given their divergent therapeutic and prognostic considerations. EIB has been increasingly recognized as a significant concern in pediatric athletes. Moreover, studies indicate a noteworthy prevalence of EIB in children with atopic predispositions, unveiling a potential link between allergic sensitivities and exercise-induced respiratory symptoms, underpinned by an inflammatory reaction caused by mechanical, environmental, and genetic factors. Holistic management of EIB in children necessitates a correct diagnosis and a combination of pharmacological and non-pharmacological interventions. This review delves into the latest evidence concerning EIB in the pediatric population, exploring its associations with atopy and sports, and emphasizing the appropriate diagnostic and therapeutic approaches by highlighting various clinical scenarios.

Exercise-Induced Dyspnea in Collegiate Athletes: Are We Missing the Diagnosis?

OBJECTIVES

Exercise-induced dyspnea (EID) can disrupt an athlete's participation and performance in their given sport. Differential diagnosis of EID is often completed using subjective report and may be inaccurate, therefore increasing the frustration and stress of the athlete. This nonexperimental research study was used to determine prevalence of EID and related respiratory symptoms in athletes at a small, Division I university.

METHODS

An anonymous survey was provided to athletes at Murray State University as they registered for participation in sports for the 2020-2021 school year. Data from this survey was analyzed as to reported physician-given diagnosis of a respiratory disorder as well as reported symptoms of EID.

RESULTS

Results showed that athletes with a physician-given diagnosis often did not report symptoms or responses to medications that support that diagnosis. Additionally, athletes frequently reported symptoms of EID without a formal diagnosis of a respiratory disorder.

CONCLUSIONS

These findings provide preliminary insight and pilot data that may be used to understand the prevalence of EID in collegiate athletes and the need for improved methods of diagnosis for etiologies of EID.

Diagnostic work-up of exercise-induced laryngeal obstruction

PURPOSE

Exercise-induced laryngeal obstruction (EILO) is suspected when dyspnea associated with upper airway symptoms is triggered by exercise. This condition affects mainly adolescent athletes. Visualization of the obstruction, while the patient is experiencing the symptoms during continuous laryngoscopy during exercise (CLE-test) is the gold standard for diagnosing EILO. Our study aims to evaluate the prevalence of EILO in a population presenting exercise-induced inspiratory symptoms (EIIS) or uncontrolled asthma with exertional symptoms. The second objective was to evaluate the diagnostic strength of laryngology consultation (LC) and pulmonary function tests (PFTs).

METHODS

All patients referred to our center for EIIS or uncontrolled asthma with exertional symptoms were included. EILO diagnosis was made if Maat score was > 2 for patients with CLE-test or if there were inspiratory anomalies on PFTs and LC. The sensitivity and specificity of LC and PFTs as diagnostic tools were calculated considering CLE-test as the gold standard.

RESULTS

Sixty two patients were referred to our center for EIIS or uncontrolled asthma with exertional symptoms. EILO was diagnosed in 28 patients (56%) with associated asthma in 9 patients (18%). The sensibility and specificity of LC for supraglottic anomalies were 75% and 60%, respectively. The sensibility and specificity of PFTs were 61% and 89%, respectively.

CONCLUSIONS

There was a high prevalence of EILO among patients with EIIS and uncontrolled asthma. Some clinical characteristics might guide the diagnosis. Nevertheless, CLE-test remained the gold standard for EILO diagnosis and identification of the dysfunctional upper airway site to provide specific management.

Predictors of exercise-induced bronchoconstriction in subjects with mild asthma

Background

Physical effort is capable of triggering airway obstruction in asthmatics, the so-called exercise-induced bronchoconstriction in asthma (EIBa). This study was performed in subjects with mild persistent asthma, aiming to find predictors for developing EIBa.

Methods

In 20 subjects with mild asthma, measurements of baseline functional respiratory parameters and airways responsiveness by a methacholine challenge were obtained on the first day. A maximal, symptom-limited incremental cardiopulmonary exercise test (CPExT) was performed the day after, with subsequent, repeated maneuvers of maximal full forced expiration to monitor the FEV₁ change at 1,3,5,7,10 and 15 min after the end of the exercise.

Results

19 subjects completed the two-days protocol. No functional parameters both at rest and during effort were useful to predict EIBa after stopping exercise. In asthmatics with EIBa, mean Inspiratory Capacity (IC) did not increase with increasing ventilatory requirements during CPExT because 6 of them (50%) displayed dynamic pulmonary hyperinflation (DH), as documented by their progressive increase of end-expiratory lung volume. This subgroup, showing earlier post-exercise FEV₁ fall, had significantly lower forced mean expiratory flow between 25% and 75% of forced vital capacity (FEF_25-75%) at rest (p < 0.05) and higher airways responsiveness, expressed as PD₂₀FEV₁ (p < 0.05) as compared with other asthmatics with EIBa.

Conclusions

No functional respiratory parameters seem to predict EIBa in mild asthmatics. However, in those with EIBa, a subgroup developed DH during exercise, and this was associated with a baseline reduced forced expiratory flow rates at lower lung volumes and higher airway hyperresponsiveness, suggesting a prominent small airways impairment.

Short- and long-term effects of fluticasone furate/vilaterol in exercising asthmatic adolescents: a randomized and open label trial

PURPOSE

Relvar® (Fluticasone furoate (FF)/Vilanterol (VI)) is a once-daily inhaler with bronchodilator effect lasting 24 hours. Our aim was to investigate the short- and long-term effects of FF/VI on exercise-induced asthma (EIA) in adolescents.

METHODS

Ninety-three adolescent asthmatics aged 12-18 years were referred for evaluation of EIA. Following a positive exercise challenge test (ECT), 22/44 were allocated to a single administration of salbutamol (400 μg) and 22/44 to FF/VI (92/22 μg) in a double-blind method. Thirty-five subjects were reassessed by repeat ECT 30-60 days of FF/VI.

RESULTS

Median FEV1 change post-ECT at baseline was -22.8% predicted (IQR -26.1 and -18.0) for salbutamol and -21.0 (IQR -30.7 and -16.8) for FF/VI. Following bronchodilator, FEV1 improved similarly in both groups. Repeat ECT following 30-60 days of FF/VI resulted in negative exercise challenge test in 33/35 subjects; the median decrease in FEV1 of these 35 subjects was 22.6% predicted (IQR 29-18) before, and 4.6% predicted (IQR 8.7-2.5) after 30-60 days of FF/VI treatment; p<0.0001).

CONCLUSIONS

FF/VI is effective in reversing EIA after 15 minutes in adolescents and in protecting EIA after 30-60 days in adolescents. Larger studies are needed to assess the effect of FF/VI on EIA.

Exercise-induced laryngeal obstruction: From clinical examination to continuous laryngoscopy during exercise

The diagnosis of exercise-induced laryngeal obstruction (EILO) should be suspected when exercise triggers inspiratory stridor. EILO is common in adolescent populations and has a significant impact on sports. Identification of laryngeal obstruction during continuous laryngoscopy during exercise (CLE) is the gold standard diagnostic tool for this disorder, which is not widely known in France. The challenge faced by otolaryngologists is to identify, among patients referred by pulmonologists or sports physicians, those with exercise-induced inspiratory symptoms or poorly controlled exercise-induced asthma, in whom a diagnosis of EILO is strongly suspected. Laryngoscopy at rest may reveal a laryngeal, glottic or supraglottic abnormality predictive of obstruction at increased inspiratory airflow. When pulmonary function tests are normal or in the case of failure of treatment of exercise-induced asthma, the otolaryngologist must complete the examination by a CLE test to confirm the diagnosis of EILO and identify the site of obstruction. This examination is well tolerated, minimally invasive and allows identification of the site of airflow obstruction, allowing specific conservative or surgical treatment. This technical note describes in detail clinical examination and CLE testing in patients with suspected EILO.

[Diagnostic performance of the physical activity related question of the GINA questionnaire to detect exercise-induced bronchoconstriction in asthma]

INTRODUCTION

The aim of the study was to evaluate the diagnostic performance of the item concerning physical activity of the Global Initiative for Asthma (GINA) asthma control questionnaire for detection of exercise-induced bronchoconstriction (EIB) in children and adolescents.

MATERIAL AND METHODS

We divided participants (aged 6 to 18 years) with a diagnosis of asthma into two groups according to the GINA severity classification: mild/moderate asthma (MMA) and severe therapy-resistant asthma (STRA). We collected anthropometric, clinical and functional data (spirometry) and performed an EIB test. We used item 4 of the GINA questionnaire regarding exercise-induced symptoms to assess the diagnostic power of this instrument.

RESULTS

We included 40 patients (17 with MMA and 23 with STRA) with a mean age of 11.3 years and a mean FEV₁z-score of -0.33, of who 13 (32.5%) were classified as having uncontrolled asthma. Of the patients with uncontrolled asthma, 7 (53.8%) exhibited a decrease in the FEV₁ after the EIB test. We found a higher frequency of EIB in participants with FEV₁ z-score values of less than -1.0 compared to those with a z-score of -1.0 or greater (p = 0.05). There were no significant differences in the frequency of EIB based on disease severity and control. We also found no association of item 4 (GINA) with EIB. The area under the ROC curve demonstrated that the discriminative power of the GINA questionnaire for the detection of EIB is inadequate (p = 0.41), with sensitivity of 42.1% and specificity of 57.1%.

CONCLUSIONS

The physical activity related question of GINA has insufficient diagnostic power to detect EIB in children and adolescents with asthma.

Oil supplementation with a special combination of n-3 and n-6 long-chain polyunsaturated fatty acids does not protect for exercise induced asthma: a double-blind placebo-controlled trial

BACKGROUND

Many patients suffering from exercise-induced asthma (EIA) have normal lung function at rest and show symptoms and a decline in FEV₁ when they do sports or during exercise-challenge. It has been described that long-chain polyunsaturated fatty acids (LCPUFA) could exert a protective effect on EIA.

METHODS

In this study the protective effect of supplementation with a special combination of n-3 and n-6 LCPUFA (sc-LCPUFA) (total 1.19 g/ day) were investigated in an EIA cold air provocation model.

PRIMARY OUTCOME MEASURE

Decrease in FEV₁ after exercise challenge and secondary outcome measure: anti-inflammatory effects monitored by exhaled NO (eNO) before and after sc-LCPUFA supplementation versus placebo.

RESULTS

Ninety-nine patients with exercise-induced symptoms aged 10 to 45 were screened by a standardized exercise challenge in a cold air chamber at 4 °C. Seventy-three patients fulfilled the inclusion criteria of a FEV₁ decrease > 15% and were treated double-blind placebo-controlled for 4 weeks either with sc-LCPUFA or placebo. Thirty-two patients in each group completed the study. Mean FEV₁ decrease after cold air exercise challenge and eNO were unchanged after 4 weeks sc-LCPUFA supplementation.

CONCLUSION

Supplementation with sc-LCPUFA at a dose of 1.19 g/d did not have any broncho-protective and anti-inflammatory effects on EIA.

TRIAL REGISTRATION

Clinical trial registration number: NCT02410096. Registered 7 February 2015 at Clinicaltrial.gov.

Many continuous variables should be analyzed using the relative scale: a case study of β2-agonists for preventing exercise-induced bronchoconstriction

BACKGROUND

The relative scale adjusts for baseline variability and therefore may lead to findings that can be generalized more widely. It is routinely used for the analysis of binary outcomes but only rarely for continuous outcomes. Our objective was to compare relative vs absolute scale pooled outcomes using data from a recently published Cochrane systematic review that reported only absolute effects of inhaled β₂-agonists on exercise-induced decline in forced-expiratory volumes in 1 s (FEV₁).

METHODS

From the Cochrane review, we selected placebo-controlled cross-over studies that reported individual participant data (IPD). Reversal in FEV₁ decline after exercise was modeled as a mean uniform percentage point (pp) change (absolute effect) or average percent change (relative effect) using either intercept-only or slope-only, respectively, linear mixed-effect models. We also calculated the pooled relative effect estimates using standard random-effects, inverse-variance-weighting meta-analysis using study-level mean effects.

RESULTS

Fourteen studies with 187 participants were identified for the IPD analysis. On the absolute scale, β₂-agonists decreased the exercise-induced FEV₁ decline by 28 pp., and on the relative scale, they decreased the FEV₁ decline by 90%. The fit of the statistical model was significantly better with the relative 90% estimate compared with the absolute 28 pp. estimate. Furthermore, the median residuals (5.8 vs. 10.8 pp) were substantially smaller in the relative effect model than in the absolute effect model. Using standard study-level meta-analysis of the same 14 studies, β₂-agonists reduced exercise-induced FEV₁ decline on the relative scale by a similar amount: 83% or 90%, depending on the method of calculating the relative effect.

CONCLUSIONS

Compared with the absolute scale, the relative scale captures more effectively the variation in the effects of β₂-agonists on exercise-induced FEV₁-declines. The absolute scale has been used in the analysis of FEV₁ changes and may have led to sub-optimal statistical analysis in some cases. The choice between the absolute and relative scale should be determined based on biological reasoning and empirical testing to identify the scale that leads to lower heterogeneity.

Update in Pediatric Asthma: Selected Issues

Asthma is a complex condition that affects 14% of the world's children and the approach to management includes both pharmacologic as well as non-pharmacologic strategies including attention to complex socioeconomic status phenomena. After an historical consideration of asthma, allergic and immunologic aspects of asthma in children and adolescents are presented. Concepts of socioeconomic aspects of asthma are considered along with environmental features and complications of asthma disparities. Also reviewed are links of asthma with mental health disorders, sleep disturbances and other comorbidities. A stepwise approach to asthma management is discussed that includes pharmacologic and non-pharmacologic strategies in the pediatric population. The role of immunotherapy and use of various immunomodulators are considered as well.

The Visual Analog Scale detects exercise-induced bronchoconstriction in children with asthma

Objective: Exercise-induced bronchoconstriction (EIB) is a specific morbidity of childhood asthma and an important sign of uncontrolled asthma. The occurrence of EIB is insufficiently identified by the Childhood Asthma Control Test (C-ACT) and Asthma Control Test (ACT). This study aimed to (1) evaluate the Visual Analog Scale (VAS) for dyspnea as a tool to detect EIB in asthmatic children and (2) assess the value of combining (C-)ACT outcomes with VAS scores. Methods: We measured EIB in 75 asthmatic children (mean age 10.8 years) with a standardized exercise challenge test (ECT) performed in cold and dry air. Children and parents reported VAS dyspnea scores before and after the ECT. Asthma control was assessed by the (C-)ACT. Results: Changes in VAS scores (ΔVAS) of children and parents correlated moderately with fall in forced expiratory volume in 1 second (FEV₁), respectively r_s=0.57 (p < .001) and r_s=0.58 (p < .001). At a ΔVAS cutoff value of ≥3 in children, sensitivity and specificity for EIB were 80% and 79% (AUC 0.82). Out of 38 children diagnosed with EIB, 37 had a (C-)ACT score of ≤19 and/or a ΔVAS of ≥3, corresponding with a sensitivity of 97% and a negative predictive value of 96%. Conclusion: This study shows that the VAS could be an effective additional tool for diagnosing EIB in children. A reported difference in VAS scores of ≥3 after a standardized ECT combined with low (C-)ACT scores was highly effective in detecting and excluding EIB.

Cough in exercise and athletes

In the general population, particularly in individuals with asthma, cough is a common symptom, often reported after exertion, although regular exercise may be associated with a reduction in the prevalence of cough. In athletes, exercise-induced cough is also a particularly frequent symptom. The main etiologies of cough in athletes are somewhat similar to non-athletes, including asthma/airway hyperresponsiveness, upper airways disorders such as allergic or non-allergic rhinitis, and exercise-induced laryngeal obstruction, although these conditions are more frequently observed in athletes. In these last, this symptom can also be related to the high ventilation and heat exchange experienced during exercise, particularly during exposure to cold/dry air or pollutants. However, gastroesophageal reflux, a common cause of cough in the general population, despite being highly prevalent in athletes, has not been reported as a main cause of cough in athletes. Cough may impair quality of life, sleep and exercise performance in the general population and probably also in athletes, although there are few data on this. The causes of cough should be documented through a systematic evaluation, the treatment adapted according to identified or most probable cough etiology and pattern of presentation, while respecting sports anti-doping regulations. More research is needed on exercise-induced persistent cough in the athlete to determine its pathophysiology, optimal management and consequences.

Exhaled NO as a predictor of exercise-induced asthma in cold air

PURPOSE

Physical activity is an important part of life, and exercise-induced asthma (EIA) can reduce the quality of life. A standardized exercise challenge is needed to diagnose EIA, but this is a time consuming, effortful and expensive method. Exhaled nitric oxide (eNO) as a marker of eosinophil inflammation is determined rapidly and easily. The aim of this study was to investigate eNO as surrogate marker for predicting a positive reaction in an exercise challenge in a cold chamber (ECC).

METHODS

A total of 143 subjects aged 6-45 years with suspected EIA were recruited for the study. The subjects underwent an eNO measurement, an ECC and a skin prick test (SPT). To define the sensitivity and specificity of eNO as predictor, a receiver-operating characteristic (ROC) curve was plotted. The individual probability of the occurrence of a positive reaction after ECC based on an eNO value was calculated using a logistic regression model.

RESULTS

An eNO cut-off value of 18.5 ppb (area under the curve (AUC) 0.71, p < 0.001) showed the best combination of sensitivity and specificity for a positive reaction (forced expiratory volume in 1 s (FEV₁) decrease ≥ 10% after ECC) for the whole group. An eNO cut-off value of 46.0 ppb had a specificity of 100.0% to predict a significant FEV₁ decrease and may save exercise testing in 22.4% of patients. A negative predictive level with a high sensitivity and negative predictive value (NPV) could not be defined. In the subgroup that was house dust might (HDM) allergy positive (HDM pos; n = 68, 45.5% of all subjects), an eNO cut-off value of 35.5 ppb (AUC 0.79, p < 0.01) showed the best combination of sensitivity and specificity for a positive reaction after the ECC with a specificity 100.0% and may save exercise testing in 45.6% of HDM pos patients. Using logistic regression, a 95% probability for a positive FEV₁ decrease after ECC was estimated at 53 ppb for the whole group and at 47 ppb for the HDM pos subgroup.

CONCLUSIONS

Exhaled NO measurement is a screening tool for EIA, especially in HDM pos subjects. In a real-life setting, a cut-off value of 46.0 ppb detects EIA at 100% in all suspected patients, and a cut-off level of 35.5 ppb is valuable marker of EIA in patients with an HDM allergy. These levels can save time and costs in a large proportion of patients and will be helpful for clinicians.

Association of exercise-induced wheeze and other asthma symptoms with emergency department visits and hospitalizations in a large cohort of urban adolescents

OBJECTIVE

Exercise-induced wheeze (EIW) has been found to be associated with asthma-related urgent care in school-aged children. Despite asthma's high prevalence and morbidity among adolescents, this association has not been examined in adolescents. We tested the association of EIW and other asthma symptoms to asthma-related ED visits and hospitalizations in urban adolescents with probable asthma. We hypothesized that EIW would be associated with urgent care.

METHODS

In this cross-sectional study 30,467 high school students (mean age = 16.0) from 49 NYC schools completed two brief validated measures, one assessing probable asthma and the other the frequency of six asthma symptoms over the past year. Adolescents also reported if in the past year they had an asthma-related ED visit or hospitalization. Analyses presented here included students with probable asthma (n = 9149). Using logistic regression, we modeled each asthma symptom as a function of ED visits and hospitalizations adjusting for sex, age, race/ethnicity and asthma severity. Multivariable models included all symptoms to account for the potential interaction between symptoms.

RESULTS

Among adolescents with probable asthma, EIW was associated with ED visits and hospitalizations. In multivariable models wheeze without a cold, chest tightness, night wakening, but not EIW, were significantly associated with both ED visits and hospitalizations.

CONCLUSIONS

Unlike findings with younger children, EIW does not appear to be associated with ED visits and hospitalizations among urban adolescents with probable asthma. Instead, symptoms, such as chest tightness and night wakening, appear to be important at identifying adolescents at risk for asthma-related urgent care.

Respiratory Function and Symptoms Post Cold Air Exercise in Female High and Low Ventilation Sport Athletes

Purpose

Cold weather exercise is common in many regions of the world; however, it is unclear whether respiratory function and symptom worsen progressively with colder air temperatures. Furthermore, it is unclear whether high-ventilation sport background exacerbates dysfunction and symptoms.

Methods

Seventeen active females (measure of the maximum volume of oxygen [VO_2max]: 49.6±6.6 mL·kg^-1·min^-1) completed on different days in random order 5 blinded running trials at 0℃, -5℃, -10℃, -15℃, and -20℃ (humidity 40%) in an environmental chamber. Distance, heart rate, and rating of perceived exertion (RPE) were measured within each trial; forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), forced expiratory flow at 25%-75% (FEF_25-75), and forced expiratory flow at 50% (FEF₅₀) were measured pre- and post-test (3, 6, 10, 15, and 20 minutes). Respiratory symptoms and global effort were measured post-test spirometry.

Results

Mean decreases were found in FEV1 (4%-5% at 0℃, -5℃, -10℃, and -15℃; 7% at -20℃). FEF_25-75 and FEF₅₀ decreased 7% and 11% at -15℃ and -20℃, respectively. Post-exertion spirometry results were decreased most at 3 to 6 minutes, recovering back to baseline at 20 minutes. Respiratory symptoms and global effort significantly increased at -15℃ and -20℃ with decreased heart rate. High-ventilation sports decreased function more than low-ventilation participants but had fewer symptoms.

Conclusions

These results indicate that intense exercise at cold air temperatures up to -20℃ is achievable; however, greater effort along with transient acute bronchoconstriction and symptoms of cough after exercising in temperatures colder than -15℃ are likely. It is recommended that individuals cover their mouth and reduce exercise intensity to ameliorate the effects of cold weather exercise.

Association between exercise-induced asthma and parental socio-economic status among school-aged adolescents in a semiurban community in Nigeria

This study investigated the prevalence and association between exercise-induced asthma (EIA) and parental socio-economic status (PSES) among school-aged adolescents in a semiurban community in Nigeria. Three hundred and eighty-five adolescents (185 male and 200 female adolescents) whose ages ranged between 10 and 19 years participated in this cross-sectional study. Participants were recruited from four government approved secondary schools in Ido-Ekiti using a multistage sampling technique. Peak expiratory flow rate (PEFR) was assessed at baseline and after 6-min run test (6-MRT) on a level playing ground using a standard peak flow meter. PEFR measurements were repeated at 5th, 10th, 15th, and 20th min post 6-MRT. Participants who had >15.0% PEFR fall were considered to have EIA. PSES was assessed using a validated socio-economic status questionnaire. Descriptive and inferential statistics were used to analyze data. Alpha level was set at P<0.05. The mean ages of males and females were 13.9±2.0 and 13.8±1.6 years, respectively. More than half of the participants, 58.2% had EIA (>15.0% PEFR scores) while 53.5% belonged to middle PSES class. There was no significant difference between PEFR scores of male and female participants at baseline and 5th min post 6-MRT. However, male participants had significant higher PEFR than the female counterparts at 10th (t=2.090, P=0.037), 15th (t=2.162, P=0.031), and 20th min (t=2.978, P=0.003). There was significant association between EIA and PSES (χ²=152.4; P=0.001). The prevalence of EIA is very high among school-aged adolescents in Nigeria and was significantly associated with PSES.

The acute response to interval and continuous exercise in adults with confirmed airway hyper-responsiveness

OBJECTIVES

To determine changes in lung function following an acute bout of high intensity interval exercise (HIIE), moderate intensity interval exercise (MIIE), and moderate intensity continuous exercise (MICE) in adults with airway hyper-responsiveness (AHR).

DESIGN

A randomized cross-over design was used.

METHODS

Participants completed five laboratory sessions: (1) eucapnic voluntary hyperpnea challenge (2) maximal exercise test to determine peak power output (PPO) and, (3-5) HIIE (90% PPO for 1min followed by 10% PPO for 1min, repeated 10 times), MIIE (65% PPO for 1min followed by 10% PPO for 1min, repeated 10 times) and MICE (65% PPO for 20min). Lung function was assessed pre and post-exercise.

RESULTS

Thirteen participants (age: 21.1±2.7years) with mild/moderate asthma completed all protocols. Lung function was significantly lower following the MICE (-14.8%±12.2) protocol compared to the HIIE (-7.1%±8.3) and MIIE (-4.5%±3.3).

CONCLUSIONS

It appears that MICE is associated with the greatest decline in post-exercise FEV₁ among those with AHR. Interval exercise may be better tolerated than continuous exercise among those with AHR.

Reported Exercise-Related Respiratory Symptoms and Exercise-Induced Bronchoconstriction in Asthmatic Children

Background

Unlimited physical activity is one of the key issues of asthma control and management. We investigated how reliable reported exercise-related respiratory symptoms (ERRS) are in predicting exercise-induced bronchoconstriction (EIB) in asthmatic children.

Methods

In this prospective study, 179 asthmatic children aged 7 - 15 years were asked for specific questions on respiratory symptoms related to exercise and allocated into two groups according to whether they complained about symptoms. Group I (n = 134) consisted of children answering “yes” to one or more of the questions and group II (n = 45) consisted of children answering “no” to all of the questions.

Results

Sixty-four of 179 children showed a positive exercise challenge test (ECT). There was no difference in the frequency of a positive test between children in group I (n = 48) and group II (n = 12) (P = 0.47). The sensitivity of a positive report for ERRS to predict a positive ECT was only 37%, with a specificity of 0.72.

Conclusion

According to current guidelines, the report or lack of ERRS has direct consequences on treatment decisions. However, the history of ERRS did not predict EIB and one-third of asthmatic children without complaints of ERRS developed EIB during the ECT. This raises the question of the need for objective measures of bronchial hyperresponsiveness (BHR) in pediatric asthma management.

Exploratory study comparing dysautonomia between asthmatic and non-asthmatic elite swimmers

BACKGROUND

Dysautonomia has been independently associated with training and exercise-induced bronchoconstriction. In addition, neurogenic airway inflammation was recently associated with swimmers-asthma. We aimed to assess the relation between autonomic nervous system and airway responsiveness of asthmatic elite swimmers.

METHODS

Twenty-seven elite swimmers, 11 of whom had asthma, were enrolled in this exploratory cross-sectional study. All performed spirometry with bronchodilation, skin prick tests and methacholine challenge according to the guidelines. Pupillometry was performed using PLR-200™ Pupillometer. One pupil light response curve for each eye was recorded and the mean values of pupil's maximal and minimal diameters, percentage of constriction, average and maximum constriction velocities (parasympathetic parameters), dilation velocity, and total time to recover 75% of the initial size (sympathetic parameters) were used for analysis. Asthma was defined using IOC-MC criteria; subjects were divided into airway hyperesponsiveness (AHR) severity according to methacholine PD20 in: no AHR, borderline, mild, moderate and severe AHR. Differences for pupillary parameters between groups and after categorization by AHR severity were assessed using SPSS 20.0 (p ≤ 0.05). In individuals with clinically relevant AHR, correlation between PD20 and pupillary parameters was investigated with Spearman's correlation test.

RESULTS

No statistically significant differences were observed between asthmatic and non-asthmatic swimmers regarding parasympathetic parameters. When stratified by AHR, maximal and minimal diameters and percentage of constriction were significantly lower among those with severe AHR. Among swimmers with clinically relevant AHR (n = 18), PD20 correlated with parasympathetic activity: maximal (r = 0.67, p = 0.002) and minimal diameters (r = 0.75, p<0.001), percentage of constriction (r = -0.59, p = 0.011) and latency (r = 0.490, p = 0.039).

CONCLUSIONS

No significant differences were observed between asthmatic and non-asthmatic swimmers regarding parasympathetic parameters, but among those with relevant AHR an association was found. Although limited by the sample size, these findings support the relation between dysautonomia and AHR in asthmatic swimmers.

The effect of vitamin C on bronchoconstriction and respiratory symptoms caused by exercise: a review and statistical analysis

Physical activity increases oxidative stress and therefore the antioxidant effects of vitamin C administration might become evident in people undertaking vigorous exercise. Vitamin C is involved in the metabolism of histamine, prostaglandins, and cysteinyl leukotrienes, all of which appear to be mediators in the pathogenesis of exercise-induced bronchoconstriction (EIB). Three studies assessing the effect of vitamin C on patients with EIB were subjected to a meta-analysis and revealed that vitamin C reduced postexercise FEV1 decline by 48% (95% CI: 33% to 64%). The correlation between postexercise FEV1 decline and respiratory symptoms associated with exercise is poor, yet symptoms are the most relevant to patients. Five other studies examined subjects who were under short-term, heavy physical stress and revealed that vitamin C reduced the incidence of respiratory symptoms by 52% (95% CI: 36% to 65%). Another trial reported that vitamin C halved the duration of the respiratory symptoms in male adolescent competitive swimmers. Although FEV1 is the standard outcome for assessing EIB, other outcomes may provide additional information. In particular, the mean postexercise decline of FEF50 is twice the decline of FEV1. Schachter and Schlesinger (1982) reported the effect of vitamin C on exercise-induced FEF60 levels in 12 patients suffering from EIB and their data are analyzed in this paper. The postexercise FEF60 decline was greater than 60% for five participants and such a dramatic decline indicates that the absolute postexercise FEF60 level becomes an important outcome in its own right. Vitamin C increased postexercise FEF60 levels by 50% to 150% in those five participants, but had no significant effect in the other seven participants. Thus, future research on the effects of vitamin C on EIB should not be restricted to measuring only FEV1. Vitamin C is inexpensive and safe, and further study on those people who have EIB or respiratory symptoms associated with exercise is warranted.

Developing and emerging clinical asthma phenotypes

For more than a century, clinicians have attempted to subdivide asthma into different phenotypes based on triggers that cause asthma attacks, the course of the disease, or the prognosis. The first phenotypes that were described included allergic asthma, intrinsic or nonallergic asthma, infectious asthma, and aspirin-exacerbated asthma. These phenotypes are being reviewed elsewhere in this issue of the journal. The present article focuses on developing and emerging clinical asthma phenotypes. First, asthma phenotypes that are associated with environmental exposures (occupational agents, cigarette smoke, air pollution, cold dry air); second, asthma phenotypes that are associated with specific symptoms or clinical characteristics (cough, obesity, adult onset of disease); and third, asthma phenotypes that are based on biomarkers. This latter approach is the most promising because it attempts to identify asthma phenotypes with different underlying mechanisms so that therapies can be better targeted toward disease-specific features and disease outcomes can be improved.

Exercise-induced asthma: fresh insights and an overview

Exercise-induced asthma (EIA) is a common condition affecting 12-15% of the population. Ninety percent of asthmatic individuals and 35-45% of patients with allergic rhinitis are afflicted by EIA, while 3-10% of the general population is also believed to suffer from this condition. EIA is a condition which is more prevalent in strenuous outdoor, cold weather and winter sports. The pathophysiology of EIA continues to intrigue medical physiologists. However, the water-loss hypothesis and the post-exertional airway-rewarming hypothesis are as yet the best accepted theories. EIA is best diagnosed by a good medical history and a free-run challenge test. A post-exertion decrease by 15% in FEV1 and PEFR is diagnostic of EIA. Sensitivity of exercise testing ranges from 55% to 80% while specificity is as high as 93%. EIA is a disorder that can be successfully treated by combining both non-pharmacological and pharmacological treatment options. Prompt diagnosis and treatment of this condition is vital if we hope to provide our patients with better overall health, better social life and a better self-image.