Exercise capacity and exercise-induced bronchoconstriction (EIB) in a cold environment

Association of temperature and absolute humidity with incidence of exercise-induced bronchoconstriction in children

AIM

Exercise test outdoors is widely used to diagnose asthma in children, but it is unclear how much outdoor air factors affect the results.

METHODS

We analysed 321 outdoor exercise challenge tests with spirometry in children 6-16 years conducted due to suspicion of asthma or for assessing the effect of medication on asthma. We studied the association of FEV1 decrease and incidence of exercise-induced bronchoconstriction (EIB) with temperature, relative humidity (RH) and absolute humidity (AH).

RESULTS

Asthma was diagnosed in 57% of the subjects. AH ≥5 g/m3, but not RH or temperature, was associated with the EIB incidence (p = 0.035). In multivariable logistic regression, AH ≥5 g/m3 was negatively associated (OR = 0.51, 95% CI [0.28─0.92], p = 0.026) while obstruction before exercise (OR = 2.11, 95% CI [1.16─3.86], p = 0.015) and IgE-mediated sensitisation were positively associated with EIB (OR = 2.24, 95% CI [1.11─4.51], p = 0.025). AH (r = -0.12, p = 0.028) and temperature (r = -0.13, p = 0.023) correlated with decrease in FEV1. In multivariable linear regression, only AH was associated with FEV1 decrease (coefficient = -0.044, 95% CI [-0.085 to -0.004], p = 0.033).

CONCLUSION

AH of outdoor air associates with occurrence and severity of EIB in outdoor exercise tests in children. Care should be taken when interpreting negative outdoor exercise test results if AH of air is high.

Independent, additive and interactive effects of acute normobaric hypoxia and cold on submaximal and maximal endurance exercise

PURPOSE

To evaluate the independent and combined effects of hypoxia (FiO2 = 13.5%) and cold (- 20 °C) on physiological and perceptual responses to endurance exercise.

METHODS

14 trained male subjects ( V . O2max: 64 ± 5 mL/kg/min) randomly performed a discontinuous maximal incremental test to exhaustion on a motorized treadmill under four environmental conditions: Normothermic-Normoxia (N), Normothermic-Hypoxia (H), Cold-Normoxia (C) and Cold-Hypoxia (CH). Performance and physiological and perceptual responses throughout exercise were evaluated.

RESULTS

Maximal WorkLoad (WL) and WL at lactate threshold (LT) were reduced in C (- 2.3% and - 3.5%) and H (- 18.0% and - 21.7%) compared to N, with no interactive (p = 0.25 and 0.81) but additive effect in CH (- 21.5% and - 24.6%). Similarly, HRmax and Vemax were reduced in C (- 3.2% and - 14.6%) and H (- 5.0% and - 7%), showing additive effects in CH (- 7.7% and - 16.6%). At LT, additive effect of C (- 2.8%) and H (- 3.8%) on HR reduction in CH (- 5.7%) was maintained, whereas an interactive effect (p = 0.007) of the two stressors combined was noted on Ve (C: - 3.1%, H: + 5.5%, CH: - 10.9%). [La] curve shifted on the left in CH, displaying an interaction effect between the 2 stressors on this parameter. Finally, RPE at LT was exclusively reduced by hypoxia (p < 0.001), whereas TSmax is synergistically reduced by cold and hypoxia (interaction p = 0.047).

CONCLUSION

If compared to single stress exposure, exercise performance and physiological and perceptual variables undergo additive or synergistic effects when cold and hypoxia are combined. These results provide new insight into human physiological responses to extreme environments.

Asthma and exercise-induced bronchoconstriction in athletes: Diagnosis, treatment, and anti-doping challenges

Athletes often experience lower airway dysfunction, such as asthma and exercise-induced bronchoconstriction (EIB), which affects more than half the athletes in some sports, not least in endurance sports. Symptoms include coughing, wheezing, and breathlessness, alongside airway narrowing, hyperresponsiveness, and inflammation. Early diagnosis and management are essential. Not only because untreated or poorly managed asthma and EIB potentially affects competition performance and training, but also because untreated airway inflammation can result in airway epithelial damage, remodeling, and fibrosis. Asthma and EIB do not hinder performance, as advancements in treatment strategies have made it possible for affected athletes to compete at the highest level. However, practitioners and athletes must ensure that the treatment complies with general guidelines and anti-doping regulations to prevent the risk of a doping sanction because of inadvertently exceeding specified dosing limits. In this review, we describe considerations and challenges in diagnosing and managing athletes with asthma and EIB. We also discuss challenges facing athletes with asthma and EIB, while also being subject to anti-doping regulations.

A longitudinal study of exercise-induced bronchoconstriction and laryngeal obstruction in high school athletes

BACKGROUND

Exercise-induced bronchoconstriction (EIB) and exercise-induced laryngeal obstruction (EILO) are common in elite athletes. Knowledge of which factors are related to incident EIB and EILO is limited. The aim of this study was to explore the course of EIB and EILO in adolescent athletes over a 2 years period and baseline characteristics related to incident EIB.

METHODS

Questionnaire data on respiratory symptoms, asthma, and aeroallergy and results of objective EIB and EILO tests were collected from 58 participants (27 tested for EILO) at baseline and after 2 years (follow-up). Associations between incident EIB and baseline asthma-like symptoms, exercise-induced symptoms, fractional exhaled nitric oxide (FeNO), aeroallergy, and sex were assessed using logistic regression models.

RESULTS

Ten participants had incident EIB, and eight participants had persistent EIB. Five were EIB positive at baseline but negative at follow-up, while 35 participants were EIB negative at both time points. Having incident EIB was associated with reporting waking up with chest tightness (OR = 4.38; 95% CI: 1.06, 22.09). Reporting an increased number of asthma-like symptoms increased the likelihood of incident EIB (OR = 2.78; 95% CI: 1.16, 6.58). No associations were found between exercise-induced symptoms, FeNO, aeroallergy, or sex and incident EIB. Incident EILO was found in three and persistent EILO in two of the 27 participants tested.

CONCLUSION

Two in nine had incident EIB and one eighth had incident EILO, suggesting that recurrent testing for EIB and EILO may be relevant in young athletes. Particularly, EIB-negative athletes reporting multiple asthma-like symptoms could benefit from recurrent EIB testing.

Practicing Sport in Cold Environments: Practical Recommendations to Improve Sport Performance and Reduce Negative Health Outcomes

Although not a barrier to perform sport, cold weather environments (low ambient temperature, high wind speeds, and increased precipitation, i.e., rain/water/snow) may influence sport performance. Despite the obvious requirement for practical recommendations and guidelines to better facilitate training and competition in such cold environments, the current scientific evidence-base is lacking. Nonetheless, this review summarizes the current available knowledge specifically related to the physiological impact of cold exposure, in an attempt to provide practitioners and coaches alike with practical recommendations to minimize any potential negative performance effects, mitigate health issues, and best optimize athlete preparation across various sporting disciplines. Herein, the review is split into sections which explore some of the key physiological effects of cold exposure on performance (i.e., endurance exercise capacity and explosive athletic power), potential health issues (short-term and long-term), and what is currently known with regard to best preparation or mitigation strategies considered to negate the potential negative effects of cold on performance. Specific focus is given to "winter" sports that are usually completed in cold environments and practical recommendations for physical preparation.

Exercise-Induced Bronchoconstriction in Iraq and Afghanistan Veterans With Deployment-Related Exposures

INTRODUCTION

Acute exposure to high-levels of ambient fine particulate matter while exercising results in airway narrowing, but the long-term effects of repeated exposure on exercise-induced bronchoconstriction (EIB) are not well known. The goal of this preliminary study is to determine the rate of EIB among a sample of non-treatment seeking veterans deployed to Iraq and Afghanistan.

MATERIALS AND METHODS

Twenty-four veterans (median [interquartile range]: 35.0 [27.3, 45] years) without history of asthma volunteered for this study. Spirometry was assessed before and after a standardized exercise challenge. A positive EIB response was defined as an exercise-induced fall in forced expiatory volume in 1 second ≥10%. Secondary criteria (peak flow ≥10% or mid-expiratory flow ≥15%) were also considered as an estimate of probable EIB.

RESULTS

A positive EIB response was observed in 16.7% and probable EIB response was observed in 41.7% of our sample. Median deployment length to Iraq or Afghanistan was 13.0 [10.3, 17.5] months and the median time since deployment was 4.2 [2.7, 7.7] years. At the time of testing, veterans reported persistent cough (58.3%), wheeze (37.5%), and shortness of breath (37.5%). During deployment, veterans reported exposure to dust and sand (70.8%), smoke from burn pits (66.7%), vehicle exhaust (83.3%), and regional air pollution (26.0%) on most days or daily.

CONCLUSIONS

Approximately 17% of our sample of non-treatment seeking deployed Iraq and Afghanistan veterans demonstrated EIB, similar to the general population prevalence. However, persistent respiratory symptoms and alternative indices of probable EIB supports continued monitoring of this population.

A heat and moisture-exchanging mask impairs self-paced maximal running performance in a sub-zero environment

Purpose

Heat-and-moisture-exchanging devices (HME) are commonly used by endurance athletes during training in sub-zero environments, but their effects on performance are unknown. We investigated the influence of HME usage on running performance at − 15 °C.

Methods

Twenty-three healthy adults (15 male, 8 female; age 18–53 years; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text O}_{2peak}$$\end{document}V˙O2peak men 56 ± 7, women 50 ± 4 mL·kg⁻¹·min⁻¹) performed two treadmill exercise tests with and without a mask-style HME in a randomised, crossover design. Participants performed a 30-min submaximal warm-up (SUB), followed by a 4-min maximal, self-paced running time-trial (TT). Heart rate (HR), respiratory frequency (f_R), and thoracic area skin temperature (T_sk) were monitored using a chest-strap device; muscle oxygenation (SmO₂) and deoxyhaemoglobin concentration ([HHb]) were derived from near-infra-red-spectroscopy sensors on m. vastus lateralis; blood lactate was measured 2 min before and after the TT.

Results

HME usage reduced distance covered in the TT by 1.4%, despite similar perceived exertion, HR, f_R, and lactate accumulation. The magnitude of the negative effect of the HME on performance was positively associated with body mass (r² = 0.22). SmO₂ and [HHb] were 3.1% lower and 0.35 arb. unit higher, respectively, during the TT with HME, and T_sk was 0.66 °C higher during the HME TT in men. HR (+ 2.7 beats·min⁻¹) and T_sk (+ 0.34 °C) were higher during SUB with HME. In the male participants, SmO₂ was 3.8% lower and [HHb] 0.42 arb. unit higher during SUB with HME.

Conclusion

Our findings suggest that HME usage impairs maximal running performance and increases the physiological demands of submaximal exercise.

Are Respiratory Responses to Cold Air Exercise Different in Females Compared to Males? Implications for Exercise in Cold Air Environments

Research has shown that cold air exercise causes significant respiratory dysfunction, especially in female athletes. However, how female and male athletes respond to cold air exercise is not known. Thus, we aimed to compare acute respiratory responses (function, recovery and symptoms) in males and females after high-intensity cold air exercise. Eighteen (nine female) athletes completed two environmental chamber running trials at 0 °C and −20 °C (humidity 34 ± 5%) on different days in a randomized starting order. Spirometry was performed pre, 3, 6, 10, 15 and 20 min post. Respiratory symptoms were measured posttrial and heart rate and rating of perceived exertion were assessed during each trial. No significant differences in delta change (pre to post) were found at either temperature between sexes for FEV₁, FVC, FEF50% and FEF25–75%. At −20 °C, FEV₁ decreased similarly in both sexes (males: 7.5%, females: 6.3%) but not at 0 °C, p = 0.003. Postexertion respiratory function recovery and reported symptoms were not different between sexes at either temperature. These results indicate no sex-based differences in acute respiratory responses (function, recovery and symptoms) to cold air exercise. However, intense exercise at −20 °C is challenging to the respiratory system in both sexes and may lead to altered respiratory responses compared to mild winter conditions like 0 °C.

Exercise in Sub-zero Temperatures and Airway Health: Implications for Athletes With Special Focus on Heat-and-Moisture-Exchanging Breathing Devices

Asthma is highly prevalent among winter endurance athletes. This "occupational disease" of cross-country skiers, among others, was acknowledged during the 1990s, with the pathogenesis attributed to repeated and prolonged exposure to cold, dry air combined with high rates of ventilation during exercise. Nevertheless, more than 25 years later, the prevalence of asthma among Scandinavian cross-country skiers is unchanged, and prevention remains a primary concern for sports physicians. Heat-and-moisture-exchanging breathing devices (HMEs) prevent exercise-induced bronchoconstriction in subjects with pre-existing disease and may have potential as a preventative intervention for healthy athletes undertaking training and competition in winter endurance sports. Herein we firstly provide an overview of the influence of temperature and humidity on airway health and the implications for athletes training and competing in sub-zero temperatures. We thereafter describe the properties and effects of HMEs, identify gaps in current understanding, and suggest avenues for future research.

Effects of a heat and moisture exchanger on respiratory function and symptoms post-cold air exercise

PURPOSE

Exercise at temperatures below -15°C induces drying and cooling of lung airways which causes exercise-induced bronchoconstriction (EIB) and respiratory symptoms, especially in winter sport athletes. The objective of this study was to evaluate whether a heat and moisture exchanger (HME) worn during intense cold air exercise improves lung function and reduces respiratory symptoms in healthy winter sport athletes.

METHODS

Seven active males and six active females (maximum oxygen uptake 61.9 ± 6.9 and 52.2 ± 5.3 mL/kg/min), all active or former winter sport athletes, completed running trials with and without HME in random order on 2 days in an environmental chamber (-20°C temperature, humidity 46.2%). Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁ ), forced expiratory flow at 25%-75% (FEF_25%-75% ), and FEF at 50% (FEF_50% ) were measured pre- and post-exercise (3, 6, 10, 15, and 20 minutes). Respiratory symptoms were reported after exercise.

RESULTS

Significant interaction effects were observed for FEV₁ and FEF_25%-75% . Mean decrease of FVC (-5.9%, P ≤ .001) and FEV₁ (-4.2%, P = .003) was largest 3 minutes post-exercise without HME. There was an increase of FEV₁ , FEF_25%-75% , and FEF_50% post-exercise compared to pre-exercise with HME. More respiratory symptoms overall were reported without HME (P = .046).

CONCLUSION

Intense cold air exercise likely causes transient acute bronchoconstriction and symptoms of cough in individuals participating in winter sports. However, this study finds that the application of an HME during intense cold air exercise improves lung function and reduces prevalence of EIB-associated symptoms compared to unprotected intense cold air exercise.

Cold air exercise screening for exercise induced bronchoconstriction in cold weather athletes

Exercise Induced Bronchoconstriction (EIB) prevalence in cold weather athletes is high. Currently, no standardized cold air exercise provocation test exists. Thus we aimed to determine EIB prevalence using a Cold Air Test (CAT; 5 km outdoor running; -15 °C) compared to the most common EIB screen the Eucapnic Voluntary Hyperpnea (EVH) test in cold weather athletes. Sixteen (9 male; 20-35 years old) cold weather athletes completed EVH 72 h before CAT. Spirometry, Fractional Expired Nitric Oxide (FENO), respiratory symptoms were measured and atopy status was determined. Five and 7 participants were EIB + on the EVH and CAT, respectively. Level of agreement was 50% between tests. FEV₁ recovery was significantly prolonged and Peak Expiratory Flow was decreased after CAT compared to EVH. Predictive characteristics of EIB + included FENO >12 ppb, FEV₁/FVC ratio (<0.75) and BMI < 20. EVH does not always reflect EIB triggered by cold weather exercise. More research is required to understand the best EIB screens for cold weather athletes.

Pharmacologic Strategies for Exercise-Induced Bronchospasm with a Focus on Athletes

Exercise-induced bronchoconstriction (EIB) is the transient narrowing of the airways during and after exercise that occurs in response to increased ventilation in susceptible individuals. It occurs across the age spectrum in patients with underlying asthma and can occur in athletes without baseline asthma. The inflammatory mechanisms underlying EIB in patients without asthma may be distinct from those underlying EIB in patients with asthma. This review summarizes mechanistic and clinical data that can guide the choice of chronic and acute pharmacologic therapies targeting control of EIB. Relevant regulations from the World Anti-Doping Agency are also discussed.

Impact of detecting and treating exercise-induced bronchoconstriction in elite footballers

Our aim was to evaluate the prevalence of exercise-induced bronchoconstriction (EIB) in elite football players and assess subsequent impact of therapy on airway health and exercise performance. 97 male professional football players completed an airway health assessment with a eucapnic voluntary hyperpnoea (EVH) challenge to diagnose EIB. Players demonstrating a positive result (EVH+) were prescribed inhaler therapy depending on severity, including inhaled corticosteroids and inhaled short-acting β2-agonists, and underwent repeat assessment after 9 weeks of treatment. Eight players (EVH+ n=3, EVH- n=5) completed a peak oxygen uptake (V'O2peak) test at initial and follow-up assessment. Out of the 97 players, 27 (28%) demonstrated a positive EVH result. Of these, 10 had no prior history (37%) of EIB or asthma. EVH outcome was not predictable by respiratory symptoms. Seven (24%) of the 27 EVH+ players attended follow-up and demonstrated improved post-challenge spirometry (forced expiratory volume in 1 s pre-test -22.9±15.4%, post-test -9.0±1.6%; p=0.018). At follow-up V'O2peak improved by 3.4±2.9 mL·kg-1·min-1 in EVH+ players compared to 0.1±2.3 mL·kg-1·min-1 in EVH- players. Magnitude of inference analysis indicated treatment was possibly beneficial (74%) for exercise capacity. Elite football players have a high EIB prevalence. Treatment with inhaler therapy reduces EIB severity.

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.

Field versus race pace conditions to provoke exercise-induced bronchoconstriction in elite swimmers: Influence of training background

Background

Diagnosing Airway hyper-responsiveness (AHR) requires bronchial provocation tests that are performed at rest and after exercise or hyperventilation in either a lab or field setting. Presently, it is unclear whether the proposed AHR field test for swimming induces sufficient provocation due to lack of intensity. Thus we aimed to examine how the 8 minute field swim test compared to all out racing and a lower intensity practice exposure affected AHR. We hypothesized that the race would affect AHR the most thereby highlighting the importance of maximal effort in swim AHR.

Methods

10 female and 15 male swimmers completed three conditions (sanctioned race of different distances, 8 min field swim challenge and swim practice). Forced vital capacity (FVC), forced expired volume in 1 second (FEV₁) and forced expiratory flow (FEF_25-75) were measured at rest and after each exercise condition (at 6 and 10 min) in accordance with standard protocols. AHR was defined as a decrease in FEV₁ of ≥10% post exercise.

Results

A significant increase in FEV₁ and FEF_25-75 was observed for both post swim field test and post-race. The practice condition reduced FEV₁ in 44% of swimmers although the magnitude of change was small. There was a wide variability in the individual responses to the 3 conditions and AHR was diagnosed in one swimmer (race condition).

Conclusion

All conditions have poor sensitivity to diagnose EIB and total accumulated ventilation (distance swum) did not influence AHR. These results also indicate that elite swimmers, despite many risk factors, are not limited by respiratory function in race conditions. It is proposed that the swim field test not be used for AHR assessment in swimmers due to too high relative humidity.

Exercice-induced bronchoconstriction among athletes: Assessment of bronchial provocation tests

Diagnosis of exercise-induced bronchoconstriction (EIB) requires the use of bronchial provocation tests (BPTs). We assessed exercise-induced respiratory symptoms (EIRS), EIB and asthma in athletes and evaluated the validity of BPTs in the diagnosis of EIB. Rhinitis and atopy were also assessed. Athletes with (n=55) and without previous asthma diagnosis (n=145) were tested by skin prick tests, lung function and eNO measurements. EIRS were recorded and EIB was assessed by methacholine (Mch), eucapnic voluntary hyperpnoea (EVH), mannitol and exercise test. EIRS were highly reported and history of asthma was common among athletes. A high prevalence of atopy (48.7%) and allergic rhinitis (30.5%) was found. Athletes with asthma had a higher response rate to Mch and to EVH, as compared with athletes without a previous asthma diagnosis (P=0.012 and P=0.017 respectively). Report of EIRS, rhinitis and atopy were not associated with a positive BPT response. Screening athletes for EIB using BPTs is suggested, irrespective of reported EIRS or a previous asthma diagnosis.

Monitoring asthma in childhood: lung function, bronchial responsiveness and inflammation

This review focuses on the methods available for measuring reversible airways obstruction, bronchial hyperresponsiveness (BHR) and inflammation as hallmarks of asthma, and their role in monitoring children with asthma. Persistent bronchial obstruction may occur in asymptomatic children and is considered a risk factor for severe asthma episodes and is associated with poor asthma outcome. Annual measurement of forced expiratory volume in 1 s using office based spirometry is considered useful. Other lung function measurements including the assessment of BHR may be reserved for children with possible exercise limitations, poor symptom perception and those not responding to their current treatment or with atypical asthma symptoms, and performed on a higher specialty level. To date, for most methods of measuring lung function there are no proper randomised controlled or large longitudinal studies available to establish their role in asthma management in children. Noninvasive biomarkers for monitoring inflammation in children are available, for example the measurement of exhaled nitric oxide fraction, and the assessment of induced sputum cytology or inflammatory mediators in the exhaled breath condensate. However, their role and usefulness in routine clinical practice to monitor and guide therapy remains unclear, and therefore, their use should be reserved for selected cases.

The impact of exercise-induced bronchoconstriction on athletic performance: a systematic review

BACKGROUND

Exercise-induced bronchoconstriction (EIB) describes the phenomenon of transient airway narrowing in association with physical activity. Although it may seem likely that EIB would have a detrimental impact on athletic performance, this has yet to be established.

OBJECTIVES

The aim of this review is to provide a systematic appraisal of the current status of knowledge regarding EIB and exercise performance and to highlight potential mechanisms by which performance may be compromised by EIB.

DATA SOURCES AND STUDY SELECTION

PubMed/Medline and EBSCO databases were searched up to May 2014 using the search parameter: [('exercise' OR 'athlete') AND ('asthma' OR 'bronchoconstriction' OR 'hypersensitivity') AND 'performance']. This search string returned 243 citations. After systematically reviewing all of the abstracts, 101 duplicate papers were removed, with 132 papers excluded for not including an exercise performance outcome measure.

RESULTS

The remaining ten studies that met the initial criteria were included in this review; six evaluated the performance of physically active individuals with asthma and/or EIB while four assessed the effects of medication on performance in a comparable population.

CONCLUSION

The evidence concludes that whilst it is reasonable to suspect that EIB does impact athletic performance, there is currently insufficient evidence to provide a definitive answer.

Mitochondrial plasticity with exercise training and extreme environments

Mitochondria form a reticulum in skeletal muscle. Exercise training stimulates mitochondrial biogenesis, yet an emerging hypothesis is that training also induces qualitative regulatory changes. Substrate oxidation, oxygen affinity, and biochemical coupling efficiency may be regulated differentially with training and exposure to extreme environments. Threshold training doses inducing mitochondrial upregulation remain to be elucidated considering fitness level.

Assessment of EIB: What you need to know to optimize test results

Respiratory symptoms and asthma control questionnaires are poor predictors of the presence or severity of exercise-induced bronchoconstriction (EIB), and objective measurement is recommended. To optimize the chance of a positive test result, there are several factors to consider when exercising patients for EIB, including the ventilation achieved and sustained during exercise, water content of the inspired air, and the natural variability of the response. The high rate of negative exercise test results has led to the development of surrogates to identify EIB in laboratory or office settings, including eucapnic voluntary hyperpnea of dry air and inhalation of hyperosmolar aerosols.

Pathogenesis of exercise-induced bronchoconstriction

This article presents the various potential mechanisms responsible for the development of exercise-induced bronchoconstriction (EIB). Although the etiology of EIB is multifactorial, and the physiologic processes involved may vary between individuals (especially between those with and without asthma), drying of the small airways with an associated inflammatory response seems prerequisite for EIB. Dysregulated repair processes following exercise-induced airway epithelial injury may also serve as basis for EIB development/progression.

Effects of salmeterol on skeletal muscle cells: metabolic and proapoptotic features

PURPOSE

Salmeterol is a β2-adrenergic receptor agonist widely used for the treatment of asthma and chronic obstructive pulmonary disease. It has been shown that salmeterol is also used at supratherapeutic doses as performance-enhancing substance in sport practice. Although the abuse of β-agonists might determine some adverse effects, the molecular effects of salmeterol on skeletal muscle cells remain unclear.

METHODS

We evaluated the effects of salmeterol (0.1-10 μM) on both proliferative and differentiated rat L6C5 and mouse C2C12 skeletal muscle cell lines. The metabolic effects were evaluated by glyceraldehyde phosphate dehydrogenase, lactate dehydrogenase, citrate synthase, 3-OH acyl-CoA dehydrogenase, and alanine transglutaminase activities. Cytotoxic and apoptotic effects were analyzed by 3-(4,5-dimethylthiazol-1)-5-(3-carboxymeth-oxyphenyl)-2H-tetrazolium, trypan blue exclusion assay, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, Western blot analysis, and immunofluorescence staining.

RESULTS

We showed that salmeterol reduced the growth rate of proliferating cells in a dose- and time-dependent manner (6-48 h). An increase in oxidative metabolism was found after 6 h in C2C12 and L6C5 myoblasts and in C2C12 myotubes with respect to control cells, while in L6C5 myotubes, anaerobic metabolism prevailed. Exposure of myoblasts and myotubes for 48 and 72 h at high salmeterol concentrations induced apoptosis by the activation of the intrinsic apoptotic pathway, as confirmed by the modulation of the apoptotic proteins Bcl-xL, caspase-9, and poly (ADP-ribose) polymerase and by the cytoplasmic release of Smac/DIABLO.

CONCLUSIONS

Altogether, our results demonstrate that short-term supratherapeutic salmeterol exposure increased oxidative metabolic pathways on skeletal muscle cells, whereas prolonged treatment inhibits cell growth and exerts either a cytostatic or a proapoptotic effect in a time- and dose-dependent way.

Misdiagnosis of exercise-induced bronchoconstriction in professional soccer players

BACKGROUND

Physicians typically rely heavily on self-reported symptoms to make a diagnosis of exercise-induced bronchoconstriction (EIB). However, in elite sport, respiratory symptoms have poor diagnostic value. In 2009, following a change in international sports regulations, all elite athletes suspected of asthma and/or EIB were required to undergo pulmonary function testing (PFT) to permit the use of inhaled β(2)-agonists. The aim of this study was to examine the diagnostic accuracy of physician diagnosis of asthma/EIB in English professional soccer players.

METHODS

Sixty-five players with a physician diagnosis of asthma/EIB were referred for pulmonary function assessment. Medication usage and respiratory symptoms were recorded by questionnaire. A bronchial provocation test with dry air was conducted in 42 players and a mannitol challenge in 18 players. Five players with abnormal resting spirometry performed a bronchodilator test.

RESULTS

Of the 65 players assessed, 57 (88%) indicated regular use of asthma medication. Respiratory symptoms during exercise were reported by 57 (88%) players. Only 33 (51%) of the players tested had a positive bronchodilator or bronchial provocation test. Neither symptoms nor the use of inhaled corticosteroids were predictive of pulmonary function tests' outcome.

CONCLUSION

A high proportion of English professional soccer players medicated for asthma/EIB (a third with reliever therapy only) do not present reversible airway obstruction or airway hyperresponsiveness to indirect stimuli. This underlines the importance of objective PFT to support a symptoms-based diagnosis of asthma/EIB in athletes.

Lifestyle and the Respiratory Health of Children

This article offers a review of the potential influences of personal lifestyle on respiratory health in children, looking at both healthy individuals and those with respiratory disorders. As with many aspects of health, regular physical activity, an appropriate diet, and avoidance of obesity and cigarette smoke all contribute to optimal development of the healthy child. An active lifestyle is associated with greater static and dynamic lung volumes, greater efficiency of the ventilatory process, and an optimization of breathing patterns. The risk of upper respiratory infections is also reduced in those maintaining a moderate level of physical activity. Maternal smoking during pregnancy, as well as active and passive smoking, all have an adverse influence on lung function in the child, the largest effects being on dynamic lung volumes. The risk of developing asthma seems reduced in children who maintain a normal body mass and are physically active. A program of graded physical activity is of therapeutic value in a number of established respiratory conditions, including asthma, cystic fibrosis, and ventilatory impairment from neuromuscular disorders. Exercise carries a slight risk of fatalities from asthma and anaphylactic reactions. In designing an optimal physical activity program, it is also important to guard against the hazards of deep oronasal breathing, including the precipitation of bronchospasm by the inhalation of cold, dry air and pollens; an increased exposure to atmospheric pollutants (reducing and oxidant smog, fine and ultra-fine particulates, and carbon monoxide); and possible long-term dangers from chlorine derivatives in the atmosphere of indoor swimming pools.

Current concepts in the diagnosis and management of exercise-induced bronchospasm

Exercise-induced bronchospasm (EIB) is a common occurrence in individuals with asthma, though it can also affect individuals without asthma. It occurs frequently in athletes. Common symptoms include coughing, dyspnea, chest tightness, and wheezing; however, there can be a variety of more subtle symptoms. The differential diagnosis of EIB is broad and includes several pulmonary and cardiac disorders. During the initial evaluation, a complete history, physical examination, and spirometry should be performed. In most patients with EIB, the baseline spirometry is normal; therefore, bronchoprovocation testing is strongly recommended. Both pharmacologic and nonpharmacologic approaches are important in the treatment of EIB. Management of EIB on the sideline of athletic events requires preparation and immediate access to rescue inhalers.

Physical Activity in Childhood Asthma: Friend or Foe?

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

[Exercise-induced bronchoconstriction in non-asthmatic athletes]

INTRODUCTION

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

STATE OF ART

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

PERSPECTIVES

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

CONCLUSIONS

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

Exercise-induced asthma: critical analysis of the protective role of montelukast

Exercise-induced asthma/exercise-induced bronchospasm (EIA/EIB) is a prevalent and clinically important disease affecting young children through older adulthood. These terms are often used interchangeably and the differences are not clearly defined in the literature. The pathogenesis of EIA/EIB may be different in those with persistent asthma compared to those with exercise-induced symptoms only. The natural history of EIA is unclear and may be different for elite athletes. Leukotriene biology has helped the understanding of EIB. The type and intensity of exercise are important factors for EIB. Exercise participation is necessary for proper development and control of EIA is recommended. Symptoms of EIB should be confirmed by proper testing. Biologic markers may also be helpful in diagnosis. Not all exercise symptoms are from EIB. Many medication and nonpharmacologic treatments are available. Asthma education is an important component of managing EIA. Many medications have been tested and the comparisons are complicated. Montelukast is a US Food and Drug Administration-approved asthma and EIB controller and has a number of potential advantages to other asthma medications including short onset of action, ease of use, and lack of tolerance. Not all patients improve with montelukast and rescue medication should be available.

Athletic trainers' experience and comfort with evaluation and management of asthma: a pilot study

BACKGROUND

Approximately 10% to 50% of competitive athletes experience asthma symptoms with exercise, due to either chronic asthma or exercise-induced bronchospasm. Early recognition and management of asthma symptoms may improve athletic performance and quality of life for athletes with asthma or exercise-induced bronchospasm. Athletic trainers may have frequent opportunities to identify asthma symptoms and assist athletes with management.

OBJECTIVE

To survey athletic trainers about their experience and comfort with evaluation and management of asthma symptoms in athletes and identify athletic trainer characteristics associated with higher comfort levels.

DESIGN AND SETTING

A 2005 cross-sectional survey of National Athletic Trainers' Association and Illinois Athletic Trainers Association members.

PARTICIPANTS

A total of 304 athletic trainers.

DATA COLLECTION AND ANALYSIS

Respondents completed a Web-based survey reporting years of experience, competitive level of athletes supervised, satisfaction with asthma education, experience evaluating asthma symptoms, and comfort managing asthma.

RESULTS

Response rate was 13.9% (304 of 2,175). At least 23% of respondents evaluated asthma symptoms five or more times the previous year. Respondents working exclusively with junior high and/or high school athletes evaluated asthma symptoms more frequently than those working exclusively with college and/or professional athletes. Fifty-eight percent of respondents were unsatisfied with their asthma education. Only 25.3% were "very" comfortable managing asthma. Respondents with higher comfort levels evaluated asthma symptoms more frequently (p < 0.01, r = 0.18) and were more likely to be satisfied with their asthma education (p < 0.001). Over 95% of respondents endorsed more asthma education in athletic training curricula.

CONCLUSIONS

Results of this pilot study indicate that athletic trainers have opportunities to help athletes manage asthma symptoms that can compromise athletic performance or limit sports participation. However, few athletic trainers are very comfortable managing asthma, and most are unsatisfied with their asthma education. Further study is needed to determine the effect of enhanced asthma education on athletic trainers' comfort and skills with asthma evaluation and management.

Exercise-induced bronchoconstriction in athletes-should we screen?

The fact that exercise-induced bronchoconstriction (EIB) may be both over- and underdiagnosed in athletes has led to calls for widespread screening for the condition. This article assesses such a strategy by employing the standard framework used when evaluating any screening policy. This approach highlights a number of concerns and allows recommendations to help optimize the success of such a strategy if it were to be implemented.