Julie Stang

Two distinct phenotypes of asthma in elite athletes identified by latent class analysis

Abstract Introduction: Clusters of asthma in athletes have been insufficiently studied. Therefore, the present study aimed to characterize asthma phenotypes in elite athletes using latent class analysis (LCA) and to evaluate its association with the type of sport practiced. Methods: In the present cross-sectional study, an analysis of athletes’ records was carried out in databases of the Portuguese National Anti-Doping Committee and the Norwegian School of Sport Sciences. Athletes with asthma, diagnosed according to criteria given by the International Olympic Committee, were included for LCA. Sports practiced were categorized into water, winter and other sports. Results: Of 324 files screened, 150 files belonged to asthmatic athletes (91 Portuguese; 59 Norwegian). LCA retrieved two clusters: “atopic asthma” defined by allergic sensitization, rhinitis and allergic co-morbidities and increased exhaled nitric oxide levels; and “sports asthma”, defined by exercise-induced respiratory symptoms and airway hyperesponsiveness without allergic features. The risk of developing the phenotype “sports asthma” was significantly increased in athletes practicing water (OR = 2.87; 95%CI [1.82–4.51]) and winter (OR = 8.65; 95%CI [2.67–28.03]) sports, when compared with other athletes. Conclusion: Two asthma phenotypes were identified in elite athletes: “atopic asthma” and “sports asthma”. The type of sport practiced was associated with different phenotypes: water and winter sport athletes had three- and ninefold increased risk of “sports asthma”. Recognizing different phenotypes is clinically relevant as it would lead to distinct targeted treatments.

Parasympathetic activity and bronchial hyperresponsiveness in athletes

PURPOSE A high prevalence of asthma and bronchial hyperresponsiveness (BHR) is reported in swimmers and cross-country skiers. It has been suggested that increased parasympathetic nervous activity is involved in asthma development in endurance athletes. We aimed to assess the associations of BHR to parasympathetic activity in healthy and asthmatic swimmers and cross-country skiers and healthy nonathletes. METHODS Parasympathetic activity was measured by pupillometry and heart rate variability at the onset of exercise with the cardiac vagal index calculated in 28 cross-country skiers (♂18/♀10), 29 swimmers (♂17/♀12), and 30 healthy nonathlete controls (♂14/♀16) on two different days. All subjects performed a methacholine bronchial challenge with the provocation dose causing 20% decrease in the forced expiratory volume in 1 s calculated (PD20met). Data were analyzed by robust regression analysis and presented as β coefficients with 95% confidence intervals (CI). RESULTS PD20met was negatively associated with cardiac vagal index (-13.9, 95% CI = -26.8 to -1.0) in all subjects. When adjusted to the type of sport, this association was stronger in swimmers (-8.3, 95% CI = -13.0 to -3.6) as compared with controls and nonsignificant in cross-country skiers. Percent pupil constriction was significantly associated with PD20met in swimmers (-9.4, 95% CI = -15.4 to -3.4) only after adjusting for the type of sport. Fourteen swimmers (48%) and 16 cross-country skiers (57%) had doctor-diagnosed asthma in combination with current BHR and/or current use of asthma drugs. Seventy-two percent swimmers, 44% cross-country skiers, and 39% controls had a PD20met ≤8 μmol (P = 0.015). Fourteen swimmers had a PD20met ≤2 μmol as compared with one cross-country skier (P < 0.001). CONCLUSION Parasympathetic activity measured in the heart is more closely related to BHR as compared with parasympathetic activity measured in the pupils. The type of sport influences BHR severity and its relationship to parasympathetic activity.

Increased bronchial parasympathetic tone in elite cross-country and biathlon skiers: a randomised crossover study

This article has been retracted.

Exhaled nitric oxide concentration upon acute exposure to moderate altitude.

The purpose of this study was to assess immediate changes in the partial pressure of nitric oxide (NO) in exhaled gas (PENO) in healthy trained subjects who were acutely exposed to moderate altitude. One group of nine and another group of 20 healthy subjects were exposed to an ambient pressure of 728 hPa (546 mmHg) corresponding to an altitude of 2800 m for 5 and 90 min, respectively, in an altitude chamber. PENO was measured offline by sampling exhaled gas in tight metal foil bags at 5, 30, 60, and 90 min. A correction for increased expiratory flow rate due to gas density effects at altitude was performed (PENOcorr). PENO was significantly decreased by 13–16%, while the fraction of NO in exhaled gas (FENO) was increased by 16–19% compared to sea level. There was no significant change in PENOcorr after exposure to altitude for 5, 30, 60, and 90 min. We conclude that there was no change in PENO upon arrival at altitude after correcting for gas density effects on expiratory flow rate. Corrections for altitude effects must be done before comparing measurements performed at different altitudes when using measurements of FENO to monitor athletes who have asthma during training at altitude.

Assessment of Parasympathetic Activity in Athletes: Comparing Two Different Methods.

INTRODUCTION A variety of methods are used to assess parasympathetic activity in athletes targeting different organs; however, the reliability of or interchangeability between measurement procedures is not clear. OBJECTIVE The purpose of this study is to identify the repeatability of two parasympathetic activity measurement procedures, the HR variability during a 4-s exercise test (4sET), and the contractile properties of the pupil (pupillometry), and to assess their agreement. The secondary objective of this study is to assess their relationship with the bronchodilating effect of inhaled ipratropium bromide (iIB), blocking parasympathetic signals to the lungs. METHODS Forty athletic subjects were enrolled in a cross-sectional study. After 15-min resting in semidarkness, subjects underwent pupillometry (PLR-200™, NeurOptics Inc., CA), followed by 4sET on a cycle ergometer. HR variability was assessed by Polar Electro® HR monitor (RS-800CX/G3; Oy, Kempele, Finland). Both protocols were repeated after 5 min. Statistical analysis was performed according to Bland and Altman and by using Pearsons correlation coefficient and intraclass correlation. Lung function measurements by flow volume curves were performed before and 45 min after iIB. RESULTS The means of differences were 1.21% (limits of agreement, -3.59 to 6.02) for pupil constriction and 0.05 mm (-0.28 to 0.39) for pupil amplitude. The mean of differences for 4sET was 0.005 (-0.31 to 0.32). A very weak intraclass correlation (r = -0.01, P = 0.58) showed no agreement between the methods. No correlation was observed between pupillometry variables or 4sET with the change in lung function after iIB. CONCLUSION Pupillometry showed better repeatability compared with the 4sET. There is poor agreement between parasympathetic activity levels measured in three different target organs of athletic subjects; the heart, the pupil, and the lung. Thus, methods assessing parasympathetic activity in different target organs cannot be used interchangeably.

Exhaled nitric oxide concentration in the period of 60 min after submaximal exercise in the cold.

Fractional expired nitric oxide (FENO) is decreased after exercise. The effect of exercise in the cold upon FENO is unknown.

Exhaled nitric oxide after high-intensity exercise at 2800 m altitude

Nitric oxide (NO) concentration in exhaled gas is a marker of some inflammatory processes in the lung, and endogenous NO plays a role in the physiological responses to exercise and altitude. The aim of this study was to compare changes in exhaled NO concentration 5–60 mins after high‐intensity exercise at 2800 m and at 180 m altitude.

Voluntary Movement Frequencies in Submaximal One- and Two-Legged Knee Extension Exercise and Pedaling

Understanding of behavior and control of human voluntary rhythmic stereotyped leg movements is useful in work to improve performance, function, and rehabilitation of exercising, healthy, and injured humans. The present study aimed at adding to the existing understanding within this field. To pursue the aim, correlations between freely chosen movement frequencies in relatively simple, single-joint, one- and two-legged knee extension exercise were investigated. The same was done for more complex, multiple-joint, one- and two-legged pedaling. These particular activities were chosen because they could be considered related to some extent, as they shared a key aspect of knee extension, and because they at the same time were different. The activities were performed at submaximal intensities, by healthy individuals (n = 16, thereof eight women; 23.4 ± 2.7 years; 1.70 ± 0.11 m; 68.6 ± 11.2 kg). High and fair correlations (R-values of 0.99 and 0.75) occurred between frequencies generated with the dominant leg and the nondominant leg during knee extension exercise and pedaling, respectively. Fair to high correlations (R-values between 0.71 and 0.95) occurred between frequencies performed with each of the two legs in an activity, and the two-legged frequency performed in the same type of activity. In general, the correlations were higher for knee extension exercise than for pedaling. Correlations between knee extension and pedaling frequencies were of modest occurrence. The correlations between movement frequencies generated separately by each of the legs might be interpreted to support the following working hypothesis, which was based on existing literature. It is likely that involved central pattern generators (CPGs) of the two legs share a common frequency generator or that separate frequency generators of each leg are attuned via interneuronal connections. Further, activity type appeared to be relevant. Thus, the apparent common rhythmogenesis for the two legs appeared to be stronger for the relatively simple single-joint activity of knee extension exercise as compared to the more complex multi-joint activity of pedaling. Finally, it appeared that the shared aspect of knee extension in the related types of activities of knee extension exercise and pedaling was insufficient to cause obvious correlations between generated movement frequencies in the two types of activities.

The Role of Airway Inflammation and Bronchial Hyperresponsiveness in Athlete's Asthma

Purpose Asthma is frequently reported in endurance athletes. The aim of the present study was to assess the long-term airway inflammatory response to endurance exercise in high-level athletes with and without asthma. Methods In a cross-sectional design, 20 asthmatic athletes (10 swimmers and 10 cross-country skiers), 19 athletes without asthma (10 swimmers and 9 cross-country skiers), and 24 healthy nonathletes completed methacholine bronchial challenge, lung function tests, and sputum induction on two separate days. All athletes competed on a national or international level and exercised ≥10 h·wk−1. The nonathletes exercised ⩽5 h·wk−1 and reported no previous lung disease. Bronchial hyperresponsiveness (BHR) was defined as a methacholine provocation dose causing 20% decrease in the forced expiratory volume in 1 s of ⩽8 &mgr;mol. Results BHR was present in 13 asthmatic athletes (62%), 11 healthy athletes (58%), and 8 healthy nonathletes (32%), and the prevalence differed among groups (P = 0.005). Sputum inflammatory and epithelial cell counts did not differ between groups and were within the normal range. Median (25th to 75th percentiles) sputum interleukin-8 was elevated in both asthmatic (378.4 [167.0–1123.4]) and healthy (340.2 [175.5–892.4]) athletes as compared with healthy nonathletes (216.6 [129.5–314.0], P = 0.02). No correlations were found between provocation dose causing 20% decrease and sputum cell counts. Conclusion Independent of asthma diagnosis, a high occurrence of BHR and an increased sputum interleukin-8 were found in athletes as compared with nonathletes. Airway inflammation or epithelial damage was not related to BHR.