Effect of Hydration on Pulmonary Function and Development of Exercise-Induced Bronchoconstriction among Professional Male Cyclists

ckground: Exercise-induced bronchoconstriction (EIB) is a common problem in elite athletes. Classical pathways in the development of EIB include the osmotic and thermal theory as well as the presence of epithelial injury in the airway, with local water loss being the main trigger of EIB. This study aimed to investigate the effects of systemic hydration on pulmonary function and to

Abstract:Background: Exercise-induced bronchoconstriction (EIB) is a common problem in elite athletes. Classical pathways in the development of EIB include the osmotic and thermal theory as well as the presence of epithelial injury in the airway, with local water loss being the main trigger of EIB. This study aimed to investigate the effects of systemic hydration on pulmonary function and to establish whether it can reverse dehydration-induced alterations in pulmonary function. Materials and Methods: This follow-up study was performed among professional cyclists, without a history of asthma and/or atopy. Anthropometric characteristics were recorded for all participants, and the training age was determined. In addition, pulmonary function tests and speci c markers such as fractional exhaled nitric oxide (FeNO) and immunoglobulin E (IgE) were measured. All the athletes underwent body composition analysis and cardiopulmonary exercise testing (CPET). After CPET, spirometry was followed at the 3rd, 5th, 10th, 15th, and 30th min. This study was divided into two phases: before and after hydration. Cyclists, who experienced a decrease in Forced Expiratory Volume in one second (FEV 1) 10% and/or Maximal Mild-Expiratory Flow Rate (MEF 25–75) 20% after CPET in relation to the results of the spirometry before CPET, repeated the test in 15-20 days, following instructions for hydration. Results: One hundred male cyclists (n= 100) participated in Phase A. After exercise, there was a decrease in all spirometric parameters (p< 0.001). In Phase B, after hydration, in all comparisons, the changes in spirometric values were signi cantly lower than those in Phase A (p< 0.001). Conclusions: The ndings of this study suggest that professional cyclists have non-bene cial effects on respiratory function. Additionally, we found that systemic hydration has a positive effect on spirometry in cyclists. Of particular interest are small airways, which appear to be affected independently or in combination with the decrease in FEV 1. Our data suggest that pulmonary function improves systemic after hydration. Adv. Respir. Med.2023,91, 239–253.

Adv. Respir. Med.2023,91 240 Keywords: exercise-induced bronchoconstriction; elite athletes; pulmonary function tests; hydration; exercise-induced dehydration; exercise-induced airway injury 1. Introduction 1.1. Exercise-Induced Bronchoconstriction Exercise-induced bronchoconstriction (EIB) is de ned as the transient airway contrac- tion after intense exercise without a history of bronchial asthma [1,2]. Exercise is a common EIB trigger in elite athletes and can lead to potential limitations in theirperformance [2–6]. Exercise-induced bronchoconstriction in athletes has unusual clinical characteristics; there- fore, some investigators believe that it is a different asthma phenotype [6]. Many elite athletes with EIB have no history of asthma, suggesting that environmental factors are independently more signi cant than genetic factors in these cases. Environmental factors may have an additional effect on the genetic predisposition to develop bronchoconstriction as well as being independent and signi cant etiological factors [2]. Many specialists have proposed the designation of EIB with asthma (EIBA—bronchoconstriction after exercise in asthmatic athletes) and EIB without asthma (EIBWA—bronchoconstriction triggered by exercise in athletes without other symptoms of asthma) [2,7]. For the aims of this study, EIBWAis referred to as EIB. The prevalence of EIB is 20% to 50% in elite athletes, especially those engaged in high-intensity aerobic exercise [2,8]. The main stimuli for the appearance of EIB are hyperventilation [9] and a hyperosmotic environment on the airway surface [10]. In elite athletes, extreme ventilation conditions cause airway epithelial injuries with the release of special mediators that trigger EIB [1,11–13]. Some studies suggest that long-term and high-intensity training in endurance sports may not only stimulate EIB but also the subsequent appearance of bronchial hyperreactivity outside exercise conditions or perma- nent airway remodeling [14–16]. The epithelium of small airways seems to be the most affected by injury and repair, as shown in mouse studies [6]. 1.2. Hydration and Pulmonary Function Systemic dehydration commonly occurs in athletes who perform sustained physical activity [17]. Even at mild levels (i.e., 2–3% body mass loss [18]), systemic dehydration can have unfavorable effects on multiple organ systems [19]. Limited and contradictory data currently exist regarding the effects of systemic dehydration on the respiratory system and the development of EIB in

1.2. Hydration and Pulmonary Function Systemic dehydration commonly occurs in athletes who perform sustained physical activity [17]. Even at mild levels (i.e., 2–3% body mass loss [18]), systemic dehydration can have unfavorable effects on multiple organ systems [19]. Limited and contradictory data currently exist regarding the effects of systemic dehydration on the respiratory system and the development of EIB in elite athletes. Previous studies showed harmful alterations in expiratory ow or lung volume in healthy populations [20] and in athletes with asthma [21] following mild systemic dehydration. However, there is another study [22] which showed improvements in pulmonary function in healthy adults following moderate dehydration (4.5% body mass loss). The uid supply to the airways stems primarily from bronchial circulation [23]. Op- timal lung uid balance is a critical component of normal pulmonary function [24], with bronchial tree surface liquid dehydration implicated in several respiratory diseases, such as EIB [25]. Water ows across bronchial epithelium in response to osmotic gradient. Whole-body dehydration leads to bronchial blood ow and/or compositional changes, which may compromise airway hydration. Alterations in airway surface liquid thickness, composition, and/or rheology can promote airway instability and provoke premature airway closure [26]. 1.3. Cycling Cycling is recognized as one of the most challenging endurance sporting events worldwide [27,28]. Competitive cycling is highly stressful for both aerobic and anaero- bic metabolisms. A professional cyclist can be de ned as a cyclist who performs high training volumes (~32,500 km) during the competitive season, which includes 90–100 race days [27,28]. Indeed, professional cyclists are often considered to represent the «elite» and

Adv. Respir. Med.2023,91 241 typically demonstrate advanced cardiorespiratory capacity [27,28]. It is now recognized that cycling places signi cant demands on the respiratory system [29,30] during periods of maximal intensity exercise, which can elicit ventilation rates > 150 L/min [31]. In addition to the stress of sustained hyperventilation, elite cyclists are regularly exposed to variable environmental conditions (i.e., uctuations in temperature and humidity), aeroallergens, and particles resulting from the combustion that occurs in the engines. It has been argued that this type of endurance exercise may result in airway changes [10] and has been recog- nized to occur in up to one in ve elite endurance athletes and is prominent in competitive cyclists [32,33]. Many professional cyclists often report a heightened perception of breathlessness, end-race cough, and the sensation that they have «smaller lungs» during or following cycling competition. One study supports the deterioration in lung function and presents troublesome respiratory symptoms following endurance sporting events [34]. This study aimed to examine evidence of EIB in triathletes and assess whether changes in FEV1 were related to respiratory symptoms, training volume, and race time. Lung function was measured before the race, 8–10 min after the race (post-test 1), and the day after the race (post-test 2). Respiratory symptoms and training volume were recorded using a questionnaire. Twenty-six participants (46%) presented with EIB at post-test 1 and16 (28%) at post-test 2. The lung function variables were signi cantly reduced from baseline to post-tests 1 and 2. Changes in FEV1did not correlate with weekly training hours or race. In addition, a weak correlation was observed between the maximal reduction in FEV1and respiratory symptoms, which may affect athletic performance and limit exercise tolerance. In line with the ndings of a study in asthmatic athletes [21,35], we hypothesized that during or immediately after exercise, pulmonary function would be affected in professional cyclists without asthma and that whole-body hydration can improve and restore lung function. This study aimed to investigate the effects of whole-body hydration on pul- monary function and to establish whether it can reverse dehydration-induced alterations in pulmonary function and the development of EIB

[21,35], we hypothesized that during or immediately after exercise, pulmonary function would be affected in professional cyclists without asthma and that whole-body hydration can improve and restore lung function. This study aimed to investigate the effects of whole-body hydration on pul- monary function and to establish whether it can reverse dehydration-induced alterations in pulmonary function and the development of EIB in professional cyclists. 2. Materials and Methods One hundred professional male cyclists (n= 100) were invited to participate in this follow-up study (cohort study). All cyclists were accustomed to cycling for more than 15 hper week in sessions lasting at least 3 to 4 h. They were asked not to drink caffeine or consume alcohol during the sessions of the study, not to exercise 48 h before a session, and arrive at the laboratory between 9:00 am and 2:00 pm. The laboratory has a portable air puri cation system (Health-Way Deluxe, DFS Technology—VOC Filter, New York, NY, USA). The study protocol was approved by the ethics committee of Creta Inter Clinic General Hospital (Registry number: 129/16-09-2020). All participants provided written informed consent in accordance with the Helsinki Declaration and personal data according to the European Parliament and Council of the European Union. This study took place from October 2020 to January 2021. The Inclusion criteria were as follows: absence of a history of bronchial asthma as evidenced by the medical history and pulmonary function tests, normal heart ultrasound, and the training age (>3 years) in the sport. Exclusion criteria were: Female professional cyclists, COVID-19 infection, age (18 < age > 35 years), smoking habits, craniofacial and upper airway deformities (high probability of misapplication of the ergospirometry face mask), having an injury for the last 12 months, anemia (Hb < 13.5 g/dL), upper and lower respiratory system seasonal allergies, high levels of FeNO (>25 ppb), and high levels of IgE (>100 UI/mL). The cause of female exclusion from the study is the known physiological differences between the sexes, speci cally regarding reproductive endocrinology, menstrual cycle, and hormonal contraceptive use.

g/dL), upper and lower respiratory system seasonal allergies, high levels of FeNO (>25 ppb), and high levels of IgE (>100 UI/mL). The cause of female exclusion from the study is the known physiological differences between the sexes, speci cally regarding reproductive endocrinology, menstrual cycle, and hormonal contraceptive use.

Adv. Respir. Med.2023,91 242 2.1. Procedures A detailed history of known medical conditions, current medications, and smoking habits was routinely obtained from all athletes. All cyclists were free from respiratory tract infection two weeks before study entry. In addition, a clinical examination was performed on all participants, which included the following: recording of demographic (sex, age) and anthropometric characteristics such as height, body mass, and Body Mass Index (BMI) [36–38], and determination of training age. Pulmonary function was assessed [39], and speci c markers such as FeNO and IgE, were measured. Finally, the athletes underwent body composition analysis [38], and a cardiopulmonary exercise test (CPET) [40]. With the completion of CPET, spirometry was followed at the 3rd, 5th,10th, 15th, and 30th min. Athletes, who experienced a decrease in FEV1and/or MEF25–75in spirometry after CPET in relation to the results of the spirometry before CPET, re-underwent in 15–20 days, following instructions for uid intake, and the results were correlated with the hydration level. 2.2. Spirometry Lung function was assessed according to the ATS/ERS guidelines [39] on a spirometer (Ergocard Clinical with ExpAir Software, Medisoft Group, Namur, Belgium), and the following parameters were recorded: Forced Vital Capacity (FVC), FEV1, and MEF25–75. Spirometry was performed in a quiet and comfortable environment. Measurements were conducted by the same operator, in the morning. The subject was seated, with shoulders slightly back and, the chin slightly elevated, and a nose clip was used. There were four distinct phases of the FVC maneuver: (1) maximal inspiration, (2) a blast of expiration, (3) continued complete expiration [the expiration stops when a plateau has been reached or the forced expiratory time (FET) reaches 15 s, and (4) inspiration for a maximal ow back to maximum lung volume. The subject inserted a mouthpiece and was instructed to breathe normally or easily. For each pulmonary function test, the best three of all performed measurements, that met the ATS/ERS criteria were evaluated. The largest one was retained to calculate the spirometric values. A decrease in FEV1 10% and/or MEF25–75 20% in spirometry was considered a minimal clinically signi cant difference [8,41]. 2.3. Airway

a mouthpiece and was instructed to breathe normally or easily. For each pulmonary function test, the best three of all performed measurements, that met the ATS/ERS criteria were evaluated. The largest one was retained to calculate the spirometric values. A decrease in FEV1 10% and/or MEF25–75 20% in spirometry was considered a minimal clinically signi cant difference [8,41]. 2.3. Airway In ammation Airway in ammation was assessed by measuring FeNO using a speci c breath ana- lyzer (FeNO Breath Analyzer, Bedfont Scienti c Co., Maidstone, UK) and evaluated against established thresholds: normal < 25 ppb, intermediate: 26–50 ppb, high > 50 ppb [42]. All measurements were performed by the same operator in the morning and before spirometry (spirometric maneuvers reduce FeNO levels). The subject was seated comfortably, and a mouthpiece was used. The participant inhaled over 2 to 3 s through the mouth to total lung capacity and then exhaled immediately. The resultant mouthpiece pressure was at least 5 cmH2O; therefore, contamination of expiration with nasal FeNO was excluded. A ow rate of 0.05 L/s was chosen for all participants. 2.4. Body Hydration Status Hydration status was assessed by total body water percentage (TBW%) using whole- body bioelectrical impedance analysis (BIA) and changes in plasma osmolality (Posm) of the capillary blood. Total body composition was measured with whole-body BIA using four-pole multifrequency equipment (Tanita BC-613S Fat Meter Scale) using a standard technique [43]. The measurement was conducted by the same operator in the morning at temperatures ranging from 24 to 26 C. Simultaneously, capillary blood samples were collected from the participant's ngertips to assess Posm. The samples were analyzed immediately after collection. Posmwas analyzed using freezing point depression osmometry (Advanced ® model 3320 micro-osmometer, Norwood, MA, USA). The subjects were free to have their habitual breakfast three hours before the measurement and should not have exercised 24 h before or consumed alcohol 12 h and water 1 h before the measurements. For the purposes of this study, TBW (%) will be referred to as hydration (%).

free to have their habitual breakfast three hours before the measurement and should not have exercised 24 h before or consumed alcohol 12 h and water 1 h before the measurements. For the purposes of this study, TBW (%) will be referred to as hydration (%).

Adv. Respir. Med.2023,91 243 2.5. Anthropometric Characteristics Body mass (kg) and height (cm) were measured according to the manual reference for anthropometric standardization [44]. All the subjects wore light clothing and were barefoot. Body mass index (BMI) was calculated by dividing the body mass (kg) by the squared height (m) [BMI = Body mass (kg)/height (m) 2 ] (Table). Table 1. Descriptive statistics of age, training age, and somatometric variables. Data are expressed as percent, mean SD. Mean SD m (IQR) Min–Max Age years 27.0 5.0 30 (22–33) 18–34 Training age years 12.0 5.0 14 (7–17) 3–19 Height cm 177 5 178 (174–182) 167–187 Body mass kg 74.7 5.2 74.6 (72–78) 64–85 BMI kg/m 2 23.8 1.4 23.6 (22.6–24.4) 21.5–26.8 Body fat % 11.6 1.0 11.7 (11–12.4) 11.3–13.1 Hydration % 53.0 7.0 53.0 (46.0–58.0) 41.0–69.0 Posm mosm kg 1 283 2.4 281 (279–286) 278–288 2.6. Systemic Hydration Protocol Athletes performed two exercise sessions: exercise without uid intake and exercise accompanied by hydration with water. In every session, the participants exercised until exhaustion. During the rst session, the protocol for all the participants was exercised without uid intake. The time elapsed between the exercise sessions was two weeks. During the two weeks, the cyclists were instructed to drink no less than 3 L of uid daily (without alcohol), regardless of whether they had an easy or hard training session or a recovery day. There was a phone recall to the subjects every 4 days concerning their adherence to the consumption of 3 L daily. During the second session, all participants were hydrated by a standard hydration protocol before exercise, which included ingesting water at room temperature, mixed with 3 gr NaCl in 1 lit H2O to improve uid retention [45]. The participants gradually consumed 300 mL of water 120 min before exercise, 300 mL 60 min before exercise, and another 600 mL 30 min before exercise. 2.7. Cardiopulmonary Exercise Test (CPET) In this study, CPET was performed using a cycloergometer (Ergocard Clinical with ExpAir Software, Medisoft Group, Namur, Belgium). The CPET protocol consisted of the following procedure: it started with a

participants gradually consumed 300 mL of water 120 min before exercise, 300 mL 60 min before exercise, and another 600 mL 30 min before exercise. 2.7. Cardiopulmonary Exercise Test (CPET) In this study, CPET was performed using a cycloergometer (Ergocard Clinical with ExpAir Software, Medisoft Group, Namur, Belgium). The CPET protocol consisted of the following procedure: it started with a two-minute rest period, followed by one minute of warm-up pedaling against a minimal load of 20 watts, progressively increasing by 50 watts per three minutes. Environmental indoor conditions during the exercise sessions were kept constant, with a temperature of 24–26 C, and relative humidity of 45–50%. Participants wore sports clothes commonly used in cycling and were free to have their habitual breakfast 3 h before the exercise session. Participants were asked not to exercise 24 h prior to a session and arrive at the laboratory between 9:00 a.m. and 2:00 p.m. On the rst visit, they were given 15 min to adapt to the stationary bicycle of the laboratory. The duration of the test was until exhaustion. CPET was conducted under continuous monitoring of heart rate (HR), 12-lead electrocardiogram (ECG), and pulse oxygen saturation (SpO2), while systolic and diastolic blood pressure was recorded every two minutes with a cuff sphygmomanometer. Indications for early test termination included myocardial ischemia, complex ventricular premature beats, grade-2 or grade-3 atrioventricular block, a sudden fall in blood pressure level, by more than 20 mmHg, and elevated blood pressure (>220/120 mmHg) [2,46]. 2.8. Statistical Analysis Continuous variables were expressed in the form of mean Standard Deviation (SD), while the median (m), interquartile ranges (IQS), and range (min–max) were also used in some cases. Categorical variables are expressed as counts and percentages. For continuous

The study examines hydration's impact on pulmonary function in professional male cyclists.