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Maximal exercise capacity is reduced at altitude or during hypoxia at sea level. It has been suggested that this might reflect increased right ventricular afterload due to hypoxic pulmonary vasoconstriction. We have shown previously that the pulmonary vascular sensitivity to hypoxia is enhanced by sustained isocapnic hypoxia, and inhibited by intravenous iron. In this study, we tested the hypothesis that elevated pulmonary artery pressure contributes to exercise limitation during acute hypoxia. Twelve healthy volunteers performed incremental exercise tests to exhaustion breathing 12% oxygen, before and after sustained (8-h) isocapnic hypoxia at sea level. Intravenous iron sucrose (n = 6) or saline placebo (n = 6) was administered immediately before the sustained hypoxia. In the placebo group, there was a substantial (12.6 ± 1.5 mmHg) rise in systolic pulmonary artery pressure (SPAP) during sustained hypoxia, but no associated fall in maximal exercise capacity breathing 12% oxygen. In the iron group, the rise in SPAP during sustained hypoxia was markedly reduced (3.4 ± 1.0 mmHg). There was a small rise in maximal exercise capacity following sustained hypoxia within the iron group, but no overall effect of iron, compared with saline. These results do not support the hypothesis that elevated SPAP inhibits maximal exercise capacity during acute hypoxia in healthy volunteers.

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Bakgrund Ansträngningsutlöst bronkkonstriktion (EIB) innebär en övergående luftvägsobstruktion i samband med ansträngning och definieras som en minskning med ≥ 10% av den forcerade utandningen under första sekunden (FEV1). EIB är vanligt bland elitskidåkare. Referenstestet för diagnostik är torrluftsprovokation men ansträngningstest (ECT) i fält anses ha högre representativitet och sensitivitet men är svårt att standardisera. ECT i köldkammare kombinerar en idrottspecifik provokation med en standardiserad miljö men har aldrig använts för att undersöka förekomsten av EIB bland vinteridrottare. Målet med studien var att kartlägga prevalensen av EIB hos elitskidåkare med hjälp av ECT i kyla. Material och metod De 31 deltagarna (16 kvinnor) var ett slumpmässigt urval av de 174 längdskidåkare och skidskyttar från Sveriges riksidrottsgymnasium och nationella idrottsutbildningar som vintern 2022 deltog i en web-enkät om luftvägssymtom, träning och astma. Sex (19%) deltagare hade använt astmamediciner för en läkardiagnostiserad astma de senaste 12 månaderna. ECT i en köldkammare utfördes (8 min löpning i -14,7 °C, Rh 77% på 85% av beräknad maxpuls) med spirometri före och 5-30 minuter efter. Resultat EIB detekterades hos 7 (23%) av deltagarna, 5 av 25 utan astma och 2 av 6 med astma. En deltagare sjönk >15% på FEV1 och hade ingen tidigare känd astma. Kön, ålder, träningstimmar, allergi, FeNO och förekomst av pip/väs från luftvägarna med andnöd de senaste 12 månaderna skiljde sig inte åt mellan deltagarna med och utan EIB. Slutsats ECT i kyla påvisar en hög förekomst av EIB hos unga, friska, svenska elitskidåkare, redan tidigt i karriären och oavsett tidigare känd astma. Att förekomsten av EIB hos skidåkarna med astma inte var högre skulle kunna vara ett resultat av deras antiinflammatoriska astmaläkemedel eller överdiagnostik.

Background and Aims: Winter endurance athletes have a high prevalence of exercise-induced bronchoconstriction (EIB) and asthma, probably due to repeated and prolonged inhalation of cold and dry air. Heat- and moisture-exchanging devices (HME) warm and humidify inhaled air and prevent EIB. The aim of this study was to share cross-country skiers and biathletes' experiences of training and competition in low temperatures, views on temperature limits, usage of HME, and consequences of cold exposure on their health. Methods: Eleven Swedish World Championship or Olympic medalists in cross-country skiing and biathlon were interviewed and transcripts were analyzed using qualitative content analysis. Results: Participants described how cold temperatures predominantly affected the airways, face, and extremities. During training, extreme cold was managed by choosing warmer clothing, modification of planned sessions, use of HME, delaying training, or changing location. In competition, participants described limited possibility for such choices and would prefer adjustment of existing rules (i.e., more conservative temperature limits), especially since they understood elite skiing in low temperatures to present an occupational hazard to their health. Participants had at times used HMEs during training in cold environments but described mixed motives for their use—that HMEs warm and humidify cold inhaled air but introduce additional resistance to breathing and can cause problems due to mucus and ice build-up. Skiers also perceived that they had become more sensitive to cold during the latter part of their careers. Conclusions: The present study gives a unique insight into the “cold” reality of being an elite athlete in skiing and biathlon. Cold exposure results in negative health consequences that are preventable, which means that rules must be followed, and organizers should acknowledge responsibility in protecting athletes from occupational hazards. Development of evidence-based

Purpose The aim of this study was to investigate within-cycle differences in nocturnal heart rate (HR) and heart rate variability (HRV) in naturally menstruating women (NM) and women using combined hormonal contraceptives (CU) or progestin-only hormonal contraceptives (PU). Methods Physically active participants were recruited into three groups: NM (n = 19), CU (n = 11), and PU (n = 12). Participants’ HR and HRV (with Bodyguard 2 HRV monitor), and blood hormones were monitored during one menstrual cycle (MC) (NM-group) or for 4 weeks (CU and PU-groups). Estradiol, progesterone, and luteinizing hormone were analyzed from fasting blood samples collected four times in the NM (M1 = bleeding, M2 = follicular phase, M3 = ovulation, and M4 = luteal phase) and PU groups (M1 = lowest E2; M2 = M1 + 7 days; M3 = M1 + 14 days; M4 = M1 + 21 days) and twice in the CU group (active and inactive pill phases). After every blood sample, nightly HR and HRV were recorded and examined as an average from two nights. Results Hormonal concentrations differed (p < 0.05) between MC phases in the NM- and PU-groups, but not (p ≥ 0.116) between the active and inactive phases in the CU-group. In the NM- and PU-groups, some of the HRV values were higher, while in the NM-group, HR was lower during M2 compared to M3 (p < 0.049) and M4 (p < 0.035). In the CU-group, HRV values (p = 0.014-0.038) were higher, and HR was lower (p = 0.038) in the inactive phase compared to the first week of the active phase. Conclusions The MC and hormonal cycle phases influence autonomic nervous system balance, which is reflected in measurements of nocturnal HR and HRV. This should be considered when monitoring recovery in physically active individuals.

The aim of this study was to investigate effects of a single infrared sauna (IRS) session on postexercise recovery of neuromuscular performance, autonomic nervous system function, subjective sleep quality, and muscle soreness. Male basketball players (n = 16) performed two trials consisting of a complex resistance exercise protocol (maximal strength with plyometrics), followed by either 20 min passive recovery (PAS) or IRS (temperature 43±5°C), in a randomized crossover design, with trials separated by one week. Recovery of neuromuscular performance was assessed using 20 m maximal sprint, maximal countermovement-jump (CMJ), and isometric leg press tests, performed 14 hours after exercise. Heart rate (HR), heart rate variability (HRV), sleep diary, muscle soreness, and indirect muscle damage markers were measured pre and post exercise. The decrease in CMJ performance from pre- to post-exercise was attenuated after IRS compared to PAS (p < 0.01). The IRS session resulted in higher HR and lower root mean square of successive differences between normal heartbeats (RMSSD), and high and low frequency power, compared to PAS (p < 0.002). Post-exercise night-time HR and HRV did not differ following IRS vs. PAS. Muscle soreness was less severe, and perceived recovery was higher after IRS compared to PAS (p < 0.01). Post-exercise IRS attenuated the drop in explosive performance and decreased subjective muscle soreness after resistance training, which may enhance mood, readiness, and physical performance of an athlete. A single IRS session had no detrimental effects on recovery of the autonomic nervous system.

Purpose: Exposure to cold air may harm the airways. It is unclear to what extent heavy exercise adds to the cold-induced effects on peripheral airways, airway epithelium, and systemic immunity among healthy individuals. We investigated acute effects of heavy exercise in sub-zero temperatures on the healthy airways. Methods: Twenty-nine healthy individuals underwent whole body exposures to cold air in an environmental chamber at − 15 °C for 50 min on two occasions; a 35-min exercise protocol consisting of a 5-min warm-up followed by 2 × 15 min of running at 85% of VO2max vs. 50 min at rest. Lung function was measured by impulse oscillometry (IOS) and spirometry before and immediately after exposures. CC16 in plasma and urine, and cytokines in plasma were measured before and 60 min after exposures. Symptoms were surveyed pre-, during and post-trials. Results: FEV1 decreased after rest (− 0.10 ± 0.03 L, p < 0.001) and after exercise (− 0.06 ± 0.02 L, p = 0.012), with no difference between trials. Exercise in − 15 °C induced greater increases in lung reactance (X5; p = 0.023), plasma CC16 (p < 0.001) as well as plasma IL-8 (p < 0.001), compared to rest. Exercise induced more intense symptoms from the lower airways, whereas rest gave rise to more general symptoms. Conclusion: Heavy exercise during cold air exposure at − 15 °C induced signs of an airway constriction to a similar extent as rest in the same environment. However, biochemical signs of airway epithelial stress, cytokine responses, and symptoms from the lower airways were more pronounced after the exercise trial.

Purpose: Exposure to cold air may harm the airways. It is unclear to what extent heavy exercise adds to the cold-induced effects on peripheral airways, airway epithelium, and systemic immunity among healthy individuals. We investigated acute effects of heavy exercise in sub-zero temperatures on the healthy airways. Methods: Twenty-nine healthy individuals underwent whole body exposures to cold air in an environmental chamber at − 15 °C for 50 min on two occasions; a 35-min exercise protocol consisting of a 5-min warm-up followed by 2 × 15 min of running at 85% of VO2max vs. 50 min at rest. Lung function was measured by impulse oscillometry (IOS) and spirometry before and immediately after exposures. CC16 in plasma and urine, and cytokines in plasma were measured before and 60 min after exposures. Symptoms were surveyed pre-, during and post-trials. Results: FEV1 decreased after rest (− 0.10 ± 0.03 L, p < 0.001) and after exercise (− 0.06 ± 0.02 L, p = 0.012), with no difference between trials. Exercise in − 15 °C induced greater increases in lung reactance (X5; p = 0.023), plasma CC16 (p < 0.001) as well as plasma IL-8 (p < 0.001), compared to rest. Exercise induced more intense symptoms from the lower airways, whereas rest gave rise to more general symptoms. Conclusion: Heavy exercise during cold air exposure at − 15 °C induced signs of an airway constriction to a similar extent as rest in the same environment. However, biochemical signs of airway epithelial stress, cytokine responses, and symptoms from the lower airways were more pronounced after the exercise trial.

Training in cold climates is an established risk factor for development of exercise-induced bronchoconstriction and asthma. Inhalation of large volumes of cold and dry air challenges the airways’ capacity to condition inspired air, leading to acute airway injury, and over time, bronchial hyperresponsiveness. We lack evidence-informed guidelines regarding ‘safe’ thresholds for exercise in cold climates, i.e., temperatures (as well as exercise intensities/durations) that do not substantially increase the risk for healthy individuals to develop asthma. This study aimed to investigate the effect of temperature on systemic asthma- and exercise-associated cytokine responses to moderate-intensity exercise among healthy individuals. 31 healthy participants provided written, informed consent to participate in this randomised, crossover trial. On separate days, participants completed a 5 min warm up followed by 30 min running exercise (62-78% VO2peak) in a climate chamber at 10 or -10°C. Blood samples were taken pre and 1 h post-exercise and analysed for 10 cytokines (GM-CSF, IL-10, IL-13, IL-17E, IL-1β, IL-4, IL-5, IL-6, IL-8 and TNF-α) using multiplex ELISA. Values below the lower limit of detection for the assay were excluded. Data from 21 participants were analysed using two-way repeated measures ANOVA. IL-6 and IL-8 increased post-exercise (IL-6: log2 fold change: 0.47±0.67, p=0.001; IL-8: log2 fold change: 0.16±0.27, p=0.001). There were no differences in the response magnitude of any cytokine to exercise in -10 versus 10°C. We conclude that exposure to -10°C does not exacerbate inflammatory responses to moderate-intensity exercise, including for cytokines associated with exercise-induced asthma. This article was presented at the 2022 ERS Lung Science Conference, in session “Poster Session 2”.This is an ERS Lung Science Conference abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS mem

Every year, the European Respiratory Society (ERS) organises the Lung Science Conference (LSC), in Estoril, to discuss basic and translational science. The topic of the 20th LSC was “Mucosal immunology of the lung: balancing protective immunity and chronic inflammation”. This was the first time that the LSC was organised as a hybrid congress with both in person and online attendance. In addition to an outstanding scientific programme, the LSC provides excellent opportunities for career development and inclusion of early career members (ECMs). All scientific and poster sessions are chaired by an ECM who is paired with a senior faculty to allow ECMs to become acquainted with session chairing, and there is a session organised by the Early Career Member Committee (ECMC) dedicated to career development. Moreover, travel bursaries are made available to abstract authors, and all bursary recipients and first-time attendees are invited to take part in a mentorship lunch. In this article, we provide the names of the ECM awardees and describe the scientific highlights of the LSC 2022 for those who could not attend.

Introduction: Every March, dogsled drivers (mushers) compete in a 1569-km race across Alaska, involving physical exertion, mental exertion, and sleep deprivation for up to 2 wk. These factors may increase mushers’ vulnerability to illness, making them a relevant study population for acute infection risk factors. Specifically, the influence of psychological factors on illness risk during prolonged physical exertion has rarely been investigated. The aim of this study was to examine the relationship between psychological characteristics, sleep deprivation, and illness incidence in Iditarod mushers. Methods: Fourteen mushers completed 4 psychological instruments to assess state and trait anxiety, resilience and perceived stress, and self-reported upper respiratory symptoms (URS) in the month before the race. Mushers self-reported sleep duration and URS during the race. Results: State and trait anxiety, resilience, and perceived stress did not differ between mushers with and without pre- and in-race URS (P>0.05). However, all mushers who reported in-race URS had reported URS ≤9 d before the race, and the onset of symptoms during the race typically occurred shortly after a rest period. Sleep duration was higher in mushers who reported in-race URS, both before (4.9±0.3 h, P=0.016) and during illness (5.9±1.3 h, P=0.006), vs mushers without in-race URS (3.4±0.8 h). Conclusions: This study highlights recent illness, rest periods, and greater sleep requirements as potential risk factors for URS onset during a multiday endurance challenge, whereas psychological factors were not associated with URS.

Background: Strenuous exercise in sub-zero environments may cause airway injury and exerciseinduced bronchoconstriction (EIB) (1). Atopic disposition is a risk factor for EIB development (2). However, it is currently unknown whether atopic disposition influences the acute respiratory responses to exercise in a sub-zero climate. Aim: To examine whether the respiratory responses to short- and long-duration exercise at -15⁰C differ between atopic and non-atopic subjects. Methods: Eighteen non-asthmatic, endurance-trained volunteers (males/females: 14/4, age: 29.4 ± 5.9 years old, maximal oxygen consumption (V̇O2max): 61.3 ± 8.7 ml/kg/min) were screened for atopy via the Allergy Questionnaire for Athletes (3) and completed two moderate-intensity (60% V̇O2max) environmental chamber running trials at -15⁰C lasting for 30 and 90 min in a randomized cross-over design. The study was conducted in accordance with the Declaration of Helsinki and was approved by the Swedish Ethical Review Authority. Dynamic spirometry (4) was performed at baseline and 15 and 55 min post-exercise to measure forced expiratory volume in 1 sec (FEV1). Venous blood samples collected pre-exercise and 10 and 65 min post-exercise were analysed for serum Clara cell secretory protein (CC16) using an enzyme-linked immunosorbent assay. A respiratory questionnaire (5) was administered before, immediately after and 20 min after exercise to examine the proportion of affirmative responses (‘YES’) to the occurrence of four symptoms (cough, wheezing, chest tightness and hypersecretion of mucus) associated with lower airways. To examine 2- and 3-way interaction effects on the relative change in FEV1 from baseline as well as the CC16 concentration, a 3-factor repeated measures ANOVA and a linear mixed-effects model were employed, respectively. A twoproportion z-test was performed to compare the symptom frequency between the two groups. Analyses entailing multiple comparisons were adjusted with the Benjamini-Hochber

Heat‐ and moisture exchanging breathing devices (HME) humidify and heat inhaled air and prevent exercise‐induced bronchoconstriction. HMEs have potential as primary preventers against airway damage and asthma induced by exercise in sub‐zero temperatures. HME usage among athletes has not been previously investigated. This study surveyed the usage of and attitudes towards HMEs among elite skiers. We invited all 347 students from Swedish National Elite Sports Schools in cross‐country skiing and biathlon to participate in a web‐survey. The response rate was 55%, 53% were women, 30% had asthma, and 87% were cross‐country skiers. Their mean (range) age was 17 (15‐19) years. HMEs were used often or occasionally by 71% of respondents, while. 68% reported respiratory symptoms while training in sub‐zero temperatures. The most common temperature threshold for using HMEs was −15 °C. Almost all participants believed that HMEs prevent airway problems induced by training in cold. The participants were motivated, and confident in succeeding, to increase their HME usage during exercise in −10 °C or colder, if recommended. Swedish adolescent skiers commonly use HMEs and have positive attitudes towards increased HME usage. HMEs may constitute a simple and effective prevention strategy against airway symptoms and asthma among winter endurance athletes.

Although high and simulated altitude training has become an increasingly popular training method, no study has investigated the influence of acute hypoxic exposure on balance in team-sport athletes. Therefore, the purpose of this study was to investigate whether acute exposure to normobaric hypoxia is detrimental to balance performance in highly-trained basketball players. Nine elite and nine sub-elite male basketball players participated in a randomized, single-blinded, cross-over study. Subjects performed repeated trials of a single-leg balance test (SLBT) in an altitude chamber in normoxia (NOR; approximately sea level) with FiO2 20.9% and PiO2 ranging from 146.7 to 150.4 mmHg and in normobaric hypoxia (HYP; ~3,800 m above sea level) with FiO2 13.0% and PiO2 ranging from 90.9 to 94.6 mmHg. The SLBT was performed three times: 15 min after entering the environmental chamber in NOR or HYP, then two times more interspersed by 3-min rest. Peripheral oxygen saturation (SpO2) and heart rate (HR) were recorded at four time points: after the initial 15-min rest inside the chamber and immediately after each SLBT. Across the cohort, the balance performance was 7.1% better during NOR than HYP (P < 0.01, η2pηp2 = 0.58). However, the performance of the elite group was not impaired by HYP, whereas the sub-elite group performed worse in the HYP condition on both legs (DL: P = 0.02, d = 1.23; NDL: P = 0.01, d = 1.43). SpO2 was lower in HYP than NOR (P < 0.001, η2pηp2 = 0.99) with a significant decline over time during HYP. HR was higher in HYP than NOR (P = 0.04, η2pηp2 = 0.25) with a significant increase over time. Acute exposure to normobaric hypoxia detrimentally affected the balance performance in sub-elite but not elite basketball players.

Exposure to a cold climate is associated with an increased morbidity and mortality, but the specific mechanisms are largely unknown. People with cardiopulmonary disease and winter endurance athletes are particularly vulnerable. This study aimed to map multiple domains of airway responses to exercise in subzero temperature in healthy individuals. Thirty-one healthy subjects underwent whole-body exposures for 50 minutes on two occasions in an environmental chamber with intermittent moderate-intensity exercise in +10 °C and -10 °C. Lung function, plasma/urine CC16 , and symptoms were investigated before and after exposures. Compared to baseline, exercise in -10 °C decreased FEV1 (p=0.002), FEV1/FVC (p<0.001), and increased R20Hz (p=0.016), with no differences between exposures. Reactance increased after +10 °C (p=0.005), which differed (p=0.042) from a blunted response after exercise in -10 °C. Plasma CC16 increased significantly within exposures, without differences between exposures. Exercise in -10 °C elicited more intense symptoms from the upper airways, compared to +10 °C. Symptoms from the lower airways were few and mild. Short-duration moderate-intensity exercise in -10 °C induces mild symptoms from the lower airways, no lung function decrements or enhanced leakage of biomarkers of airway epithelial injury, and no peripheral bronchodilatation, compared to exercise in +10 °C.

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; V˙ O 2peak 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 (fR), and thoracic area skin temperature (Tsk) 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, fR, 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 Tsk was 0.66 °C higher during the HME TT in men. HR (+ 2.7 beats·min−1) and Tsk (+ 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.

INTRODUCTION:Subjective sleep quality may decrease during menstruation, although the duration and composition of sleep remains relatively stable across the menstrual cycle (MC) (1). Recording heart rate variability (HRV) is a tool to monitor the autonomic nervous system and recovery of the body. Meta-analytical data has not revealed significant changes in HRV from the early follicular phase (menses) to the mid-follicular phase (2). However, reduced HRV-values were observed during menses compared to follicular phase in women with pain during menses (dysmenorrhea) (3). Only a few studies have examined effects of the MC on nocturnal HRV. The aim of this study was to investigate how menses and associated pain affects nocturnal HRV and subjective sleep quality.METHODS:Participants included 14 healthy, physically active women, who did not use hormonal contraception. During one MC, participants completed a diary of sleep, MC and related symptoms. HRV was registered every night (Bodyguard 2, Firstbeat Technologies Ltd., Finland). HRV-data (RMSSD and LF/HF-ratio) were analyzed for two nights after a blood sample and over a four-hour period beginning 30 min after bedtime. Only the menses (M) and mid-follicular phases (FP) are used in this study. Blood samples (estradiol, E2, and progesterone, P4) were collected during M (day 2-3 of the MC) and FP (day 7-10) to ensure normal hormonal function associated with the MC (4).RESULTS:E2 was higher (p=0.012) during FP (267±150 pmol/L) compared to M (143±88 pmol/L), but P4 remained stable (p=0.103). Mean heart rate (HRmean) was higher during M (54±8 beats/min) compared to FP (52±7 beats/min, p=0.022). However, HRV-variables did not differ between M and FP (RMSSD: 76.7±34.5 to 77.3±27.0 ms, p=0.872; LF/HF: 1.416±1.380 to 1.273±0.769, p=0.826). Subjectively-assessed sleep quality remained unchanged between M and FP (p=0.349). The change in RMSSD and HRmean between M and FP did not differ (RMSSD: p=0.728; HRmean: p=0.149) between particip

INTRODUCTION: During or shortly after strenuous exercise, some individuals may exhibit exercise-induced bronchoconstriction (EIB) (1). Training in sub-zero temperatures, where the inspired air is cold and dry, can exacerbate the physiological stimuli that give rise to EIB and accentuate lung injury (2). To date, little is known about the training factors, such as duration and modality of exercise that result in airway damage in cold environments. Here, we aimed to examine the influence of exercise duration in cold on lung function and EIB incidence among healthy individuals. METHODS: Eighteen healthy, non-asthmatic, physically active volunteers (males/females: 14/4, age: 29.4 ± 5.9 years old, maximal oxygen consumption [V̇O2max]: 61.3 ± 8.7 ml/kg/min) who had never competed at the elite level, completed two moderate-intensity (60% V̇O2max) climate chamber running trials at -15 ºC lasting for 30 and 90 min in a randomized cross-over design. Impulse oscillometry (IOS) was conducted before, 12, and 50 min post-trials to assess resistance at 5 and 20 Hz as well as reactance at 5Hz. Forced expiratory volume in 1s (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio were measured via dynamic spirometry before, 15, and 55 min after the trials. Two-way repeated measures ANOVAs were performed to determine the impact of trial and time on the percentage change of IOS and spirometry variables. RESULTS: There were no significant effects of trial (30 min vs 90 min trial), time (pre-trial vs post-trial time points), or interaction effects for any spirometry or IOS variable. None of the participants exhibited EIB, defined as a ≥10% reduction in FEV1, at any time point (15 min after exercise: +0.37 ±1.95% for the 30 min trial and -0.25 ± 3.47% for the 90 min trial; 55 min after exercise: +0.85 ± 2.32% for the 30 min trial and +0.15 ± 3.97% for the 90 min trial). CONCLUSION: The acute lung function responses to exercise did not differ between the 30- and 90-min trials. Additionall