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OBJECTIVE: Asthma is common among elite endurance athletes. Since the first published Swedish studies in 1993, awareness of "skiers' asthma" has increased. The current prevalence of asthma among Swedish skiers is unknown. This paper aims to present the design of a 5-year prospective annual questionnaire study on asthma among Swedish current and former elite endurance athletes, the first cross-sectional results on prevalence, age of onset, and predictors of self-reported physician-diagnosed asthma in the study population.

METHODS: An annual postal questionnaire is sent to Swedish elite skiers and orienteers during 2011-2015. In 2013, former Swedish Olympic skiers were similarly invited. We present cross-sectional data obtained in 2011 from the adolescents and adults and in 2013 from former skiers. A total of 491 athletes were invited. The results are presented by age, sex and sport. Chi-square test was used for group comparisons. Predictors of asthma were identified using logistic regression.

RESULTS: Response rate was 82%. Among athletes aged 15-19, 29% of the skiers (38% of the female skiers), and 17% of the orienteers reported asthma (p = 0.071). Among the athletes aged 20-34, 35% of the skiers and 16% of the orienteers reported asthma (p = 0.029). Among the former skiers aged 40-94, 22% reported asthma. Among the active athletes, the onset of asthma was in early adolescence. Logistic regression found increasing age, female sex, allergy, family history of allergy/asthma and being skier predictors of self-reported physician-diagnosed asthma.

CONCLUSIONS: The prevalence of physician-diagnosed asthma is high among Swedish endurance athletes, especially female adolescent skiers.

The objective of the study was to compare the prevalence of self-reported physician-diagnosed asthma and age at asthma onset between Swedish adolescent elite skiers and a reference group and to assess risk factors associated with asthma. Postal questionnaires were sent to 253 pupils at the Swedish National Elite Sport Schools for cross-country skiing, biathlon, and ski-orienteering (skiers) and a random sample of 500 adolescents aged 16-20, matched for sport school municipalities (reference). The response rate was 96% among the skiers and 48% in the reference group. The proportion of participants with self-reported physician-diagnosed asthma was higher among skiers than in the reference group (27 vs 19%, P=.046). Female skiers reported a higher prevalence of physician-diagnosed asthma compared to male skiers (34 vs 20%, P=.021). The median age at asthma onset was higher among skiers (12.0 vs 8.0years; P<.001). Female sex, family history of asthma, nasal allergy, and being a skier were risk factors associated with self-reported physician-diagnosed asthma. Swedish adolescent elite cross-country skiers have a higher asthma prevalence and later age at asthma onset compared to a reference population. Being an adolescent, elite skier is an independent risk factor associated with asthma.

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: 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.