Time spent in vigorous physical activity is associated with increased exhaled nitric oxide in non-asthmatic adolescents Christine Sachs-Olsen 1 , Sveinung Berntsen 1,2 *, Karin Cecilie Lødrup Carlsen 1,3 , Sigmund Alfred Anderssen 2 , Petter Mowinckel 1 and Kai-Håkon Carlsen 1,2,3 1 Department of Paediatrics, Oslo University Hospital, Oslo, Norway 2 Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway 3 Faculty of Medicine, University of Oslo, Oslo, Norway Abstract Introduction: Physical activity (PA) is important in preventing disease, but endur- ance elite athletes have increased prevalence of asthma and airway inflammation. Objectives: We aimed to determine if PA was associated with increased fractional exhaled nitric oxide (FENO) in asthmatic and non-asthmatic adolescents. Methods: FENO was recorded (Niox Mino®, Aerocrine AB, Stockholm, Sweden) in 169 adolescents (13–14 years) in a nested case–control analysis from the Environ- ment and Childhood Asthma study, Oslo, 92 adolescents with and 77 without asthma. They underwent clinical examination, lung function measurements and treadmill run measuring peak oxygen uptake, and objectively recorded PA for four consecutive days. PA was classified as moderate, vigorous and very vigorous, and total number of hours of each category was recorded for each subject. Associations between FENO and PA were tested using linear robust multiple regression analyses. Results: In non-asthmatic adolescents, FENO was associated with daily hours of vigorous to very vigorous (r = 0.27, P = 0.02) and very vigorous PAs (r = 0.25, P = 0.036) in bivariate analyses. In multivariate analyses, FENO was associated with vigorous to very vigorous PA [regression coefficients (95% confidence interval) 1.9 (0.6, 3.1); P = 0.004] and more strongly with very vigorous PA [3.9 (1.5, 6.4); P = 0.002] in non-asthmatic but not in asthmatic adolescents. Total daily PA was not associated with FENO in either group. Thus, 1 h of very vigorous PA per day increased FENO by 3.9 ppb. Conclusion: Vigorous to very vigorous PA, contrasting total daily PA, was signifi- cantly associated with increased FENO in non-asthmatic adolescents, suggesting that intensive PA may induce airway inflammation independent of asthma. Please cite this paper as: Sachs-Olsen C, Berntsen S, Lødrup Carlsen K, Anderssen SA, Mowinckel P and Carlsen K-H. Time spent in vigorous physical activity is associated with increased exhaled nitric oxide in non-asthmatic adolescents. Clin Respir J 2012; DOI:10.1111/j.1752-699X.2012.00283.x. Introduction Development of childhood asthma is influenced by multiple factors including hereditary disposition, aller- gic sensitisation and environmental factors. Increasing attention is also paid to the association between lif- estyle, physical activity (PA) and asthma (1). Aerobic fitness has been shown to be inversely related to the development of physician-diagnosed asthma in Danish children (2), and asthma management includes encouragement of participation in regular PA (1). Conversely, elite endurance athletes are at risk of Key words adolescent – asthma – child – exhaled nitric oxide – inflammation – physical activity Correspondence Christine Sachs-Olsen, MD, Department of Paediatrics, Oslo University Hospital, Rikshospitalet, Pb. 4950 Nydalen, NO-0424, Oslo, Norway. Tel: +47 23070000/+47 99241675 Fax: +47 23072290 email: c.sachs@online.no Received: 28 June 2011 Revision requested: 16 December 2011 Accepted: 17 January 2012 DOI:10.1111/j.1752-699X.2012.00283.x Authorship and contributorship All authors have contributed substantially to the planning and design of the study, data interpretation, writing and critical appraisal of the report and in the decision to submit the manuscript for publication. Christine Sachs-Olsen and Sveinung Berntsen have also been involved in data collection. Ethics The study was approved by the Medical Research Ethics Committee and was performed in accordance with the ethical standards of the 2000 Declaration of Helsinki. Written informed consent was obtained from all participating children and their parents. Conflicts of interest The authors have stated explicitly that there are no conflicts of interest in connection with this article. *Present address for Sveinung Berntsen: Department of Public Health, Sport and Nutrition, Faculty of Health and Sport Sciences, University of Agder, Norway The study is performed within the ORAACLE (the Oslo Research group for Asthma and Allergy in Childhood; the Lung and Environment), which is part of the GA 2 LEN network. GA 2 LEN is a project of the EU 6 th framework programme for research contract no. FOOD-CT-2004–506378. The Clinical Respiratory Journal ORIGINAL ARTICLE 1 The Clinical Respiratory Journal (2012) • ISSN 1752-6981 © 2012 Blackwell Publishing Ltd