Bibliografisk note

Funding Information:
The Center for Physical Activity Research (CFAS) is supported by TrygFonden (grants ID 101390 and ID 20045 ).

Funding Information:
Dr ESH Hansen has no relevant conflicts of interest to declare. Dr C. Tidemandsen has no relevant conflicts of interest to declare. Dr SM Rasmussen has no relevant conflicts of interest to declare. Professor V. Backer has received an unrestricted grant for an asthma and fertility study by Novartis, has been part of advisory boards concerning asthma therapy by GSK, Teva, Chiesi, MSD, Novartis, AZ. Professor CS Ulrik has received personal fees for lectures, advisory board meetings, and so one, from AstraZeneca, Novartis, Chiesi, TEVA, GSK, ALK-Abello, Boehringer-Ingelheim, Mundipharma, Actelion, Orion Pharma, Sanofi and Mylan.The Center for Physical Activity Research (CFAS) is supported by TrygFonden (grants ID 101390 and ID 20045).