Influence of physical inactivity on the prevalence of hay fever

Background: Atopic diseases constitute a major public health problem, increasing constantly in frequency and severity. While treatments are improving, the main cause for an increasing trend of hay fever and its definite triggers remain unclear. The aim of our study was to assess whether physical inactivity could be a risk factor for hay fever. Methods: We analysed data of a cohort of children aged 5-14 years at baseline (1992-1993) who were followed up until 2003-2005. Parental-reported information on physical activity (being active, doing sports) was obtained for 2429 children participating at the baseline survey (active: n = 1923; semi-active: n = 364; inactive: n = 142). A total of 1703 children (70.1%) were reapproached at least once during follow-up. Logistic regression models were applied to study associations between hay fever, allergic sensitization and physical activity, adjusted for potentially relevant confounders such as age, gender, study site, parental education, breastfeeding, crowding, daycare, dampness or visible moulds, contact to cats, current or prior environmental tobacco smoke exposure and parental atopy. Results: Significantly higher rates of hay fever were seen for inactive children [aOR 2.39 (95% CI 1.31-4.36) for baseline survey 1992-1993 and aOR 1.76 (95% CI 1.14-2.71) for the follow-up-period until 2005]. In addition, the relative risk of incident cases of hay fever increased depending on inactivity [aRR 1.50 (95% CI 1.05-2.13)]. No association was found between physical inactivity and allergic sensitization assessed by radioallergosorbent test determinations. Conclusions: Although the underlying biological mechanisms could not be clarified, increasing physical activity in childhood is suggested to prevent hay fever.