BackgroundChildhood asthma is a global problem affecting the respiratory health of children. Physical activity (PA) plays a role in the relationship between asthma and respiratory health. We hypothesized that a low level of PA would be associated with asthma in children and adolescents. The objectives of our study were to (1) summarize the evidence available on associations between PA and asthma prevalence in children and adolescents and (2) assess the role of PA in new-onset or incident asthma among children and adolescents.MethodsWe searched Medline, the Cochrane Library, and Embase and extracted data from original articles that met the inclusion criteria. Summary odds ratios (ORs) and confidence intervals (CIs) were used to express the results of the meta-analysis (forest plot). We explored heterogeneity using funnel plots and the Graphic Appraisal Tool for Epidemiology (GATE).ResultsWe retrieved 1,571 titles and selected 11 articles describing three cohort and eight cross-sectional studies for inclusion. A meta-analysis of the cohort studies revealed a risk of new-onset asthma in children with low PA (OR [95 % CI] 1.32 [0.95; 1.84] [random effects] and 1.35 [1.13; 1.62] [fixed effects]). Three cross-sectional studies identified significant positive associations between childhood asthma or asthma symptoms and low PA.ConclusionsChildren and adolescents with low PA levels had an increased risk of new-onset asthma, and some had a higher risk of current asthma/or wheezing; however, there was some heterogeneity among the studies. This review reveals a critical need for future longitudinal assessments of low PA, its mechanisms, and its implications for incident asthma in children. The systematic review was prospectively registered at PROSPERO (registration number: CRD42014013761; available at: http://www.crd.york.ac.uk/PROSPERO [accessed: 24 March 2016]).Electronic supplementary materialThe online version of this article (doi:10.1186/s12887-016-0571-4) contains supplementary material, which is available to authorized users.

The asthmatic participants presented with lower aerobic capacity than controls in both PAC and MAC; therefore, results confirmed the validity of the PAC method. Data warrant exploration by large-scale paediatric asthma epidemiology.

BackgroundAsthma in paediatric populations is one of the highest public health concerns. In this study of children and adolescents, we hypothesized that low levels of physical activity (PA) would show associations with asthma that vary by asthma outcome. The objective was to assess whether PA was associated with ever asthma and/or current asthma.MethodsAnalyses were based on 4824 Danish schoolchildren aged 11–15 years old (48.7% boys) participating in the HBSC survey. The study variables were (1) physician-diagnosed asthma (ever asthma) and (2) physician-diagnosed asthma plus wheezing and/or physician or hospital consultation for wheezing (current asthma). Associations with PA by gender were analysed with multivariate logistic regression using the “variance covariance (vce) cluster” method.ResultsThe prevalence of ever asthma was 14.3% (boys) and 12.8% (girls), and that of current asthma was 6.8% (boys) and 7.0% (girls). Boys with current asthma showed important differences in low and high PA. We found inverse associations between low PA and ever asthma, odds ratio [95% confidence interval] male: .55 [.30; .99] and female: .47 [.24; .93], and current asthma, male: .27 [.12; .60] (P linear trend = .007) and female: .32 [.11; .94].ConclusionsThe lowest activity levels showed significant inverse associations with asthma, regardless of the definition. For boys, the more stringent (current asthma) of the two paediatric asthma definitions revealed a significant trend with PA, and the direction of associations shifted to positive as weekly PA increased.Electronic supplementary materialThe online version of this article (10.1186/s40733-018-0042-9) contains supplementary material, which is available to authorized users.

Objective. To compare longitudinally PAC of asthmatic children against that of healthy controls during ten months. Methods. Twenty-eight asthmatic children aged 7–15 years and 27 matched controls each performed six submaximal exercise tests on treadmill, which included a test of EIA (exercise-induced asthma). Predicted aerobic capacity (mLO2/min/kg) was calculated. Spirometry and development were measured. Physical activity, medication, and “ever asthma/current asthma” were reported by questionnaire. Results. Predicted aerobic capacity of asthmatics was lower than that of controls (P = 0.0015) across observation times and for both groups an important increase in predicted aerobic capacity according to time was observed (P < 0.001). FEV1 of the asthmatic children was within normal range. The majority (86%) of the asthmatics reported pulmonary symptoms to accompany their physical activity. Physical activity (hours per week) showed important effects for the variation in predicted aerobic capacity at baseline (F = 2.28, P = 0.061) and at the T4 observation (F = 3.03, P = 0.027) and the analyses showed important asthma/control group effects at baseline, month four, and month ten. Physical activity of the asthmatics correlated positively with predicted aerobic capacity. Conclusion. The asthmatic children had consistently low PAC when observed across time. Physical activity was positively associated with PAC in the asthmatics.