title: Physical activity in young children is reduced with increasing bronchial responsiveness.
abstract: BACKGROUND
  Physical activity is essential for young children to develop adequately and for quality of life. It can be lower in children with subclinical asthma, and therefore methods to reveal subclinical reduction in physical activity in young children are warranted.
  
  
  OBJECTIVE
  We sought to study an association between physical activity in preschool children and objectively assessed intermediary asthma phenotypes.
  
  
  METHODS
  We studied 253 five-year-old children (127 girls) participating in the Copenhagen Prospective Studies on Asthma in Childhood. The main outcome measure was level of physical activity assessed objectively with accelerometers worn on an ankle for 4 weeks. Objective assessment of asthma intermediary phenotypes included prebronchodilator and postbronchodilator specific airway resistance, bronchial responsiveness to cold dry-air hyperventilation, and exhaled nitric oxide levels. Analyses were performed with generalized linear model and principal component analysis.
  
  
  RESULTS
  Physical activity was inversely associated with bronchial responsiveness (relative rate, 0.89; 95% CI, 0.83-0.95; P = .007) and significantly increased in the months of spring and summer (P < .001) and in boys (relative rate, 1.16; 95% CI, 1.09-1.25; P < .001). Physical activity was independent of asthma diagnosis, age, body mass index, baseline specific airway resistance, reversibility to beta(2)-agonist, sensitization, and exhaled nitric oxide level.
  
  
  CONCLUSIONS
  Physical activity in preschool children was reduced with increasing bronchial responsiveness. The reduced physical activity was subclinical and not realized by parents or doctors despite daily diary cards and close clinical follow-up since birth. This observation warrants awareness of even very mild asthma symptoms in clinical practice.
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood; the Danish Pediatric Asthma Center, Health Sciences, University of Copenhagen; and Copenhagen University Hospital, Gentofte, Copenhagen, Denmark.
authors.forename: Martin
authors.initials: M
authors.lastname: Brasholt
authors.forename: Florent
authors.initials: F
authors.lastname: Baty
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D000403:Airway Resistance; D001249:Asthma / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D002675:Child, Preschool; D015331:Cohort Studies; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D009569:Nitric Oxide / Q000032:analysis; D025341:Principal Component Analysis; D012129:Respiratory Function Tests
chemical_list: D009569:Nitric Oxide