title: Sex differences in habitual physical activity and lung function decline in children with cystic fibrosis.
abstract: OBJECTIVE
  To evaluate the feasibility of measuring habitual physical activity (HPA) in children with cystic fibrosis (CF) and to assess the relation between HPA and the rate of decline in FEV1 over a period of 2 years.
  
  
  METHODS
  At regular clinic visits, 109 patients (7 to 17 years; 56 girls) performed pulmonary function testing and completed the Habitual Activity Estimation Scale (HAES). Patients were divided into quartiles, based on activity levels derived from the HAES.
  
  
  RESULTS
  Girls in the two lowest activity quartiles had a more rapid rate of decline FEV1 (-3.40% and -3.05% predicted, respectively) than girls in the two highest activity quartiles (-0.93% and +1.17% predicted, respectively) (P = .02). In boys, the rate of decline of FEV1 was similar in all activity quartiles (-1.95% predicted). Patients reported significantly more activity in summer compared with spring, winter, and fall (P < .0001), and boys reported greater activity than girls (6.5 +/- 2.9 vs 5.4 +/- 2.5 h/d, P < .05).
  
  
  CONCLUSIONS
  The annual rate of change of FEV1 was related to activity quartile in girls but not in boys. This research suggests that an inactive lifestyle may partially explain the poorer survival of female patients with CF. The HAES is a feasible tool for routine follow-up of HPA in our CF clinic.
authors.affiliation: Division of Respiratory Medicine, Hospital for Sick Children, Research Institute, Toronto, Ontario, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Schneiderman-Walker
authors.forename: D L
authors.initials: DL
authors.lastname: Wilkes
authors.forename: L
authors.initials: L
authors.lastname: Strug
authors.forename: L C
authors.initials: LC
authors.lastname: Lands
authors.forename: S L
authors.initials: SL
authors.lastname: Pollock
authors.forename: H C
authors.initials: HC
authors.lastname: Selvadurai
authors.forename: J
authors.initials: J
authors.lastname: Hay
authors.forename: A L
authors.initials: AL
authors.lastname: Coates
authors.forename: M
authors.initials: M
authors.lastname: Corey
mesh_terms: D000293:Adolescent; D002648:Child; D003550:Cystic Fibrosis / Q000401:mortality / Q000503:physiopathology* / Q000523:psychology; D015444:Exercise / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D005541:Forced Expiratory Volume; D006184:Habits; D015438:Health Behavior; D006801:Humans; D008019:Life Style; D008137:Longitudinal Studies; D008168:Lung / Q000503:physiopathology*; D008297:Male; D012737:Sex Factors; D015996:Survival Rate