title: Cardiorespiratory fitness and body mass index of 9-11-year-old English children: a serial cross-sectional study from 1998 to 2004.
abstract: OBJECTIVE
  To examine the changes over time in cardiorespiratory fitness and body mass index (BMI) of children.
  
  
  METHODS
  Serial cross-sectional, population-based study.
  
  
  METHODS
  Primary schools in Liverpool, UK.
  
  
  METHODS
  A total of 15,621 children (50% boys), representing 74% of eligible 9-11-year olds in the annual school cohorts between 1998/9 and 2003/4, who took part in a 20m multi-stage shuttle run test (20mMST).
  
  
  METHODS
  Weight, height, BMI (kg/m(2)) and obesity using the International Obesity Taskforce definition.
  
  
  RESULTS
  Median (95% confidence interval) 20mMST score (number of runs) fell in boys from 48.9 (47.9-49.9) in 1998/9 to 38.1 (36.8-39.4) in 2003/4, and in girls from 35.8 (35.0-36.6) to 28.1 (27.2-29.1) over the same period. Fitness scores fell across all strata of BMI (P<0.001). Moreover, BMI increased over the same 6-year period even among children in fittest third of 20mMST.
  
  
  CONCLUSIONS
  In a series of uniform cross-sectional assessments of school-aged children, BMI increased whereas cardiorespiratory fitness levels decreased within a 6-year period. Even among lean children, fitness scores decreased. Public health measures to reduce obesity, such as increasing physical activity, may help raise fitness levels among all children - not just the overweight or obese.
authors.affiliation: Research into Activity and Children's Health Group, Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, UK. g.stratton@ljmu.ac.uk
authors.forename: G
authors.initials: G
authors.lastname: Stratton
authors.forename: D
authors.initials: D
authors.lastname: Canoy
authors.forename: L M
authors.initials: LM
authors.lastname: Boddy
authors.forename: S R
authors.initials: SR
authors.lastname: Taylor
authors.forename: A F
authors.initials: AF
authors.lastname: Hackett
authors.forename: I E
authors.initials: IE
authors.lastname: Buchan
mesh_terms: D015992:Body Mass Index; D002320:Cardiovascular Physiological Phenomena; D002648:Child; D003430:Cross-Sectional Studies; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000503:physiopathology*; D050177:Overweight / Q000453:epidemiology* / Q000503:physiopathology*; D010809:Physical Fitness; D015995:Prevalence; D012143:Respiratory Physiological Phenomena; D012307:Risk Factors