Cardiorespiratory fitness and body mass index of 9-11-year-old English children: a serial cross-sectional study from 1998 to 2004

Int J Obes (Lond). 2007 Jul;31(7):1172-8. doi: 10.1038/sj.ijo.0803562. Epub 2007 Feb 20.


Objective: To examine the changes over time in cardiorespiratory fitness and body mass index (BMI) of children.

Design: Serial cross-sectional, population-based study.

Setting: Primary schools in Liverpool, UK.

Participants: 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).

Main outcome measures: 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.

Conclusion: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Body Mass Index*
  • Cardiovascular Physiological Phenomena
  • Child
  • Cross-Sectional Studies
  • England / epidemiology
  • Female
  • Humans
  • Male
  • Obesity / epidemiology*
  • Obesity / physiopathology*
  • Overweight / epidemiology*
  • Overweight / physiopathology*
  • Physical Fitness*
  • Prevalence
  • Respiratory Physiological Phenomena
  • Risk Factors