Background: The prevalence of obesity in children has increased substantially in recent years and, paediatric obesity and poor fitness are risk factors for disease. The present study aimed to assess changes in body mass index (BMI), the prevalence of obesity and changes in aerobic endurance over time in 9-10-year-old schoolchildren.
Methods: Participants were recruited by the SportsLinx project from primary schools across Liverpool. Height and weight data were used to calculate BMI. The prevalence of obesity and overweight were estimated using age- and sex-specific cut-off points. Performance on the 20-m multi-stage shuttle runs test (20 mMST) was used as a marker of aerobic endurance. Data were available for 13,418 (6572 boys, 6846 girls) 9-10-year-old children. Analysis of covariance was completed to assess year-on-year changes in BMI controlling for deprivation (IMD) and 20 mMST performance, and 20 mMST performance controlling for IMD and BMI.
Results: No significant changes in BMI from baseline were observed (P > 0.05). Obesity prevalence reduced in girls (2005 = 10.3%, 2008 = 8.52% in 2008). The data for boys showed no reductions in prevalence (2005 = 6.77%, 2008 = 7.87%). The most recent cohort for boys and two most recent cohorts for girls had lower levels of aerobic endurance than baseline (2004-2005) (P <or= 0.01).
Conclusions: The data suggest a plateau in the yearly increases in BMI in 9-10 year olds independent of deprivation and fitness and a declining prevalence of obesity in girls. Levels of aerobic endurance have declined independent of BMI and deprivation. The current obesity interventions in place appear to be having some impact on BMI, but further investment is urged to promote fitness in children.