PHYSICAL-FITNESS OF 9-YEAR-OLDS IN ENGLAND - RELATED FACTORS

Study objective - To examine the influence of social factors, passive smoking, and other parental health related factors, as well as anthrop ometric and other measurements on children's cardiorespiratory fitness . Design - This was a cross sectional study. Setting-The analysis was based on 22 health areas in England. Participants - The subjects were 299 boys and 282 girls aged 8 to 9 years. Parents did not give positiv e consent for 15% of the eligible sample. A further 25% of the eligibl e sample did not participate because the cycle-ergometer broke down, s tudy time was insufficient, or they were excluded from the analysis be cause they were from ethnic minority groups or had missing data on one continuous variable. Measurements and main results - Cardiorespirator y fitness was determined using the cycle-ergometer test. It was measur ed in terms of PWC85% - that is, power output per body weight (watt/kg ) assessed at 85% of maximum heart rate. The association between child ren's fitness and biological and social factors was analysed in two st ages. Firstly, multiple logistic analysis was used to examine the fact ors associated with the children's ability to complete the test for at least four minutes. Secondly, multiple linear regression analysis was used to examine the independent association of the factors with PWC85 %. In the logistic analysis, shorter children, children with higher bl ood pressure, and boys with a larger sibship size had poorer fitness. In the multiple regression analysis, only height (p < 0.001) was posit ively associated, and the sum of skinfold thicknesses at four sites (p = 0.001) was negatively associated with fitness in both sexes. In gir ls, a positive association was found with pre-exercise peak expiratory flow rate (p < 0.05), and there were negative associations with systo lic blood pressure (p < 0.05) and family history of heart attack (p < 0.05). In boys an association was found with skinfold distribution and fitness (p < 0.05), so that children with relatively less body fat we re fitter. Social and health behaviour factors such as father's social class, father's employment status, or parents' smoking habits were un related to child's fitness. Conclusion - Height and obesity are strong ly associated, and systolic blood pressure to a small extent, with chi ldren's fitness, but social factors are unrelated.