Body mass index and cardiorespiratory function among children and adolescents

Objective To describe the distribution of body mass index(BMI)by ages,genders and areas of children and adolescents in Anhui province,and to determinate the relationships between BMI and vital capacity,diastolic blood pressure,systolic blood pressure and pulse.Methods A total of 9 000 participants were recruited in Anhui province in the National Survey on Student Constitution and Health in 2005.To describe the distribution of BMI by age,gender and areas of children and adolescents.The distribution of Z scores of vital capacity,vital capacity index,diastolic blood pressure,systolic blood pressure and pulse by Z score of BMI were described.The correlations of Z scores of BMI,vital capacity,vital capacity index,diastolic blood pressure,systolic blood pressure and pulse were analysed.Results BMI was rising with the age by genders and areas at a consistent tendency among children and adolescent aged 6 to 22,and the genders' variance of BMI was significant compared with the variance between urban and rural students.Positive correlations were found between Z score of vital capacity,diastolic blood pressure,systolic blood pressure and Z score of BMI(P=0.000).It appeared a negative correlation between Z score of vital capacity index and X score of BMI(P=0.000).There was no linear association between pulse Z score and BMI Z score(r=0.006,P=0.552).Conclusion BMI curves of boy's and girl's present a cross feature at puberty.There is a little urban-rural variance of BMI among elder adolescent.With the BMI increase,vital capacity index descends and blood pressure increases in children and adolescents.It is necessary to supervise early cardiorespiratory function of children and adolescents with higher BMI.