Relationships of physical fitness and obesity with metabolic risk factors in children and adolescents: Chungju city cohort study.

Purpose: The purpose of this study was to investigate the relationships of physical fitness and obesity with metabolic risk factors in children and adolescents.

Methods: This cohort study was conducted in Chungju city, South Korea. Total 843 subjects were enrolled, including 193 elementary school 4th grade male (E4M), 189 elementary school 4th grade female (E4F) and 461 male-middle school students (M1M). The subjects were also classified into 2 groups by body mass index; normal weight (NW) group and overweight included obesity (OW/OB) group. Physical fitness was measured by shuttle run (cardiorespiratory fitness, CRF), sit and reach (flexibility), handgrip strength (muscular strength) and stand long jump (agility).

Results: The prevalence of OW/OB was respectively 33.7% (65 of 193) among E4M, 28.6% (54 of 189) among E4F, and 28.0% (129 of 461) among M1M. Hematocrit, white blood cell, triglyceride, low-density lipoprotein, insulin, homeostasis model assessment of insulin resistance, systolic and diastolic blood pressure were higher, while high-density lipoprotein were lower in the OW/OB group than in the NW group. The OW/OB group presented significantly lower CRF (P<0.01) and lower agility, but higher muscular strength compared with NW group. CRF was negatively correlated with obesity indices and metabolic risk factors. After adjustments for potential confounders, odds ratios for 4th-5th grade CRF of OW/OB compared NW in the E4M, E4F, M1M, were 7.38 (95 % CI, 3.24-16.83), 4.10 (95% CI, 1.83-9.18), 16.06 (95% CI, 8.23-31.00) (P<0.01).

Conclusion: Our study has shown that CRF has negative correlation with OW/OB in children and adolescents of Chungju city. We suggest that improvement of CRF through regular physical activity would be an important method for reducing the metabolic risks of childhood obesity.