Adiposity, fitness and metabolic risk in children: A cross-sectional and longitudinal study

Abstract

Objective. To better understand the early development of cardiovascular disease, we examined the association of adiposity measures and cardiorespiratory fitness (CRF) with baseline values and changes in low-grade chronic inflammation and insulin resistance (IR) in school children. Methods. Eighty-three 1^st and 5^th grade children from a randomly selected control group of a physical activity intervention study (KISS) were prospectively studied during one academic year. Outcome variables included highly sensitive C-reactive protein (hs-CRP) and homeostasis assessment of IR (HOMA-IR). Adiposity measures included body mass index (BMI), waist circumference and the sum of skinfold thickness at four sites. CRF was assessed by the 20 m shuttle run test. All models were adjusted for age group, sex and pubertal group and included children who had a complete valid dataset for all variables. Results. Baseline metabolic markers correlated positively with measures of adiposity and inversely with CRF (all p ≤ 0.02). On average, longitudinal changes in hs-CRP concentration increased with high baseline BMI in boys and skinfold thickness in both genders (both p < 0.01). Increases in adiposity had an additional effect on these changes (adjusted R² of the models including baseline and change in adiposity 0.49–0.53, p < 0.001). On the other hand, longitudinal changes in HOMA-IR were positively related to changes in BMI and waist circumference (p ≤ 0.03). Increases in HOMA-IR, but not in hs-CRP concentrations, were associated with low baseline CRF (p = 0.01). Conclusion. The relationship of baseline adiposity and CRF with increases in metabolic risk markers may have relevant implications for long-term cardiovascular risk.

International Standard Randomised Controlled Trial Number (ISRCTN): Trial registration: isrctn.org 15360785

Key words::

• Physical fitness
• aerobic fitness
• obesity
• cardiovascular disease
• metabolic syndrome
• inflammation
• insulin resistance
• child

Acknowledgements

We thank all the children, parents and teachers who volunteered to participate in this study. We thank Prof U. Keller for the helpful discussions, and U. Dürring, U. Schild and V. Wyss, Division of Endocrinology, Diabetes and Clinical Nutrition, University of Basel, for their competent assistance in collecting, transporting and centrifuging the blood samples, respectively. We appreciate the donation of the anesthetic patches by Astra Zeneca, Zug, Switzerland. We also appreciate the help of the assistants of the Institute of Exercise and Health Sciences, Basel. This study was supported by the Federal office of Sports, Magglingen, Switzerland, the Swiss National Science Foundation (Grants No 3234-069271 and PMPDB-114401), as well as the Diabetes Foundation of the Region of Basel.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.