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

Abstract

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. 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. 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 R(2) 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). 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): isrctn.org 15360785.