Independent associations between cardiorespiratory fitness, waist circumference, BMI and clustered cardiovascular disease risk in adolescents

BACKGROUNDThe literature is scarce regarding the potential independent roles of both adiposity and cardiorespiratory fitness upon clustered metabolic risk and markers of inflammation in youth. Thus, the purpose of this study was to examine the independent associations between measures of adiposity and cardiorespiratory fitness with clustered metabolic risk in adolescents.
METHODSubjects for this cross-sectional study were 209 adolescents (139 boys), aged 15 – 17.5 years from the West of Scotland, and recruited from a South Lanarkshire school. Participants completed a number of anthropometric measurements (height, weight, and waist circumference (WC)). The 20 m multi-stage fitness test was used to assess cardiorespiratory fitness (CRF). Age- and gender-specific z-scores of systolic blood pressure, triglycerides, ratio total cholesterol/high-density lipoprotein cholesterol, insulin resistance (homeostasis model assessment), interleukin-6, C-reactive protein (CRP) and adiponectin (inverted) were summed to create a clustered metabolic risk score.
RESULTSPartial correlations revealed weak to moderate negative associations for BMI and WC with CRF (r = -0.279 and – 0.274, P < 0.001) and adiponectin (r = -0.225 and -0.263, P < 0.05) whereas weak to moderate positive associations were evident for BMI with CRP, and clustered metabolic risk (r = 0.220, and 0.277, P < 0.05, respectively). Weak to moderate positive associations were apparent for WC with CRP and triglycerides (r = 0.222 and 0.253, P < 0.05), whilst a moderate to large association was evident for WC with clustered metabolic risk (r = 0.305, P < 0.05). Regression analyses controlling for age, sex and maturation revealed that BMI was positively associated with clustered metabolic risk (β = 0.240, P = 0.002). Further analysis whilst additionally controlling for WC and CRF strengthened the association between BMI and clustered metabolic risk (β = 0.341, P = 0.002). Finally, participants in the least-fit quartile for CRF had significantly poorer clustered metabolic risk scores than all of those in the other quartiles.
DISCUSSIONWhilst the observations of this study are limited due to its cross-sectional nature, small sample size and indirect assessment of CRF, our findings do provide evidence of the importance of adiposity and CRF measures upon CVD risk factors and clustered metabolic risk.