Fatness and fitness with cardio-metabolic risk factors in adolescents

Context: The relative importance of fitness and fatness with cardio-metabolic risk factors are uncertain during the crucial developmental stage of late adolescence.

Objective: We aimed to compare the concurrent influences of cardiorespiratory fitness and fatness in relation to cardio-metabolic risk factors in adolescents from the Western Australian Pregnancy Cohort Study.

Design, Setting and Participants: Cross-sectional analysis was performed on 1128 participants with complete blood pressure data and 963 participants with complete blood biochemistry at 17 years of age. Fatness (waist circumference) and cardiorespiratory fitness (PWC170) were assessed as continuous measures to avoid the use of arbitrary cut points. Analyses used linear regression models adjusted for sex and potential lifestyle confounders.

Main Outcome Measure: Cardio-metabolic risk factors.

Results: Fatness was positively associated with systolic BP (coefficient, 0.19; P < 0.001; β coefficient, 0.20), triglycerides (log coefficient, 0.009; P < 0.001; β coefficient, 0.24), low-density lipoprotein cholesterol (coefficient, 0.005; P = 0.007; β coefficient, 0.10), and high-sensitivity C-reactive protein (log coefficient, 0.05; P < 0.001; β coefficient, 0.35). There were no significant effects of fitness on any of these measures. A positive association between homeostasis model of assessment for insulin resistance and fatness (log coefficient, 0.02; P < 0.001; β coefficient, 0.33) was attenuated by fitness (log coefficient, -0.0.18; P < 0.001; β coefficient, -0.18). Fatness was inversely associated with high-density lipoprotein cholesterol (HDL-C) in both sexes (coefficient, -0.006; P < 0.001; β coefficient, -0.23), whereas fitness was positively associated with HDL-C only in females (coefficient, 0.08; P = 0.03; β coefficient, 0.15).

Conclusions: The adverse effects of central adiposity seen across a broad range of cardio-metabolic risk factors were only partially ameliorated by fitness in this adolescent population.