Physical Fitness Is A Stronger Predictor Of Cardiac Morphology Than Body Composition In Children

Obesity in childhood is associated with several negative health outcomes, especially in cardiac morphology, and physical fitness has been shown to positively affect cardiac measures. PURPOSE: To determine whether body composition or fitness is a better indicator of cardiac morphology in otherwise healthy adolescents. METHODS: Non-obese (NB, n = 20) and obese (OB, n = 7) children ages 12-14 underwent maximal exercise testing on a cycle ergometer to determine VO2max. Resting cardiac measurements, including left and right ventricular mass (LVM, RVM), LV and RV end diastolic volume (LVEDV, RVEDV), LV and RV end systolic volume (LVESV, RVESV), LV and RV stroke volume (LVSV, RVSV), and LV and RV ejection fraction (LVEF, RVEF), and percent body fat determinations were acquired by magnetic resonance by a 3-T CMR scanner (Discovery 750). Groups were compared across body composition (NB, OB) and fitness levels (high, low) using least squares means from age and sex adjusted linear models. The independent influences of fitness and body composition on cardiac variables were evaluated with age and sex-adjusted linear models. RESULTS: OB children had significantly higher LVM and RVM than NB children (79.9 [70-90] v 66.1 [60-72]g, p = 0.02). High fitness children had significantly higher LVM and RVM (78.3 [72-84]v 60.5 [54-67]g, 14.9 [14-16]v 10.5 [9.1-12]g, respectively), higher LV and RVEDV (154 [140-170]v 130 [120-140]ml, 156 [140-170]v 132 [120-140]ml, respectively), and higher LV and RVESV (64.7 [60-69]v 54 [49-59], 72.2 [67-78]v 59.7 [54-66]ml) than the low fitness group. Obesity was an independent predictor of LVM and RVM, whereas fitness was an independent predictor of several cardiac morphology variables (see table). CONCLUSIONS: Our study found that while both obesity and fitness are predictors of cardiac mass in otherwise healthy adolescents, greater fitness is a stronger predictor of LVM and RVM and chamber size in this population, regardless of body composition.Supported by: NIH