Aerobic capacity related to cardiac size in young children

Aim. Aerobic capacity, defined as peak oxygen uptake (VO _2PEAK), is generally considered to be the best single marker for aerobic fitness. We assessed if V0 _2PEAK is related to different cardiac dimensions in healthy young children on a population base. Methods. In a cross-sectional study, 245 children (137 boys and 108 girls) aged 8-11 years, were recruited from a population based cohort V0 _2PEAK (ml/min ^-1/kg ^-1) was assessed by indirect calorimetry during a maximal exercise test DXA-scan was used to measure lean body mass (LBM) and total fat mass (TBF). Echocardiography, with 2-dimensional guided M-mode, was performed in accordance with current guidelines. Left ventricular end-diastolic diameter (LVDD) and left atrial end-systolic diameter (LA) were measured, and left ventricular mass (LVM) was calculated. Results. Univariate correlations were found between VO _2PEAKversus LVDD r=0.44 and LA r=0.27 (both P≤0.05) and LVM r=-0.06 (NS) in boys. Corresponding values for girls were; 0.55, 034 (both P≤0.05) and 0.11 (NS). Multiple regression analysis with VO _2PEAK as dependent variable and inclusion of LBM, TBF, sex, age, Tanner stage, and maximal heart rate as independent variables showed that 67% of the total variance of VO _2PEAK could be explained by these variables. Including LVDD or LA in the model, added 1% additional explained variance. Conclusion. Findings from this population based cohort of young healthy children show that multiple cardiac dimensions at rest are related to VO _2PEAK. However, the different cardiac dimensions contributed very little to the added explained variance of VO _2PEAK.