Controversies in the association of cardiorespiratory fitness and arterial stiffness in children and adolescents.

The relationship between cardiorespiratory fitness and arterial compliance in children and adolescents remains controversial. The aim of this study was to assess this association with a quantitative approach. A total of 646 healthy children and adolescents (316 females, age 13.9±2.1 years) were cross-sectionally investigated in seven school settings in and around Munich for their cardiorespiratory fitness and demographic, anthropometric and hemodynamic parameters. Surrogates of arterial stiffness, such as pulse wave velocity (PWV), Augmentation Index normalized to a heart rate of 75 (AI@75), and peripheral and central systolic blood pressures were measured in a supine position using the oscillometric Mobil-O-Graph. Cardiopulmonary fitness was measured by 6-min indoor run tests. After correction for age, sex, body weight, body height, heart rate and mean arterial pressure, controversial findings were produced. PWV increased with higher cardiorespiratory fitness (Beta=0.173; P<0.001), which represented an unfavorable relationship, whereas AI@75 declined with higher cardiorespiratory fitness (Beta=-0.106; P=0.025). Therefore, in contrast to PWV, higher cardiorespiratory fitness seems beneficial for AI@75. The third surrogate of arterial stiffness, central systolic blood pressure, showed no association with cardiorespiratory fitness (Beta=0.066; P=0.052). These controversial outcomes remain almost unchanged when the boys and girls were analyzed separately. Different surrogates of arterial stiffness have different relationships with cardiorespiratory fitness in children and adolescents after correcting for multiple confounders. More research is needed in this field to understand the functioning of the juvenile vessels, and measurements and methodological approaches should be reconsidered.