Mediative role of body mass index in cardiorespiratory fitness-associated vascular remodeling in youth

BACKGROUND: Data on fitness-associated arterial remodeling in children is limited. We assessed the relation between cardiorespiratory fitness (CRF) and intima-media thickness (IMT), diameter, IMT:diameter-ratio (IDR), and tensile stress of the common carotid artery (CCA) in 697 healthy German schoolchildren. Further, we explored how body mass index (BMI) may influence these associations. METHODS: peak). RESULTS: peak, reflecting CRF, showed positive direct effects on IMT (girls: p < 0.001; boys: p = 0.02) and diameter in girls (p < 0.001). Considering BMI as a mediator, higher CRF was indirectly linked to decreases in IMT (girls: p = 0.04; boys: p = 0.02) and diameter (both p < 0.001), reflecting a competitive mediation. CRF indirectly mitigated the BMI-associated decrease in IDR (both p < 0.001) and increase in tensile stress (both p < 0.001) without affecting any of these parameters directly. CONCLUSION: CRF appears to be linked to uniform arterial remodeling with balanced hemodynamics and to further alleviate BMI-associated, potentially adverse vascular alterations, highlighting its significant role in cardiovascular health in youth. IMPACT: peak, reflecting higher CRF, was positively associated with IMT in girls and boys and diameter in girls. These direct effects were counteracted by the indirect BMI-mediated effect of CRF on IMT and diameter, reflecting a competitive mediation. A higher CRF indirectly mitigated the BMI-associated decrease in IDR and increase in tensile stress without directly affecting any of these parameters. Our findings indicate homogenous remodeling and balanced hemodynamics with increasing CRF-and opposite effects with increasing BMI.