Race Affects Elastance Responses Following Endurance Exercise Training

The ventricular-vascular coupling ratio is comprised of the ratio of arterial elastance to ventricular elastance. Briefly, arterial elastance (Ea) may be described as total arterial load, and ventricular elastance (Elv) also considers both geometric and physiological variables to quantify left ventricular stiffness. Together, these measures may be indexed to body size (EaI and ElvI) to compile a load-independent portrayal of net cardiac and vascular interaction. Optimal EaI/ElvI results in ideal coronary perfusion and blood distribution to the periphery. Blood pressure (BP) and arterial stiffness are important determinants of EaI/ElvI. African Americans (AA) have consistently been reported to have higher large artery stiffness and BP compared to Caucasian Americans (CA). However, exercise training reduces both BP and large artery stiffness. Our purpose was to determine the effects of race on coupling after an 8 week exercise training intervention. We hypothesized a reduction in the ratio due to a reduction in EaI that would be more pronounced in CA compared to AA adults. We used applanation tonometry to measure central blood pressures and carotid-femoral pulse wave velocity to quantify central arterial stiffness and cardiac ultrasonography to quantify LV volumes before and after our training intervention. We used the formulas: Ea=ESP/SV and Elv=ESP/ESV and divided these numbers by BSA as calculated using Mostellar’s formula. Both AA and CA maintained their pre-training coupling ratios (p>0.05 for time effect and race*time interaction), however, CA did so by uniformly augmenting both EaI and ElvI (Ea was 0.76±0.1 to 0.77±0.09 mmHg/ml/m2 in AA and 0.68±0.09 to 0.75±0.1 mmHg/ml/m2, p=0.02 for CA; ElvI was 1.20±0.11 to 1.22±0.1 mmHg/ml/m2 in AA and 0.99±0.1 to 1.16±0.1 mmHg/ml/m2 in CA p0.05). This occurred despite similar reductions in central arterial stiffness, BP, and ESP in both races. We conclude that, although the coupling ratio was similarly maintained in CA and AA, the responses to training were quite different.published or submitted for publicationis peer reviewe