Relationship between aortic augmentation index and blood pressure during metaboreflex activation in healthy young men

BACKGROUND: Heightened aortic augmentation index (AIx; surrogate of arterial stiffness) is associated with an elevated risk of cardiovascular events; however, it is currently unclear whether peripheral blood pressure (BP) modulates AIx. AIM: Given this, we studied the relationship between AIx and BP under resting conditions as well as during skeletal muscle metaboreflex activation, which is a maneuver that generates steady elevations in BP. METHODS: In nine healthy male participants (23±2 years), the graded activation of the muscle metaboreflex was achieved by postexercise ischemia (PEI) following moderate and high-intensity static handgrip performed at 30 and 40% maximum voluntary contraction. Heart rate (ECG), arterial BP, and AIx (SphygmoCor) were measured. RESULTS: Compared with rest, mean arterial pressure was significantly increased during PEI30% (+24±4 mmHg, P<0.05 vs. rest) and was further augmented during PEI40% (+34±4 mmHg, P<0.05 vs. PEI30%). Similarly, AIx@HR75 increased significantly from rest during PEI30% (rest -9±3% vs. PEI30% +9±5%, P<0.05) and was further augmented during PEI40% (17±4%, P<0.05 vs. PEI30%). At rest, there was no relationship between AIx and BP. However, at PEI30%, there was a significant association between AIx and diastolic BP and mean arterial pressure (r=0.92, 0.87, respectively; P<0.05) and this association was maintained at PEI40% (r=0.94, 0.91, respectively; P<0.05). CONCLUSIONS: Our results indicate that acute elevations in peripheral BP are an important determinant of AIx during muscle metaboreflex activation in healthy men.