Importance of individual hemodynamic thresholds during exercise (Hem-TRex): relationship with blood pressure

Abnormal blood pressure (BP) responses to exercise are independently associated with cardiovascular disease. However, the physiological mechanisms underlying exercise BP are unclear, with traditional focus on examining differences in the slope (increase) of BP, or on the absolute maximal BP achieved during incremental exercise. Considering that cardiac function (stroke volume and myocardial deformation) and systemic hemodynamics (e.g, systemic vascular resistance, SVR) are known to reach their peak (i.e. plateau) at submaximal exercise [1, 2], different exercise BP progressions could be related to the individually varied attainment of peak hemodynamics. Indeed, young individuals with high BP (at rest) may be categorized into those that have a disproportionately high cardiac output (Q) and those who have a high systemic vascular resistance (SVR) [3]. Identifying the temporal attainment of peak Q and lowest SVR (i.e., their hemodynamic threshold during exercise, “ Hem-TRex ” ) could, therefore, offer new insight to the physiology of exercise BP. Thus, the aim of this exploratory study was to determine individual Hem-TRex of Q and SVR, and their relationship with the Hem-TRex of BP. Based upon the previously suggested phenotypes, it was hypothesized that individuals who reach their peak Q early during incremental exercise would attain their lowest SVR later during incremental exercise, re fl ecting an inverse association, and that this may relate to exercise BP. Participants (12 healthy young individuals;7 M, 5 F) completed two visits. Visit 1 determined W peak during a maximal incremental test on a supine, tilted ergometer; Visit 2 consisted of 3-min stages starting at 40% of Visit-1 W peak and increasing by 10% W peak per stage until volitional exhaustion. Baseline brachial BP was assessed using an oscillometric