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HEMODYNAMIC RESPONSE TO BLOOD FLOW RESTRICTION DURING EXERCISE USING THIGH BLOOD PRESSURE CUFFS

Abstract

Current theory regarding changes in mean arterial pressure (MAP) during exercise involve the regulation of MAP through the "resetting" of aortic and carotid baroreceptors to higher "set-points." However, the mechanisms for this are not completely understood. We proposed that MAP is controlled during exercise, and that the matching of blood flow (BF) demands and supplies is the regulated variable. PURPOSE: The purpose of this study was to examine BF rather than MAP as the primary regulated variable during exercise. METHODS: Fourteen (7 male and 7 female) physically active, college-aged subjects participated in this study with two factors of thigh compression: increased compression (IC) and no compression (NC), and two factors of BF demand: low demand (REST) and high demand (cycle ergometer exercise at 100 W (EX)). Each REST and EX trial lasted a total of 24 min, with 12 min of NC and 12 min of IC. Subjects' stroke volume (SV), cardiac output (CO) and heart rate (HR) were continuously monitored. MAP and oxygen saturation (O2 sSat) levels were measured during minutes 6, 8, and 10 of each resistance condition. RESULTS: Data was analyzed using a 2x2 repeated measures ANOVA (alpha = 0.05). There was a significant increase in MAP from the NC to IC condition during EX (p= 0.018), but not REST. There were no significant differences in CO, HR, SV, or O2 SAT between the NC and IC conditions in either REST or EX. CONCLUSION: Supply and demand of BF is regulated when there is high BF demand (exercise), but MAP is regulated during low aerobic conditions (rest) when there is less demand for BF.

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