Our purpose was to compare common modes of rehydration (REHY) on cardiovascular and fluid regulation recovery following exercise dehydration (EXDE). Twelve non-heat-acclimatized trained subjects (23±4y, 81.3±3.7kg, 180±6cm, 56.9±4.4mLminkg VO2max, 7.8±3.0 % body fat) completed 20-h fluid restriction and 2-h EXDE to -4% body mass, then were rehydrated to -2% body mass in a randomized, cross-over design. REHY methods included no fluid (NF), ad libitum, oral, intravenous (IV), and a combination of IV and OR (IV+OR) of ½-normal saline (0.45% NaCl). REHY occurred for 30min and subjects were observed during rest for 30min following. Seated, standing, and mean arterial pressure (MAP) and blood pressure (BP) were measured every 15min throughout REHY. Heart rate (HR), plasma arginine vasoporessin concentration [AVP], and thirst perception were measured throughout REHY. EXDE resulted in a body mass loss of 4.32 ± 0.22%. REHY returned subjects to -2.13 ± 0.47% body mass for controlled trials. Seated systolic BP was greater for IV+OR compared to oral (p=.015). Seated systolic BP and MAP during REHY showed IV+OR were greater than oral, independent of time (p≤.011). Upon standing, IV+OR demonstrated greater BP than both NF (p=.012) and oral (p=.031). HR was reduced by IV and IV+OR by a greater extent than NF at REHY30 and REHY60 (p<.05). IV+OR [AVP] demonstrated a strong trend for decreasing over time (p=.054) and was significantly less than NF at REHY60 (p=.003). Practical application seeking to restore cardiovascular function following EXDE, the combined use of IV+OR rather than a single REHY method seems to be most expedient.
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