TY - JOUR
T1 - Rehydration with glycerol
T2 - Endocrine, cardiovascular, and thermoregulatory responses during exercise in the heat
AU - Kavouras, Stavros A.
AU - Armstrong, Lawrence E.
AU - Maresh, Carl M.
AU - Casa, Douglas J.
AU - Herrera-Soto, Jorge A.
AU - Scheett, Timothy P.
AU - Stoppani, James
AU - Mack, Gary W.
AU - Kraemer, William J.
PY - 2006/2
Y1 - 2006/2
N2 - The impact of rehydration with glycerol on cardiovascular and thermoregulatory responses during exercise in the heat was studied in eight highly trained male cyclists. Each subject completed three dehydration-rehydration experimental trials that differed only in the rehydration treatment, each separated by 7 days. Before each experimental day, subjects dehydrated to -4% of their body weight by exercise and water restriction. The experimental treatments were as follows: no fluid (NF), glycerol bolus (1 g/kg body wt) followed by water (G), and water alone (W). Rehydration (3% body weight) was given over an 80-min period. After rehydration, subjects cycled (74% peak O2 uptake) to exhaustion in a hot and wet (37°C and 48% relative humidity) environment. For G, plasma volume was expanded (P < 0.05) during rehydration and remained higher than W (P < 0.05) during exercise. Exercise time to exhaustion during G (33±4 min) was longer (P<0.05) compared with bothW(27±3 min) and NF (19 ± 3 min). Cutaneous vascular conductance was significantly elevated (P < 0.05) during G, but G provided no other thermoregulatory or cardiovascular benefits compared with W and NF. Fluid-regulating hormones (vasopressin, aldosterone, atriopeptin, and plasma renin activity) decreased during rehydration and increased during exercise (except atriopeptin), but there were no differences between G and W. These data indicated that glycerol had little or no major effect on fluid-regulating factors during rehydration or exercise, and the improved exercise capacity in G was likely due to a greater plasma volume during exercise.
AB - The impact of rehydration with glycerol on cardiovascular and thermoregulatory responses during exercise in the heat was studied in eight highly trained male cyclists. Each subject completed three dehydration-rehydration experimental trials that differed only in the rehydration treatment, each separated by 7 days. Before each experimental day, subjects dehydrated to -4% of their body weight by exercise and water restriction. The experimental treatments were as follows: no fluid (NF), glycerol bolus (1 g/kg body wt) followed by water (G), and water alone (W). Rehydration (3% body weight) was given over an 80-min period. After rehydration, subjects cycled (74% peak O2 uptake) to exhaustion in a hot and wet (37°C and 48% relative humidity) environment. For G, plasma volume was expanded (P < 0.05) during rehydration and remained higher than W (P < 0.05) during exercise. Exercise time to exhaustion during G (33±4 min) was longer (P<0.05) compared with bothW(27±3 min) and NF (19 ± 3 min). Cutaneous vascular conductance was significantly elevated (P < 0.05) during G, but G provided no other thermoregulatory or cardiovascular benefits compared with W and NF. Fluid-regulating hormones (vasopressin, aldosterone, atriopeptin, and plasma renin activity) decreased during rehydration and increased during exercise (except atriopeptin), but there were no differences between G and W. These data indicated that glycerol had little or no major effect on fluid-regulating factors during rehydration or exercise, and the improved exercise capacity in G was likely due to a greater plasma volume during exercise.
KW - Cycling
KW - Fluid balance
KW - Osmoregulation
KW - Plasma volume
KW - Vasopressin
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U2 - 10.1152/japplphysiol.00187.2005
DO - 10.1152/japplphysiol.00187.2005
M3 - Article
C2 - 16210441
AN - SCOPUS:33646346662
SN - 8750-7587
VL - 100
SP - 442
EP - 450
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 2
ER -