TY - JOUR
T1 - Blood glucose responses to carbohydrate feeding prior to exercise in the heat
T2 - Effects of hypohydration and rehydration
AU - Echegaray, M.
AU - Armstrong, L. E.
AU - Maresh, C. M.
AU - Riebe, D.
AU - Kenefick, R. W.
AU - Castellani, J. W.
AU - Kavouras, S.
AU - Casa, D.
PY - 2001/1/1
Y1 - 2001/1/1
N2 - This study assessed the plasma glucose (PG) and hormonal responses to carbohydrate ingestion, prior to exercise in the heat, in a hypohydrated state versus partial rehydration with intravenous solutions. On separate days, 8 subjects (21.0 ± 1.8 years; 57.3 ± 3.7 ml · kg-1 min-1) exercised at 50% V̇O2max in a 33 °C environment until a 4% body weight loss was achieved. Following this, subjects were rehydrated (25 ml · kg-1) with either: 0.45% IV saline (45IV), 0.9% IV saline (9IV), or no fluid (NF). Subjects then ingested 1 g · kg-1 of carbohydrate and underwent an exercise test (treadmill walking, 50% V̇O2max, 36 °C) for up to 90 min. Compared to pre-exercise level (294 mg · dl-1), PG increased significantly (>124 mg · dl-1) at 15 min of the exercise test in all trials and remained significantly elevated for 75 min in NF, 30 min more than in the 2 rehydration trials. Although serum Insulin increased significantly at 15 min of exercise in the 45IV trial (7.2 ± 1.2 vs. 23.7 ± 4.7 μIU · ml-1), no significant differences between trials were observed. Peak plasma norepinephrine was significantly higher in NF (640 ± 66 pg · ml-1) compared to the 45IV and 9IV trials (472 ± 55 and 474 ± 52 pg · ml-1, respectively). In conclusion, ingestion of a small solid carbohydrate load prior to exercise in the 4% hypohydration level resulted in prolonged high PG concentration compared to partial IV rehydration.
AB - This study assessed the plasma glucose (PG) and hormonal responses to carbohydrate ingestion, prior to exercise in the heat, in a hypohydrated state versus partial rehydration with intravenous solutions. On separate days, 8 subjects (21.0 ± 1.8 years; 57.3 ± 3.7 ml · kg-1 min-1) exercised at 50% V̇O2max in a 33 °C environment until a 4% body weight loss was achieved. Following this, subjects were rehydrated (25 ml · kg-1) with either: 0.45% IV saline (45IV), 0.9% IV saline (9IV), or no fluid (NF). Subjects then ingested 1 g · kg-1 of carbohydrate and underwent an exercise test (treadmill walking, 50% V̇O2max, 36 °C) for up to 90 min. Compared to pre-exercise level (294 mg · dl-1), PG increased significantly (>124 mg · dl-1) at 15 min of the exercise test in all trials and remained significantly elevated for 75 min in NF, 30 min more than in the 2 rehydration trials. Although serum Insulin increased significantly at 15 min of exercise in the 45IV trial (7.2 ± 1.2 vs. 23.7 ± 4.7 μIU · ml-1), no significant differences between trials were observed. Peak plasma norepinephrine was significantly higher in NF (640 ± 66 pg · ml-1) compared to the 45IV and 9IV trials (472 ± 55 and 474 ± 52 pg · ml-1, respectively). In conclusion, ingestion of a small solid carbohydrate load prior to exercise in the 4% hypohydration level resulted in prolonged high PG concentration compared to partial IV rehydration.
KW - Catecholamines
KW - Dehydration
KW - Insulin
KW - Intravenous-saline
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U2 - 10.1123/ijsnem.11.1.72
DO - 10.1123/ijsnem.11.1.72
M3 - Article
C2 - 11255138
AN - SCOPUS:0035089034
VL - 11
SP - 72
EP - 83
JO - International Journal of Sport Nutrition and Exercise Metabolism
JF - International Journal of Sport Nutrition and Exercise Metabolism
SN - 1526-484X
IS - 1
ER -