Effect of acute prior exercise on glycemic and insulinemic indices.
BACKGROUND
Acute exercise is associated with increased insulin sensitivity characterized by increased insulin-induced glucose transport for periods of up to 48 h after the bout of exercise. This suggests that the glycemic response to a meal may be altered by prior exercise.


OBJECTIVE
We tested the hypothesis that the glycemic and insulinemic responses to a test food consumed following exercise would be lower than when consumed without prior exercise.


METHODS
Four lean males (age: 27 +/- 4 y) and 4 females (age: 23 +/- 3 y) completed 3 experimental conditions in random order: ExCHO-Subjects exercised on a cycle ergometer at 70% VO2peak with a net energy cost of 400 kcal, which was followed by consumption of a high carbohydrate (CHO) energy bar; NoExCHO-Same as ExCHO except subjects sat quietly rather than exercised; and NoExGlc-Same as NoExCHO except subjects consumed a 50 g glucose (glc) drink as the reference CHO for GI and insulinemic index (II) determination. For each condition, following exercise or rest, baseline venous blood samples were obtained. Postprandial blood samples were obtained at 15 min intervals for 2 h.


RESULTS
Neither the 2-h glucose area under the curve (AUC) or the GI were different between ExCHO and NoExCHO. The insulin AUC for ExCHO was 28% lower than the insulin AUC for NoExCHO (p = 0.03). The calculated II for the ExCHO condition was 30% lower than that of NoExCHO (p = 0.05).


CONCLUSIONS
An acute bout of prior exercise had no effect on the GI of an energy bar compared to that of the same food determined under the standard no-exercise conditions. However, prior exercise resulted in a lower 2-h insulin response to the CHO-rich energy bar.
Englert
Virginia
V
Department of Food Science and Human Nutrition, Nutrition and Metabolic Fitness Laboratory, Colorado State University Fort Collins, CO 80523, USA.
Wells
Katherine
K
Long
Wiley
W
Hickey
Matthew S
MS
Melby
Christopher L
CL
D000328:Adult; D019540:Area Under Curve; D001481:Basal Metabolism / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism*; D018592:Cross-Over Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D008297:Male; D019518:Postprandial Period
D001786:Blood Glucose; D007328:Insulin