Effect of preexercise glycemic-index meal on running when CHO-electrolyte solution is consumed during exercise.
OBJECTIVE
This study examined the effect of consuming carbohydrate- (CHO) electrolyte solution on running performance after different-glycemic-index (GI) meals.


METHODS
Nine men completed 3 trials in a randomized counterbalanced order, with trials separated by at least 7 days. Two hours before the run after an overnight fast, each participant consumed a high-GI (GI = 83) or low-GI (GI = 36) CHO meal or low-energy sugar-free Jell-O (GI = 0, control). The 2 isocaloric GI meals provided 1.5 g available CHO/kg body mass. During each trial, 2 ml/kg body mass of a 6.6% CHO-electrolyte solution was provided immediately before exercise and every 2.5 km after the start of running. Each trial consisted of a 21-km performance run on a level treadmill. The participants were required to run at 70% VO2max during the first 5 km of the run. They then completed the remaining 16 km as fast as possible.


RESULTS
There was no difference in the time to complete the 21-km run (high-GI vs. low-GI vs. control: 91.1 +/- 2.0 vs. 91.8 +/- 2.2 vs. 92.9 +/- 2.0 min, n.s.). There were no differences in total CHO and fat oxidation throughout the trials, despite differences in preexercise blood glucose, serum insulin, and serum free-fatty-acid concentrations.


CONCLUSIONS
When a CHO-electrolyte solution is consumed during a 21-km run, the GI of the preexercise CHO meal makes no difference in running performance.
Wong
Stephen H S
SH
Department of Sports Science, Chinese University of Hong Kong, Shatin, Hong Kong.
Chan
Oi Won
OW
Chen
Ya Jun
YJ
Hu
Heng Long
HL
Lam
Chin Wan
CW
Chung
Pak Kwong
PK
D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000145:classification / Q000378:metabolism; D004573:Electrolytes / Q000008:administration & dosage* / Q000378:metabolism; D038321:Glycemic Index; D006801:Humans; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000187:drug effects / Q000502:physiology*; D012420:Running / Q000502:physiology*; D055815:Young Adult
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004573:Electrolytes; D007328:Insulin; D019344:Lactic Acid