Effect of carbohydrate ingestion on sprint performance following continuous and intermittent exercise.
OBJECTIVE
This investigation was conducted to study the effects on sprint performance of glucose and fructose ingestion during a 15-min rest period half way through 90 min of continuous and intermittent exercise. On three occasions, eight subjects cycled at 76 +/- 2% VO2max for 90 min (continuous trials: CON trials) with a 15-min half-time break.


METHODS
On another three occasions, they cycled for 90 min between moderate (65% VO2max) and high (100% VO2max) intensity (intermittent trials: INT trials) with the same half-time. In both trials, 90-min exercise was followed by a 40-s Wingate test to evaluate remaining sprint capacity. During half-time, they consumed either 20% glucose polymer (G), 20% fructose (F) or sweet placebo (P). Ingestion of G maintained plasma glucose levels, carbohydrate oxidation rate and lower value of ratings of perceived exertion (RPE) in both trials and indicated higher sprint performance compared with P (mean power of CON trials: 614.3 +/- 23.3 W vs 574.0 +/- 22.7 W, P < 0.001, INT trials: 629.5 +/- 27.6 W vs 596.3 +/- 25.5 W, P < 0.01).


RESULTS
Ingestion of F showed similar effect in CON trials (603.8 +/- 26.1 W vs 574.0 +/- 22.7 W, P < 0.01) but had no positive effect in INT trials. Additionally, mean power of G was higher than F (629.5 +/- 27.6 W vs 598.4 +/- 34.2 W, P < 0.01) in INT trials.


CONCLUSIONS
These results indicated that ingestion of G during half-time of 90-min exercise could maintain carbohydrate utilization and improve sprint performance in both CON and INT trials.
Sugiura
K
K
Department of Life Science, Graduate School of Arts and Science, University of Tokyo, Japan.
Kobayashi
K
K
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D005080:Exercise Test / Q000379:methods; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005632:Fructose / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D005990:Glycerol / Q000097:blood; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007773:Lactates / Q000097:blood; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D010465:Perception / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D010919:Placebos; D012420:Running / Q000502:physiology*; D013997:Time Factors
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D007773:Lactates; D010919:Placebos; D005632:Fructose; D005947:Glucose; D005990:Glycerol