Effect of a carbohydrate-electrolyte drink on endurance capacity during prolonged intermittent high intensity running.
OBJECTIVE
To examine the effect of a carbohydrate-electrolyte solution on endurance capacity during prolonged intermittent running.


METHODS
Nine subjects (eight men and one woman) ran to exhaustion on a motorised treadmill on two occasions separated by at least 10 days. After an overnight fast, they performed repeated 15 second bouts of fast running (at 80% Vo2MAX for the first 60 minutes, at 85% Vo2MAX from 60 to 100 minutes of exercise, and finally at 90% Vo2MAX from 100 minutes of exercise until exhaustion), separated by 10 seconds of slow running (at 45% Vo2MAX). On each occasion they drank either a water placebo (P) or a 6.9% carbohydrate-electrolyte (CHO) solution immediately before the run (3 ml/kg body mass) and every 20 minutes thereafter (2 ml/kg body mass).


RESULTS
Performance times were not different between the two trials (112.5 (23.3) and 110.2 (21.4) min for the P and CHO trials respectively; mean (SD)). Blood glucose concentration was higher in the CHO trial only at 40 minutes of exercise (4.5 (0.6) v 3.9 (0.3) mmol/1 for the CHO and P trials respectively; p < 0.05), but there was no difference in the total carbohydrate oxidation rates between trials.


CONCLUSIONS
These results suggest that drinking a 6.9% carbohydrate-electrolyte solution during repeated bouts of submaximal intermittent high intensity running does not delay the onset of fatigue.
Department of Physical Education, Sports Science, and Recreation Management, Loughborough University, United Kingdom.
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Nassis
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D000328:Adult; D001628:Beverages; D001786:Blood Glucose / Q000032:analysis; D001823:Body Composition; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism; D004311:Double-Blind Method; D004326:Drinking; D004573:Electrolytes / Q000008:administration & dosage* / Q000378:metabolism; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005215:Fasting; D005221:Fatigue / Q000503:physiopathology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007773:Lactates / Q000097:blood; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D010465:Perception; D010807:Physical Endurance / Q000502:physiology*; D010919:Placebos; D012420:Running / Q000502:physiology*; D013546:Sweating / Q000502:physiology; D013997:Time Factors; D014867:Water / Q000008:administration & dosage
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004573:Electrolytes; D007773:Lactates; D010919:Placebos; D014867:Water