British journal of sports medicineOct 17, 1998

Carbohydrate-electrolyte drink may improve endurance during long, repeated intense runs

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Updated Apr 2, 2026

Abstract

Performance times during endurance running were similar for both the water placebo and 6.9% carbohydrate-electrolyte solution trials, averaging 111.4 minutes.

There was no significant difference in performance times between the water placebo and carbohydrate-electrolyte solution trials.
Blood glucose levels were higher at 40 minutes in the carbohydrate trial compared to the placebo.
The total carbohydrate oxidation rates did not differ between the two trials.
These findings suggest that the carbohydrate-electrolyte solution may not influence fatigue onset during intermittent high-intensity running.

Simplified

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.

CONCLUSION: 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.

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Carbohydrate-electrolyte drink may improve endurance during long, repeated intense runs

Abstract

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