Carbohydrate Intake Does Not Change Muscle Energy Use or Performance in Short, Intense Interval Exercise

Carbohydrate supplementation (CHO, ~55 g/h) showed no effect on muscle glycogen breakdown or sprint performance during high-intensity intermittent exercise.

• No significant differences were found in muscle glycogen depletion between carbohydrate and placebo conditions.
• Post-exercise whole-muscle glycogen concentrations were similar for both conditions, with values of 146 ± 20 and 122 ± 15 mmol·kgdw.
• Repeated sprint ability declined by approximately 9% after the final exercise period, with no differences between carbohydrate and placebo conditions.
• Blood glucose levels were significantly higher in the carbohydrate condition (5.3 ± 0.2 mmol·L) compared to the placebo (4.1 ± 0.2 mmol·L).
• Plasma insulin levels were fivefold higher in the carbohydrate condition, indicating an increase in insulin response.
• These findings suggest that carbohydrate supplementation may not enhance performance in short-duration, high-intensity intermittent sports.

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