High‐intensity exercise and muscle glycogen availability in humans

Glycogen concentration in muscle was significantly lower following a low-carbohydrate diet compared to a high-carbohydrate diet.

• Lower muscle glycogen (180 and 181 mmol/kg) was associated with significantly reduced performance in high-intensity intermittent exercise compared to higher glycogen levels (397 and 540 mmol/kg).
• In long-duration intermittent exercise, the number of completed exercise bouts increased by 265% with higher glycogen availability.
• At fatigue during prolonged exercise, glycogen concentration was significantly lower after low-carbohydrate intake compared to high-carbohydrate intake (58 vs. 181 mmol/kg).
• Plasma concentrations of adrenaline, nor-adrenaline, free fatty acids, and glycerol increased several-fold above resting values with both dietary conditions.
• Oxygen uptake during prolonged exercise periods approached 70% of maximum oxygen consumption.

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