Last updated: 3 October 2026
Reviewed by Jordan Morley, FA Level 2 Football Coach
Carbohydrate loading (glycogen supercompensation) involves consuming a high-carbohydrate diet (8-12g/kg bodyweight/day) for 2-3 days before an endurance event to maximise muscle and liver glycogen stores. Effective for events lasting more than 90 minutes (marathon, 70.3, cycling gran fondo). A 70kg athlete carb-loading at 10g/kg needs 700g carbohydrates per day. Modern protocols combine a depletion run 2-3 days before the event with 2-3 days of high-carb intake. Not beneficial for events under 60-75 minutes.
- 8-12g carbohydrate per kg bodyweight per day
- 2-3 days before event
- Effective for 90+ minute events
- Not beneficial for short events under 60-75 min
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Carb-loading — deliberately increasing carbohydrate intake in the 1-3 days before a long endurance event — aims to maximize glycogen stores beyond their normal capacity, giving an athlete a larger fuel reserve for events lasting 90+ minutes where glycogen depletion is a realistic limiting factor, though it offers little to no benefit for shorter events where glycogen stores wouldn't be fully depleted anyway.
FAQ
How long before an event should carb-loading start?
Most protocols recommend increasing carbohydrate intake for 1-3 days before a long endurance event, often alongside reduced training volume (tapering) to maximize glycogen storage.
Is carb-loading necessary for shorter events?
Generally no — carb-loading's benefit comes from maximizing glycogen stores for events where depletion is a realistic limiting factor (typically 90+ minutes); shorter events don't deplete glycogen enough to benefit meaningfully from the strategy.