Pre-Race Carbohydrate Loading: A Modern, Simplified Version Replaces the Painful Depletion Method

Why Carbohydrate Loading Matters

Muscle and liver glycogen are the primary fuel for high-intensity endurance, totaling only about 1,800–2,500 kcal—the root cause of hitting the wall in long-distance events. Carbohydrate loading manipulates pre-race nutrition to raise muscle glycogen concentrations from a normal 100–120 mmol/kg to 150–200+ mmol/kg, delaying fatigue and improving late-race performance in events lasting longer than 90 minutes.

From the Painful Old Method to the Streamlined New Approach

• Classic Astrand method (1960s): First 3 days of high-intensity training plus a low-carb “depletion” phase to empty glycogen, then 3 days of high-carb “rebound” supercompensation. Problem: the depletion phase causes extreme fatigue, increased susceptibility to illness and injury, and low mood—a disaster for form and morale.
• Modern streamlined method: Research shows trained athletes don’t need the miserable depletion phase at all. In the 36–48 hours before race day, combined with training taper, simply raising carbohydrate intake to 10–12 g/kg body weight/day achieves equal or even higher muscle glycogen concentrations.

Practical Details

• Dosage: 1–2 days before race day, 10–12 g/kg body weight/day of carbohydrates (a 70 kg athlete needs 700–840 g/day).
• Combine with taper: Drastically reduce training volume to avoid burning off the glycogen you’ve loaded.
• Choose low-residue, high-carb foods: White rice, white bread, potatoes, sports drinks, fruit juice—reduce fiber to avoid bloating and multiple bathroom trips on race day.
• Hydration: Every 1 g of stored glycogen binds about 3 g of water, so loading causes a 1–2 kg weight gain and a slightly puffy feeling—this is normal and beneficial (extra water).

Who Needs It, Who Doesn’t

• Needed for: Continuous high-intensity events lasting >90 minutes (marathons, long-distance triathlon, Gran Fondo, endurance trail racing).
• Limited benefit for: Events under 60–75 minutes—glycogen stores are already sufficient, and loading only adds unnecessary weight.

Race-Day Breakfast Transition

After loading, eat a high-carb breakfast (1–4 g/kg, low-fiber, easily digestible) 3–4 hours before the start to refill glycogen used overnight and stabilize blood sugar. Small amounts of fuel within the hour before the start require individual testing to avoid reactive hypoglycemia.

Never Try It for the First Time on Race Day

High-carb loading changes bowel habits and how you feel, so be sure to do a full rehearsal during a simulation race in your training cycle to confirm your gut and weight changes are acceptable.

Filling your glycogen tank no longer requires three days of hellish depletion. The modern approach is simply: eat rice generously for two days before the race, put your training away, and accept the slight water-retention weight gain—simple, painless, and scientifically more reliable.

Related Reading

• The Science of Carbohydrate Loading: How to Properly Carbo-Load Before a Race
• Pre-Race Glycogen Loading: The Modern Version Needs No Depletion Phase—A Coach’s Guide to Calculating Your Per-Kilogram Carb Dosage
• Carb-Loading Three Days Before a Race: Complete Plan and Practical Template
• Carb Loading Three Days Before a Race: The Modern Simplified Protocol