Hitting the dreaded "wall" during a long run or marathon is every runner's worst nightmare. That sudden, brick-wall fatigue happens when your body completely runs out of glycogen—its primary, fast-burning fuel source.
Whether you're tackling your first 15k or aiming for a marathon PB, mastering your fueling strategy is just as important as putting in the miles. Here is the complete breakdown of how to fuel before, during, and after your long runs.
Phase 1: Pre-Run (Top Up the Tank)
Your body naturally stores around 1,500 to 2,000 calories worth of glycogen in your muscles and liver. Your job before a long effort is to top off those stores without upsetting your stomach.
- Carb-Loading (2–3 Days Out): For races lasting longer than 90 minutes, shift your meal proportions so that 70–80% of your daily calories come from simple carbohydrates. Keep fibre, heavy fats, and massive portions of protein low to avoid feeling bogged down.
- The Morning Meal (2–3 Hours Before): Consume 1–2 grams of easy-to-digest carbs per kilogram of body weight.
- Go-To Breakfasts: Oatmeal with syrup and a banana, white toast with jam, or a plain bagel. Avoid high-fibre grains, dairy, or heavy bacon that digest slowly.
Phase 2: Intra-Run (Fuel On the Move)
Once you pass the 75-minute mark, your internal carbohydrate stores drop drastically. You need to supply steady energy to keep your pace steady.
Hourly Targets:
- 1 to 2 Hour Runs: 30g – 60g of carbs per hour
- 2+ Hours / Marathon: 60g – 90g of carbs per hour
- Start Early: Don't wait until you're exhausted to start fueling. Take your first gel 25 to 30 minutes in, and repeat at consistent intervals (every 20 to 30 minutes). Sometimes I'll take a gel 15 minutes before a run as well.
- Dual-Source Carbs: For high intake (60g+ per hour), pick gels or drinks that use a 2:1 ratio of Glucose/Maltodextrin to Fructose. This allows your gut to absorb carbohydrates through two separate pathways at once without overloading your stomach.
- Hydrate Smart: Aim for 400–800ml of fluid and ~300–500mg of sodium per hour depending on heat and sweat rate. Pro-tip: Always wash down energy gels with plain water, not sugary sports drink, to prevent an upset stomach.
Phase 3: Post-Run (Rebuild and Replenish)
The first 30 to 60 minutes after finishing is your optimal recovery window, when your muscles act like sponges for nutrients.
- The 4:1 Ratio: Aim for a 3:1 or 4:1 ratio of carbohydrates to protein (roughly 60g of carbs to 20g of protein). The carbs restock depleted glycogen, while the protein immediately kicks off muscle repair.
- Quick Fixes: Chocolate milk, a fruit smoothie with protein powder, or a bagel with eggs.
The Golden Rule: Train Your Gut
Your stomach is a muscle that needs training just like your legs. Never try a new gel, drink mix, or breakfast on race day. Use your weekly long runs to test your nutrition strategy at actual race pace so your digestive system gets used to processing sugars under physical stress. What to test? Different products, flavours, caffeine, and quantities! The more you practise the more your gut will adapt and be able to absorb more of what you are consuming.