Endurance runs — whether 90 minutes, a marathon, or beyond — are not just a test of fitness. They’re a test of how well you fuel your body. Smart fueling means knowing when, what, and how much to eat and drink to maximize performance without causing stomach issues.

Why Fueling Matters

Glycogen is limited: Muscles store ~90–120 minutes worth of carbohydrates. After that, energy drops sharply.

Fuel prevents “the wall”: Consuming carbs during runs keeps blood sugar stable, sparing glycogen and delaying fatigue.

Hydration matters too: Even mild dehydration (2% body weight lost) reduces endurance and focus.

Smart fueling = carbs + fluids + electrolytes.

Pre-Run Fueling

Night before: Carb-rich, moderate protein, low fat, low fiber (e.g., pasta with tomato sauce, rice bowl).

2–3 hours before: Balanced meal, ~1–4 g carbs per kg body weight.

30–60 minutes before: Quick snack if needed (banana, toast with jam, energy bar).

Hydration: 400–600 ml water 2–3 hrs before; small sips just before starting.

Fueling During the Run

Carbohydrates:

30–60 g carbs per hour (most runners).

Up to 90 g/hour for marathons & ultras with glucose + fructose blends.

Sources: Energy gels, chews, sports drinks, bananas, dates.

Timing: Start fueling 30–45 minutes in, then every 30–40 minutes.

Fluids

400–800 ml/hour, depending on sweat rate and climate.

Drink steadily, not all at once.

Electrolytes

Sodium is key (lost most in sweat).

Aim for 300–600 mg sodium/hour in long or hot runs.

Use electrolyte drinks, tabs, or gels with added sodium.

Smart Fueling Tips

Train your gut: Practice fueling in long runs so your body adapts to digesting carbs while running.

Mix sources: Gels + drinks + small bites reduce flavor fatigue and stomach stress.

Avoid overload: Don’t take too much at once; spread carbs evenly.

Personalize: Sweat rates, stomach tolerance, and pace all vary — experiment in training.

Post-Run Refueling

Carbs + Protein: Within 30–60 minutes, aim for 3:1 ratio (carbs:protein).

Example: smoothie with banana + yogurt, or rice with chicken.

Rehydrate: Replace fluids + electrolytes lost in sweat.

Micronutrients: Include fruits, veggies, and whole foods for vitamins and minerals that aid recovery.

Smart fueling for endurance runs is simple but powerful:

Before: Load glycogen with carbs + hydrate.

During: 30–60 g carbs/hour, steady fluids, electrolytes.

After: Replenish, repair, and rehydrate.

Fueling wisely turns endurance runs from survival mode into strong, sustained performances. The right fuel at the right time = more miles, less fatigue, better results.