Gels, chews or real food? Fuelling the long run

Once a run goes past 75–90 minutes, your stored glycogen starts to run low. Taking in carbohydrate during the run keeps your pace steady and, just as importantly, keeps your head clear in the last kilometres.

How much per hour

Most runners do well with 30–60 g of carbohydrate per hour. Experienced marathoners who have trained their gut often go up to 80–90 g using products that mix glucose and fructose. Start low and build up over several weeks.

The options

• Gels — about 20–30 g each, easy to carry, need water.
• Chews — easier to take in small bites, slower to eat while breathing hard.
• Sports drink — carbs and fluid together, but you need access to it.
• Real food — dates, boiled potatoes with salt, rice balls. Great for slow long runs and trails.

Train your gut

The stomach adapts like any muscle. Practise race fuelling on every long run: same product, same timing. Begin 30–40 minutes into the run and then take something every 20–30 minutes rather than waiting until you feel empty.

Rule of thumb: nothing new on race day — not the gel, not the shoes, not the breakfast.

Fluids and salt

Drink to thirst on most days. In heat, or if you are a heavy sweater (white salt marks on your cap), add an electrolyte drink or a salt tablet. Drinking large amounts of plain water for hours without salt is not helpful and can be risky.

General information for healthy adults, not medical advice. See our disclaimer.