Drinks, Gels or bars?


During a marathon, 60 to 75 per cent of your fuel comes from carbs, and the remainder from fat. For a half marathon, when you’re running faster, you use even more carbs. Carb stores, which are made up of glycogen, give you the ability to move. But they’re limited, lasting about an hour for hard efforts and two hours for a slower pace. At this point, you’ll start running on empty, which causes your blood sugar levels (glucose) to plummet. That’s when you hit the wall. Taking in quick carbs – gels, chews, and sports drinks – will keep your glucose levels stable, allowing you to keep moving forward (somewhat) comfortably.

Caffeine may help. Aim for 30 to 50mg (gels and chews typically have 20 to 50mg per serving) a little more than halfway through your run. The kick can help make the effort feel easier.

Swish and Spit

Rinse your mouth with a sip of sports drink for about 15 seconds before spitting it out. This will alert your brain to the presence of carbs, lowering your perceived sense of exertion.

Fuelling tips

Bearing the above in mind, what does this mean for your own fuelling?

During harder workouts or races, stick to drinks and gels rather than using energy bars. During longer, less intense efforts when you crave something more substantial than drinks/gels, an energy bar can be a good choice, but choose one with a low fat content (under 10%).

When using bars or gels, don't forget to consume extra plain water, especially in warm conditions. If you have a particularly sensitive tummy, choose carbohydrate drinks rather than bars or gels for energy replacement.