A few years ago, it was considered impossible to consume more than 60–90 grams of carbohydrates per hour during a competition. Those attempting more risked stomach problems and a drop in performance. Today, top athletes report very different figures: the current Ironman winner in Nice, Casper Stornes, consumed over 180 grams of carbohydrates per hour to himself – and was thus able to maintain his performance at the highest level.
How is this possible? And what's behind this development?
Why carbohydrates are key
During intense exercise, carbohydrates are the most important fuel. Fat provides energy, but much more slowly. Muscle and liver glycogen only lasts for a few hours—if you don't replenish it in time, you'll experience the dreaded "starvation bout." A high carbohydrate intake stabilizes performance, prevents depletion, and accelerates recovery.
From the limit to the new reality: What has changed
For a long time it was assumed that the intestine could only absorb around 60 g of carbohydrates per hour – because at that time people focused exclusively on glucose.
Today we know:
-
Glucose is transported via the transporter SGLT1 recorded.
-
Fructose uses the transporter GLUT5.
By combining both types of sugar (e.g., in a ratio of 1:0.8), much higher absorption rates can be achieved. For example, 120–150 g/h is feasible for many athletes—and with targeted training, even up to 180 g/h.
Train the Gut – train the intestines
High carbohydrate intake doesn't work overnight. The gut needs to be trained just like the muscles and cardiovascular system.
The strategy:
-
Consume carbohydrates regularly during training.
-
Start with moderate amounts (e.g. 80–90 g/h) and increase gradually.
-
Constant supply: Eat smaller portions every 10-15 minutes instead of large amounts at once.
-
Prefer liquid energy sources such as gels or drinks as they are easier to digest.
Over time, the body adapts: transport proteins are upregulated, gastric emptying improves, and symptoms decrease.
The role of modern sports nutrition
In addition to our understanding of the transport mechanisms, the products themselves have also taken a leap forward. New sports drinks and gels combine glucose and fructose in optimal ratios, often in the form of maltodextrin-fructose blends. This has made high intake practical for the first time.
Conclusion
It's no coincidence that today's top triathletes, like those competing at Ironman Nice, can consume 180g of carbohydrates per hour. It's the result of:
-
Better understanding of physiology
-
Targeted intestinal training (“train the gut”)
-
Perfectly balanced sports nutrition
The good news: These strategies aren't just for pros. Even ambitious amateurs can gradually increase their carbohydrate intake—and thereby become more powerful, more stable, and faster.