The Tour de France is the ultimate testing ground for endurance. Every year, times get faster, power outputs climb, and the science of human performance takes another leap forward. But the most dramatic gains in the last five years aren’t just from better bikes or tougher training. They’re coming from a quiet revolution in how athletes fuel their bodies.

Take this year’s Tour winner, Tadej Pogačar. He finished roughly two minutes faster than Lance Armstrong’s peak-era time — despite stricter anti-doping controls. What’s changed? Fuel. Top athletes are using smarter, science-backed fueling strategies that give them more usable energy than ever before. Before we get into the nitty-gritty, it's important to understand what carbohydrates can do for our bodies and peak performance. it's important to understand what carbohydrates can do for our bodies and peak performance 

Carbohydrates, think pasta, potatoes, rice, whole-grain bread, all break down into glucose, the body’s main energy currency. During exercise, your muscles use glucose as a fuel source to make ATP (energy), powering each pedal stroke, stride, or swim stroke. The more efficiently you supply glucose, the longer and harder your muscles can go. 

For years, sports scientists believed the body could only absorb 30–60 grams of glucose per hour during exercise, and this was a tried and tested upper limit. Take in more than that and your gut revolts, cue the mid-race dash to the porta-loo. This “ceiling” was thought to be ironclad. 

Fructose: the game changer

Then researchers discovered something huge: fructose (a different form of carbohydrate) uses an entirely separate transport system in the gut. By pairing glucose and fructose, athletes could double their carbohydrate intake, up to about 120 grams per hour (a limit achieved by only the top athletes). This has reshaped fueling strategies and is pushing elite endurance races and their athletes to new limits.  

Before you grab a 120-gram carb mix, know this: athletes like Tadej Pogačar didn’t just switch overnight. They trained their guts—gradually increasing glucose and fructose intake over months—so their digestive systems could tolerate the load. It turns out the gut can be trained just like a muscle can! This gut training, plus careful nutrition, such as prebiotic complexes between races, helps them perform without wrecking their microbiome. 

Gut health matters 

Mega-doses of carbs can stress your gut, so elite athletes often supplement with probiotics or gut-support products to restore balance. Keeping your microbiome healthy not only helps you tolerate more carbs but also supports recovery and long-term health.  

Putting it all together 

If you’re training for a marathon or a long endurance race, think of fueling as part of your training plan. Just as you build mileage slowly, increase your carb intake gradually to find your personal sweet spot. With time, your gut adapts, your energy stays stable, and your recovery improves. But remember, these carbohydrate sources must contain both glucose and fructose if you want to push those boundaries.  

Performance Proven on the Road: up4™ Energy Products 

Our up4™ Isotonic Energy Mix and up4™ Energy Gels aren’t just theory — they’re proven in the peloton. In partnership with Team Picnic PostNL, these products have been tested and refined under the toughest conditions: training camps, stage races, and ultimately the Tour de France itself. 

The team’s riders relied on the same glucose + fructose blend you’ll find in every up4™ mix and gel to power explosive climbs, long transfers, and day-after-day endurance. Their feedback helped us perfect a formula that’s fast to absorb, gentle on the gut, and reliable mile after mile. 

Now you can experience the same pro-tested fueling strategy. Whether you’re training for your first sportive, a marathon, or just want to power your weekend rides, up4™ Energy products bring Tour de France science to your bottle and your pocket, so you can go further, recover faster, and train smarter. 

The high-carb fueling revolution shows how far science has come—but it also shows that fueling is highly individual. Start with evidence-based guidelines, listen to your body, and train your gut as carefully as you train your muscles. On race day, you’ll feel stronger, last longer, and finish faster.