Current fueling guidelines for endurance athletes recommend up to ~90 grams of carbohydrates per hour during long, intense sessions. However, emerging lab research shows that some athletes are capable of oxidizing significantly more than this.
The challenge is that these tests aren’t widely available yet, and results don’t always hold up in real-world settings — making it difficult for athletes to know how many carbohydrates they should be consuming.
One semi-pro triathlete, Riccardo Raso, managed to find his optimal carbohydrate intake through a careful and strategic approach — combining lab assessments, long-session experimentation, pre-race simulations, and continuous feedback.
Here’s how he did it.
Combining Lab Data and Field Testing
As a semi-pro triathlete, I undergo metabolic assessments roughly every six months (previously every 3–4 months when I was training at a higher volume and competitive level).
These tests provide objective data on substrate utilization, including carbohydrate oxidation rates at different intensities and how my fuel mix shifts as intensity increases.
Important note: Riccardo has type 1 diabetes, which adds another layer of complexity to his fueling strategy. Read about his T1D fueling strategy.
Validating Lab Results
Using those results as a baseline, I then validate everything in the field during long training sessions and race simulations.
Over time, I observed that at race intensity — especially on the bike — I can sustain very high carbohydrate intake without GI issues, provided the intake is well distributed and based on a glucose + fructose mix aligned with current research.
The 130–140 g/h range is therefore not an arbitrary target, but the upper end of what both lab data and real-world execution show I can effectively use under specific conditions.
Finding Fuel Ceilings and Minimums
I don’t treat 130-140 g/h as a fixed goal, but as a ceiling I approach only when intensity, duration, pacing, temperature, and gut comfort all justify it.
At the other end of the spectrum, I also know the minimum carbohydrate intake that still allows me to perform reliably on race day when conditions do not justify pushing intake higher.
For example: In lower-level local races, colder conditions, or lower overall demands, the lowest intake that consistently works for me is around 100 g/h on the bike and ~60 g/h on the run, allowing me to perform at my baseline level without compromising glucose stability or execution.
Carbohydrate Ratio Matters
I know from repeated testing that I reliably run into GI issues when using mixes with a 2:1 glucose-to-fructose ratio. This isn’t based on trends or theory, but on multiple real-world trials where that ratio consistently caused problems.
By contrast, the 1:0.8 ratio has proven markedly more tolerable and stable for me.
Different Strategies for Bike and Run
In practice, on the bike I can occasionally push intake even higher — up to ~160 g/h in very specific conditions — thanks to lower mechanical stress and better fueling control.
On the run, intake is naturally lower: in optimal conditions I can sustain around 100–110 g/h, but in most cases I deliberately stay closer to ~90 g/h to protect gut function and execution.
Scaling Down during Training
Outside of race contexts, I deliberately scale intake down. During long, very easy rides, I typically aim for around 60 g/h on the bike, while during very easy but long runs I stay in the 30–40 g/h range, focusing on glucose stability, liver glycogen preservation, and recovery rather than maximal fueling.
If the effort is equal or shorter than 1h, I typically avoid any carbs. I sometimes push up to 75' without carbs but exclusively for enabling lipolysis processes (of course, empty stomach 3.5h before the effort).
Riccardo's fueling strategy was built on strategic testing, experimentation, and validation. Not sure what your number is? Start with our Fueling Calculator.