It’s well known to cyclists that carbohydrates are essential for peak performance. For years, 90 grams of carbohydrate per hour has been the highest fueling recommendation (5). Recently, elite-level athletes have been pushing beyond 90g/hr (2).
Now that high levels of carbohydrate fueling have become standard, it would only make sense to continue pushing that ceiling higher if performance continues to rise. Modern-day nutrition products provide carbohydrate absorption with little risk of G.I. distress, allowing for high-level fueling. That raises the question: Are there further performance gains with increasing carbohydrates beyond 90 grams an hour?
Current Recommendations
The nutrition literature widely promotes a scaled approach to carbohydrate intake (4). Scaling is based on ride duration and intensity; as ride duration and/or intensity increase, so should carbohydrate intake. At the high end of the scale, 90g/hr is the upper limit.
This graphic is directly from our carbohydrate fueling guide and illustrates the scaled approach to fueling.
Here’s a scaled approach to carbohydrate intake stretched over a timeline of possible ride durations [1].
Estimates listed are for hourly carb intakes beginning at the start of your ride and assume a high intensity of effort.
Example: If your ride is three hours, shoot for about 75 g/hr of carbs in the first, second, and third hours of your ride.
New Research
A study was recently published in 2022, aiming to investigate whether carbohydrate ingestion at 120g/hr was possible. Cyclists rode a stationary bike for 3 hours at a power target relative to each cyclist, ranging from 235-295w.
Participants were selected with power profiles similar to those of elite-level cyclists. During testing, participants were fed either 90g or 120g an hour (3). Before we discuss the findings, here are a few keywords that may be helpful to define.
- Oxidation Rate: The rate at which carbohydrate is broken down to be used for energy
- Exogenous: Outside of the body—When carbohydrates are consumed during exercise, they prevent a drop in blood glucose while increasing the total oxidation rate of carbohydrates (5).
- Endogenous: Inside the body—The body stores carbohydrates as glycogen. Glycogen is stored in the muscles and the liver. Within the muscles, glycogen serves as the muscle’s immediate energy source. In the liver, glycogen is used to maintain a consistent blood glucose level (5).
Looking at these graphs, the X axis contains time, and the Y axis contains oxidation rates.
Glycogen stores will last for roughly 90 minutes of exercise (2). However, as the rate of exogenous carbohydrates increases, the utilization of endogenous sources decreases. When consuming high rates of carbohydrates, blood glucose is maintained, allowing glucose found in plasma to be utilized as an energy source (5).
The key takeaway here is found in chart (c). As carbohydrate intake increased, so did exogenous carbohydrate oxidation rates (3). Essentially meaning that elite-level cyclists can tolerate 120g/hr. However, toleration of carbohydrate was the only conclusion drawn from this study. Within this study there is no evidence to suggest that 120g/hr provided a greater performance benefit than 90 g/hr.
Circling Back
Although this study provides evidence that 120g/hr is tolerable, such a high rate isn’t always practical. Athletes achieved such high rates during extensive testing within controllable environments.
For some athletes, attempting to aim above 90g/hr can be difficult in practice and cause gastrointestinal problems if not adequately gut-trained (4). Athletes have practiced higher intakes, but they remain untested in the literature.
There is not much evidence to support increased performance from higher fueling protocols, meaning if you’re targeting over 90g/hr, you should test in your training as your results may vary.
What I’ve Found
This year, I’ve experimented with different products and fueling levels, from 90 to 120 g/hr. On a personal note, I have yet to notice a difference between 90 and 120g/hr.
After months of racing, I settled on 100g/hr, primarily due to the convenience of the product I use. Carbs Fuel offers a drink mix with 25g of carbohydrates and gels with 50g of carbohydrates.
I use two scoops in one bottle and one gel per hour for racing, getting me to 100g/hr. A high-density gel allows me to run a moderate concentration in my bottles. These products have a low flavor profile, almost eliminating flavor fatigue.
In Summary
- Scientific literature suggests a scaled approach to carbohydrates, with 90g/hr being the upper limit.
- Elite athletes have been seen pushing above 90g/hr.
- Current research indicates 120g/hr is tolerable; however, no performance benefit has been demonstrated.
- After some experimentation, I settled on 100g/hr due to the convenience of the product I use, as well as testing various g/hr during training and racing.
Final recommendation: Consuming higher levels of carbohydrates is possible, as research has shown the body can handle upwards of 120g/hr. This information opens the door to experimenting with different fueling strategies. Utilize training as an opportunity to experiment and see if higher fueling rates positiveily affect how you feel on the bike.
References
- Cotton, J. (2024, July 19). 130 grams per hour: Inside the wild carbohydrate strategy of a tour de france stage-winner. Velo. https://velo.outsideonline.com/road/road-racing/tour-de-france/130-grams-per-hour-inside-the-wild-carbohydrate-strategy-of-a-tour-de-france-stage-winner/
- Liver glycogen metabolism during and after prolonged endurance-type exercise Javier T. Gonzalez, Cas J. Fuchs, James A. Betts, and Luc J. C. van LoonAmerican Journal of Physiology-Endocrinology and Metabolism 2016 311:3, E543-E553 https://journals.physiology.org/doi/abs/10.1152/ajpendo.00232.2016
- Podlogar, T., Bokal, Š., Cirnski, S., & Wallis, G. A. (2022). Increased exogenous but unaltered endogenous carbohydrate oxidation with combined fructose-maltodextrin ingested at 120 g h-1 versus 90 g h-1 at different ratios. European journal of applied physiology, 122(11), 2393–2401. https://doi.org/10.1007/s00421-022-05019-w
- Jeukendrup, A.E. and M. Gleeson, Sport nutrition. 2024.
- Burke, L.M., et al., Carbohydrates for training and competition. Journal of Sports Sciences, 2011. 29: p. 17-27.