Carbs on the bike
Carbohydrate recommendations for consumption on the bike are typically up to 60 g per hour if consuming glucose alone, or up to 90 g when using combinations of carbs like glucose and fructose. This is because studies found most athletes, regardless of size, generally oxidized around the same maximum amount of glucose per hour, roughly 60 grams. Size differences appeared minimal or irrelevant.
New study brings weight into the equation
Recently, researchers revisited the issue, proposing that recommendations should consider body weight. Their reasoning seems intuitive. They say that a heavier athlete would use more energy, potentially oxidizing more ingested carbohydrates. In their study, cyclists of varying sizes consumed 90 grams of glucose per hour. And the researchers did find a correlation suggesting heavier cyclists might oxidize more carbohydrates than lighter ones, implying weight-based recommendations might be justified.
Does the data support that?
However, this new study is not that straightforward. Asker Jeukendrup, a renowned sports nutrition scientist, pointed out a few issues when reviewing the data on his blog. These are three of his key observations about the study.
- The correlation relied heavily on a few extreme data points. Riders that seemingly oxidized more carbs than they took in. Removing those outliers made the relationship between weight and carb oxidation disappear.
- The study used glucose alone. We know that combining glucose with fructose significantly increases oxidation rates, possibly altering how body weight affects these results.
- Real-world observations suggest that elite athletes, sometimes even those lighter in weight, often oxidize carbohydrates at the highest rates.
Practical recommendations for cyclists
The real-world implications for cyclists aren’t clear-cut from this new data alone. Not just because of the issues raised above but also because individual responses to carbohydrate intake during exercise vary greatly. They are not just influenced by weight but also by gut tolerance, training history, and habitual diet.
This shows that trying to adhere to any specific formula is unlikely to give the best results for cyclists in real world scenarios. Trying to find a personal optimal carbohydrate intake should always be the goal. The general guidelines mentioned at the start, 60 g to 90 g per hours depending on the source of the carbs, are still an excellent starting point. And then it’s the case of training the gut to be as effective at absorbing carbohydrates as possible. You can read about training the gut in our previous article.
