How to Choose Carbohydrates for Your Next Bike Race
Updated: Apr 16
Race Winning Fuel - The Importance of Choosing the Right Carbohydrates
While fitness is undoubtedly a critical factor in your performance, incorporating multiple types of carbohydrates into your race-day nutrition strategy will put you in the best possible scenario to succeed.
The science is clear that consuming carbohydrates during moderate-intensity cycling over 90 minutes in duration improves performance. This includes maintaining cadence in cycling and reduced perceived exertion.
Carbohydrates are made from sugars. For the purpose of this blog I will focus on two sugars; glucose and fructose (although there are many more!).
When consuming carbohydrates during prolonged moderate-intensity cycling or running, research has shown that when we consume glucose alone, we can absorb 1g of carbohydrate per minute across the intestinal wall to get into our bloodstream. This equals 60 grams per hour.
60g of carbohydrates is approximately two gels, two medium bananas, or two sports drink bottles with 30g per bottle.
The limitation of glucose absorption above 1g per minute is proposed to be due to the saturation of the transporters that bring glucose into the intestine. Transporters!? Yes, let me elaborate. Imagine blue doors reserved on your intestinal wall only for glucose entry (called sodium-glucose cotransporter 1 or SGLT1). Now imagine, for visualization's sake, that there are six doors. Each blue door can take 10g of glucose into it.
If you eat 60 grams of glucose in one hour, and your doors for glucose are all full. Nothing else can fit through them. You've saturated the receptors. (This is only an example to help you create a visual, there are many transporters on the intestinal membrane)
Now, What Do I Do? I've Reached My Glucose Limit.
Fructose uses different 'doors' (a fructose transporter protein called glucose luminal transporter five or GLUT5) for absorption across the intestine.
Imagine some additional orange doors only for fructose entry. Now with this additional fructose, you can absorb above 60g of carbohydrates per hour.
In a long hard race over 90 minutes in duration, where you plan to consume above 60g of carbohydrates per hour to keep up with energy needs, using a combination of carbohydrates becomes essential.
By combining glucose and fructose, you can increase your carbohydrate availability. Now you could absorb up to 1.75g per minute or 105g of carbohydrates per hour if needed.
The research suggests this is because you are using two different transporters, one for glucose (SGLT-1) and one for fructose (GLUT-5). When you hear 'multiple transportable carbohydrates,' this is what that term is referring to.
Although I used glucose and fructose in this example, you can combine other carbohydrates to attain absorption above the 1g/minute or 60g/hour we see with glucose alone.
You can learn more about other combinations studied, including maltodextrin+fructose or glucose+fructose+sucrose HERE.
If you're consuming a variety of sports drinks, gels, bananas, bread with jelly, rice bars, etc., you'll be getting a variety of carbohydrates in your sports nutrition.