The complete guide to sports drinks: 2:1 fructose
2:1 Fructose, sports drinks
What are they?
An advanced range of sports drinks, powders, bars and gels containing a blend of carbohydrate in a 2:1 ratio of glucose to fructose with added electrolytes.
Why use them?
Consuming carbohydrate during endurance exercise delays fatigue and boosts performance, but the amount that can actually be delivered to the working muscles is limited by the rate at which it can be absorbed from your digestive tract.
Current recommendations to consume 30-60g of carbohydrate an hour during prolonged exercise are based on research showing that glucose absorption is capped at around one gram per minute (or 60g per hour), with studies showing that higher concentrations are simply not absorbed, and can result in stomach upset.
However, more recent research focusing on the impact of combining different types of carbohydrate has shown that when glucose is consumed with fructose, carbohydrate absorption can exceed 1.5g per minute, increasing the rate of delivery to the muscles to up to 90g per hour. This is thanks to the fact that fructose is transported and absorbed via a different mechanism to glucose.
Put simply, by combining carbohydrates, you can overcome the 60g per hour saturation rule, which increases fuel availability. But does this translate to better performance? Research suggests yes - in a 2004 trial comparing glucose, glucose/fructose or control (water) beverages in trained cyclists; rates of carbohydrate oxidation were 36 per cent higher with the glucose/fructose beverage versus the pure glucose drink.
In addition researchers found that the glucose/fructose drink spared the body's stored carbohydrate, improved water uptake from the gut and reduced the rate of perceived exertion. More recently, researchers at Birmingham University simulating a one-hour time trial after two hours of riding found an eight per cent improvement in performance when using glucose/fructose beverage, compared to a glucose-only drink.
How do I use them effectively?
For rides lasting over an hour, try swapping your usual sports drink or gel for a 2:1 product to increase carbohydrate delivery from 60g to 90g per hour - this equates to 1,500ml of a drink, three gels or three bars.
Remember, any change in your fuelling strategy should be tried and tested, so don't make the switch on the day of a competition - work towards titrating your usage upwards from the standard 60g per hour.
It's worth noting that although absorption is reported to be up to 90g per hour, recent evidence presented by experts from Gatorade suggests that 78g per hour may be the optimum dose for performance benefit.
Are they better than real foods?
Although a relatively new area of sports nutrition, multiple transportable carbohydrates have definite benefits which could translate into that all-important performance edge during an event. The advantage of 2:1 products is convenience and the precise ratio of glucose to fructose for maximise absorption.
Carbohydrate foods do contain a mix of sugars (bananas provide glucose and fructose in a 1:1 ratio), so you could experiment with different sources, although getting 90g of carb in the all-important 2:1 ratio will require some maths. Alternatively try experimenting with a homemade drink using a mix of maltodextrin or glucose and fructose.
A combination of maltodextrin and fructose enables you to absorb more carbohydrate
C2Max is a blend of glucose and fructose with a high level of sodium to prevent cramping.
High5 Energy Source
Maltodextrin and fructose with key electrolytes provides up to 90g of carbohydrate per hour.
The original version of this article was published in the April 4 2013 issue of Cycling Weekly magazine