Welcome to a new series of sports nutrition articles sponsored by High5 in which their product development scientists explain the way in which today's high tech nutrition products work. This month's feature looks at the science behind 2:1 fructose drinks.
Your sports nutrition should provide:
This the fuel that lets you race both fast and far. 70% of the effort required for a 2:45 to 3:45 marathon is fuelled by carbohydrate and not fat. Unfortunately, your body can only store a limited amount of carbohydrate - typically 400g for a 75kg athlete when rested. Race anything over 90 minutes and your carbohydrate store can be depleted.
Any carbohydrate that you are able to consume during a race (drinks, gels etc) add to your body's store of carbohydrate. High5's new generation of sport drinks with a 2:1 fructose ratio can provide your working muscles with up to 90 grams of carbohydrate per hour. That's 50% more than the best traditional (1) sport drinks can provide.
For optimum performance, you should aim to replace sweat loss by consuming sports drinks. Racing in the heat, it's hard to drink enough to keep up with sweat loss. In hot conditions, you can sweat more than 1.5 litres per hour, the equivalent of two large drink bottles.
The 2:1 fructose formulation found High5 drinks has been shown to deliver fluids faster than traditional sport drink formulations. High5 drinks also contain a relatively high level of key electrolytes.
In moderate doses caffeine can substantially increase the absorption of carbohydrate and fluids. Caffeine also stimulates the body's nervous system, reducing fatigue and making you more alert, increasing your concentration and reducing the feeling of effort during sport. In the right amount (13mg to 6mg caffeine per kilogram of body weight), caffeine is an effective performance enhancer. A moderate dose of caffeine has not been shown to significantly increase dehydration during sport.
Figure 1 shows caffeine blood plasma levels over time. If you are sensitive to caffeine and experience symptoms such as hand tremors, heart palpitations, etc, then stop using it immediately. If you have a heart condition do not use caffeine. You can continue to follow these guidelines by switching from products containing caffeine, to the equivalent products with no caffeine.
The different types of carbohydrates used in traditional sport drink formulations are first broken down to glucose by your digestive process. That glucose then passes through the wall of your intestine into your blood stream. To pass through the wall of your intestine, the glucose molecules use 'revolving doors' known as the glucose transporters.
As these revolving doors only allow glucose to pass slowly, they limit the amount of carbohydrate your body is able to absorb to 60 grams per hour. For many years, that was thought to be the upper limit to the amount of carbohydrate you could absorb - but not any more.
High5 drinks with their new 2:1 fructose formulation can now deliver up 90 grams of carbohydrate per hour. Fructose (fruit sugar) is a unique carbohydrate, which is not broken down to glucose by digestion. It passes through the wall of the intestine using a different set of doors to glucose.
High5 new drinks contain two parts maltodextrin (a traditional type of carbohydrate that breaks down glucose during digestion) and one part fructose. You can see from the diagram that 90 grams of this 2:1 combination can be absorbed per hour. As carbohydrate is the fuel for speed and endurance, the more you have available the faster and further you can ride.
Most traditional sport drinks and gel contain no fructose or relatively low levels. High5 drinks contain around 33% or more fructose. (2)
Note that the 2:1 fructose formulation simply allows you to absorb more carbohydrate than was previously possible. To benefit from it you must eat and drink more than you would normally.
To find out how to fuel your next triathlon race follow these guides.
(1) A drink formulated with glucose, dextrose, maltodextrine or any other carbohydrate that breaks down to glucose during digestion and before absorption into the blood stream and a drink that contains little or no fructose.
(2) High5 Drinks containing approximately 33% or more fructose are: EnergySource4:1, EnergySource X'treme and Isotonic.