Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "

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Optimal carb dose for cyclists is 78 g per hour

Cyclists and triathletes perform best during races if they consume 78 g per hour of easily absorbed carbohydrates. Higher doses don't work better but are worse, according to a human study carried out in the US and funded by Gatorade. The results will be published soon in Medicine and Science in Sports and Exercise.

Optimal carb dose for cyclists is 78 g per hour
Sports drinks, gels or bars containing easily absorbed carbohydrates are among the most effective supplements available to endurance athletes like marathon runners, triathletes and cyclists. But the amount of absorbable sugars that the body can absorb is limited. If you consume pure glucose then your body can process about 60 g an hour. If you take glucose mixed with easily absorbed carbohydrates, then the amount is about 90 g per hour.

Studies have shown that the amount of easily absorbed carbohydrates that boosts athletes' performance varies from 22 g/hour to 180 g/hour. Organisations such as the American College of Sports Medicine think that endurance athletes are best off consuming 30-60 g easily absorbed carbohydrates per hour. These researchers wanted to define the optimal dose more precisely.

In their laboratories they got 51 recreational male triathletes and cyclists to cycle four times. The subjects first had to cycle for two hours at a fixed amount of exertion, after which they had to cycle for a distance of 20 km as fast as they could. The subjects cycled for about 160 minutes in total.

During each session the athletes were given one litre of sports drink containing electrolytes every hour. The amount of carbohydrates in the drink varied: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 or 120 g carbs per hour. The researchers used a mixture of glucose, fructose and maltodextrin in equal proportions.

The figures below show that the 80 g carb dose gave the best results.

Optimal carb dose for cyclists is 78 g per hour

Optimal carb dose for cyclists is 78 g per hour

The researchers calculated a dose-effect curve [above] which showed that 9. 19, 31, 48 and 78 g/hour carbohydrate supplementation caused an improvement of 1, 2, 3, 4 and 4.7 percent respectively.

"The ingestion of small amounts of carbohydrates - 10-60 g/hour - can provide some performance benefit", the researchers write. "In most training situations, this level of performance enhancement is likely sufficient. This study also suggests that in competitive race settings the athlete would benefit from a CHO ingestion rate of 78 g/hour. The optimal range is estimated to be 68-88 g/hour."

Med Sci Sports Exerc. 2012 Oct 2. [Epub ahead of print].

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