As an endurance athlete, you burn a combination of fat and carbohydrates as fuel with any exercise you do. The harder you push the pace, the more you rely on carbs as the primary fuel source. The problem is that your stores of carbohydrate fuel — glycogen in your muscles and liver, and glucose in the bloodstream — are limited. This requires that you consume carbs during exercise in order to extend your endurance and delay the onset of fatigue.
It's a proven fact: taking in carbs during endurance training or competitions enables you to perform at a higher intensity for a longer period of time. But the question many athletes ask is, how many carbs to consume?
Conventional wisdom has long held that well-trained triathletes should consume no more than 60 grams of carbs per hour during exercise. This is based on the idea that the maximum rate at which ingested carbs can be absorbed from the digestive tract and metabolized as fuel by working muscles is about 1 gram per minute, or 60 grams over the course of an hour.
However, a new study has toppled the conventional wisdom: it turns out that the 60-grams-of-carbs-per-hour convention was based on research in which only a single carbohydrate source, glucose, was given to athletes. These studies were accurate in showing that glucose alone can't be absorbed any faster than about 60 grams per hour. But in this study, endurance athletes were fed a combination of glucose and fructose in a 2:1 ratio — and instead of topping out at one gram of ingested carbs per minute, the athletes were able to absorb and metabolize up to about 50% more ingested carbs every minute during exercise.
This finding is astounding if you're an Ironman competitor faced with an eight-plus-hour competition, in which carb stores absolutely play an important role in whether you achieve a best time or your performance is undermined — or even ended prematurely — by fatigue. Instead of consuming 60 grams of carbs per hour, you can now consume up to 90 grams of carbs per hour, as long as those carbs are in a 2:1 ratio of glucose to fructose. To make that easy and convenient for you,
PowerBar® Performance Energy bars,
PowerBar® Energy gels,
PowerBar® Energy Blasts gel filled chews,
PowerBar® Energy Bites and
Ironman PERFORM™ sports drinks all feature C2MAX, with the same 2:1 ratio of glucose and fructose that was the subject of this study's groundbreaking research.
How does the unique carb combination work?
The glucose-fructose combination works better than glucose alone, because having multiple carbohydrate sources allows more carbohydrates to be absorbed from the digestive tract. The thinking is that glucose and fructose have their own separate transport systems in the digestive tract, and these transporters help carry ingested glucose and fructose from the digestive tract into cells. However, the glucose transporter can carry only glucose, and, like a train, once it's filled, the train closes and can't carry anymore. But the revelation is that fructose has its own separate transporter, or "train." So, even when the glucose train is filled to capacity, the fructose train can deliver even more fuel to working muscles. Thus, by providing both glucose and fructose, and taking advantage of both transport systems, you can deliver more fuel to your muscles and extend endurance even further.
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This study's research proves the endurance advantage. Trained cyclists were given either plain water, plain water plus glucose, or plain water plus glucose and fructose in a 2:1 ratio. The cyclists rode for two hours and then had to complete a time trial of about one hour's duration. It turned out that when the athletes ingested the combination of glucose and fructose, they achieved a time trial performance that was 8% faster than when they consumed glucose by itself. Plus, average performance time was 19% faster when the carb combination was compared with water alone.
Bottom line: When it comes to fueling endurance workouts and events like an Ironman
®, go with the cutting edge. Make sure to consume a 2:1 ratio of glucose to fructose during exercise, and make sure to consume up to 90 grams per hour of this powerful carb fuel mix. Finally, remember that PowerBar
® C2MAX can give you that cutting edge endurance advantage.
About PowerCoach™
PowerCoach™ is a customizable online training and nutrition tool designed to support both beginners and experienced athletes in meeting their fitness and competitive goals. Created in consultation with PowerBar
® Team Elite
® athletes and coaches, PowerCoach gives athletes the ability to set up nutrition and training plans customized to their fitness level, experience, event, and more. To create your own training and nutrition plan with PowerCoach, go to
www.powerbar.com/powercoach/default.aspx.
References:
Currell K, Jeukendrup AE. Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc. 2008; 40:275–281.
Jentjens RL, Achten J, Jeukendrup AE. High oxidation rates from combined carbohydrates ingested during exercise. Med Sci Sports Exerc. 2004; 36:1551–1556.
Topics:
C2MAX, Energy, Caffeine, Carbohydrates, Endurance, Ironman, Nutrition, Nutrition advice, Performance, PowerBar, PowerBar products, Training, Training advice
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