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August 2, 2022

Carbohydrate burn during cycling

The energy used by the human body during cycling is generally taken from multiple sources, most dominantly body fat and carbohydrates. While body fat is the main source of energy at rest and during light exercise, carbohydrates become the main source of energy when exercise intensity increases. In addition, the amount of energy burnt during cycling and the proportion that comes from carbohydrates is very personally determined. So your personal metabolism hugely impacts your carbohydrate burn during cycling and therefore also how your optimal nutrition plan should look like.

Differences in carbohydrate burn rates explained

As you will probably know, the power you push on the bike equals the amount of energy. So, riding at an intense 300 Watt requires three times as much energy as riding at 100 Watt. However, the proportion of the required energy that comes from carbohydrates also increases. At 100 Watt only 15% may come from carbohydrates, with the other 85% being from fats. At 300 Watt easily 70% of the energy comes from carbohydrates. This adds up to an approximate fifteenfold increase in carbohydrate burn.

Now imagine another cyclist, having a VO2Max that is 15% lower. While the person with the lower VO2Max might also be able to push 300 Watt for some time, it will be a much higher relative intensity for him than for the person with the higher VO2Max. And this can mean that the carbohydrate burn is up to 30% higher.

Impact on in-ride carbohydrate intake

Let’s translate the carbohydrate burn into the need for carbohydrate intake during the ride. Say you do an intense ride with an average burn of 120 grams per hour for 4 hours and you can use 300 grams of glycogen before your performance get impaired. This would mean you need to consume 120 x 4 – 300 = 180 gram, which equals 45 grams per hour.

In such cases a 30% increase in your carbohydrate burn to 156 gram/hour, leads to an extra 144 gram burn which you fully need to replenish. This would almost double your in-ride nutrition intake need, otherwise your performance will get impaired. This is a typical example where insufficient nutrition can cause a rider not to reach his optimal potential.

In short, your personal metabolism is key to the nutrition planning of your rides. As a Premium user of EatMyRide you don’t have to worry about this, because it is taken into account when you plan your rides. Also, for every planned or actual ride you will see your glycogen usage. You can see your personal metabolism in the EatMyRide app via ProfilePersonal.

Do you want to know your carbohydrate burn in real time during your cycling ride? With the Carbohydrate Burn/Intake Balancer you can track your burn, intake and glycogen usage on your Garmin Edge device.