Fueling estimate: carbs burned and what to bring

The fueling estimate shows how much carbohydrate and fat a workout burned and how much energy it took. On a planned ride it becomes a fueling plan: how many carbs to bring and how many to eat each hour. You see it on all your athletes' rides and runs; your athletes see it on their own workouts with Premium.

Which workouts get one

• Rides with a power meter, from the power and the athlete's FTP on the day of the ride.
• Runs, from pace, the hills and the athlete's weight, with their threshold pace (or threshold heart rate when there is no threshold pace).
• Planned rides with a power target on every step (watts, % of FTP or power zones). They get a fueling plan.
• Other sports, and rides without power data, don't get one.

After the workout

1. Open a completed ride or run from the athlete's Calendar.
2. On the Summary tab, the Fueling estimate line sums it up: grams of carbs, grams of fat and kcal.
3. Select it to see the breakdown: Carbohydrate burned, Fat burned, Carbs per hour, Energy and Carbohydrate by power zone (by pace zone on runs).

If the ride was planned with power targets, a line under the breakdown shows what was planned, so you can see whether they burned more or less than expected.

Before a planned ride

1. Open a planned ride that has a power target on every step.
2. Under the step bars, Fueling plan reads, for example, Bring about 120 g of carbs · 40 g an hour · 1650 kcal.
3. Select it for Carbs to bring, the carbohydrate and fat the ride should burn, its energy and the split by power zone.

Carbs to bring is about half of the carbohydrate the ride burns, within what the gut can absorb: up to 30 g an hour on rides of 1 to 2 hours, 60 g an hour up to 2½ hours and 90 g an hour beyond. Rides under 75 minutes don't need food on the bike. The plan follows the workout: change a step or the FTP and it updates.

What it needs

• For rides, an FTP in Zones. Without one, the card says Set an FTP in Zones to see the carbohydrate and fat burned on rides.
• For runs, a threshold pace (or threshold heart rate) in Zones, and a weight in the profile or as a metric.
• See Set up training zones.

How it's worked out

Energy comes from the work done: every watt is paid for at a gross efficiency of 22%, typical of trained cyclists, so 1 kJ of work is about 1.09 kcal burned. The share of that energy that comes from carbohydrate rises with intensity, measured against FTP, following an average curve from laboratory studies of trained cyclists who had eaten. On runs the energy comes from pace, gradient and body weight.

It is an estimate. It assumes the athlete ate before training, how much fat each person burns varies, and on very long sessions the carbohydrate share drifts down a little, which it doesn't model. Use it as a guide for planning food, not as a lab measurement.

Turn it off

Select your photo (top right) › My Profile › Nutrition and switch off Show fueling estimates. This hides the estimates only for you; your athletes keep seeing theirs.