Substrate Utilization (Fat and Carb Calories)

Estimated Fat and Carbohydrate Calories burned fields can be added to the workout Quick View for power-based cycling workouts. 

What Are Fat and Carbohydrate Calories?

Fats and Carbohydrates are two of the primary macronutrients the body uses as energy sources during exercise. 

• Carbohydrates (Glycogen): Stored in muscles and the liver, glycogen is the body's quick energy source, which it increasingly draws upon as exercise intensity increases. Glycogen stores are limited and (for most people) can’t be fully replaced while exercising, which contributes to fatigue and a drop in sustainable exercise intensity.
• Fats: Fat is a more abundant energy source than carbohydrates in the body but takes longer to convert into energy than carbohydrates. The body burns more fat when exercise intensity is low. Training the body to burn fat efficiently saves glycogen stores for high-intensity efforts. 

By training the body to use both energy sources effectively, endurance and overall performance improve.

How Are Fat and Carbohydrate Calories Estimated?

TrainingPeaks estimates fat and carbohydrate calories based on:

• Average power - As recorded by an athlete's device from their power meter.
• Weight - The athlete's last entered weight. 
• Gender - The gender chosen when the TrainingPeaks athlete account was created (Male/female) affects estimation.
• Athlete Category (see below).

Using that information, TrainingPeaks estimates fat and carbohydrate calories burned on the ride using an algorithm created in collaboration with Dr. Iñigo San Millán.

How to Add Fat and Carb Fields

1. Log in to your TrainingPeaks Coach (or athlete account).
2. Click your name.
3. Click settings.
4. Click Layout.
5. Scroll down to 'Workout' and select 'Bike.'
6. 'Available' and 'In Use' Fields will appear. 
7. Drag Fat Calories and Carb Calories from 'Available' to 'In Use.'
8. Open a power-based cycling workout. 
9. In the quick view, you will see calculated Fat and Carb Calories. 

Please note:

• Fat and Carb fields do not appear in the Quick View card by default.
• Adding the Fat and Carb fields into the Quick View changes what you (the coach) see, not what your athlete sees. If you want them to see those fields in their Quick View, you must enable them in their athlete settings.
• If either of these fields (Fat or Carb) is enabled, the value in Calories (i.e., the total calories for the ride) will be the summation of fat kcal + carb kcal, as opposed to whatever the head unit reports back. If the fields are removed from available, the Calories field will revert back to what the device reports.
• Also works for activity type 'Mountain Bike.'

Choosing a Metabolic Profile

The Nutrition section within an athlete's setting houses the athlete's Metabolic Profile, which is a major variable in estimating Fat and Carb Calories. To access it:

1. Log in.
2. Click your name.
3. Click settings.
4. On the left-hand side of the pop-up window, choose 'Nutrition.'
5. Choose the Metabolic Profile that most closely aligns with your athlete.

• World Class- Professionals competing at the highest level (e.g. Olympics, Tour De France, etc).
• Elite - National level elite and professional athletes competing at a very high competitive level.
• Competitive - Age group competitive athletes who participate in competitive events with a focus on performance.
• Enthusiast - Athletes who are relatively new to training or participate in events with the primary focus of completing events.