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Energy sources

The energy sources breakdown shows how much of different energy sources (fats, carbohydrates, proteins) you used during your session. On your watch, you can see it in the training summary right after finishing your session. More detailed information can be viewed in the Flow mobile app after syncing your data.

During physical activity, your body uses carbohydrates and fat as main sources of energy. The higher your training intensity, the more carbs you use in proportion to fat, and vice versa. The role of protein is usually quite small, but during high intensity activity and during long sessions your body can use about 5 to 10 % of its energy from protein.

We calculate the use of different energy sources based on your heart rate, but we also take your physical settings into account. These include your age, gender, height, weight, maximum heart rate, resting heart rate, VO2max, aerobic threshold and anaerobic threshold. It's important that you've set these settings as precisely as possible so you'll get the most accurate energy source consumption data.

Energy sources summary

After your session, you'll see the following information the training summary:

Carbs, protein and fat you've used during your session.


Note that you shouldn't interpret the used energy sources and their amounts as guidelines when eating after your session.

Detailed analysis in the Flow mobile app

In the Flow app you can also view how much of these sources you used at each point of your session and how they accumulated throughout it. The graph shows how your body makes use of different energy sources at different training intensities, and also at different stages of your training session. You can also compare the breakdown from similar sessions over time, and see how your ability to use fat as the primary energy source develops.

Learn more about energy sources