When I run to pace, my heart rate is outside the range specified by TrainAsONE. What should I do?

It is very common for pace and heart rate to diverge, with many runners noticing an actual heart rate that is higher or lower than the range specified. If you feel normal and aren't experiencing unusual fatigue, there is generally no cause for concern.

1. What should I do during my run?

Ultimately, TrainAsONE is designed to support your training preference. You should use the metric — be it pace, heart rate, Running Power, or simply perceived effort — that you feel most comfortable with and that works best for your running environment.

The relationship between pace and heart rate isn’t a fixed line; it is a moving target influenced by sleep, stress, temperature, and terrain. Therefore, many successful users find a "hybrid" approach works best, prioritising the true "intent" of each workout:

• For Slow/Easy/Recovery Runs: Prioritise Heart Rate. If staying within the specified heart rate range means running slower than the target pace, stay in the HR range. This ensures a genuine aerobic effort and proper recovery.
• For Fast/Interval Runs: Prioritise Pace. Heart rate is a "lagging" indicator; during short, intense bursts, your interval might be finished before your heart has had time to rise into the specified range.

2. Why is there a mismatch?

• Natural Variability: On some days, your body simply has to work harder due to external factors like heat, caffeine, or lack of sleep. This doesn't mean the system is "off"; it is reflecting your real-time state.
• The "Noise" Factor: Recording devices are not perfect. Factors like "cadence lock" or poor sensor contact can create "noise." If your heart rate range is naturally narrow, even a small amount of data noise can make the specified target feel "off."
• Statistical Ideals vs. Confidence Ranges: It is important to clarify that the targets for the workouts are the statistical ideal, and the ranges represent the statistical confidence on these. If the system is extremely confident on the pace, the pace range will be narrow. However, if it is less confident on the heart rate, its range will be wide. It therefore follows that the target values will not necessarily equate to each other, nor that the lower pace range value will equate to the lower heart rate range value (and likewise for the upper range values).
• Physiological Modelling: In our Artemis 2 model, the heart rate ranges you see are a consequence of the AI’s understanding of your unique physiology. If they don't match your pace yet, the model is likely still refining its map of your cardiovascular response.
• Narrow Heart Rate Ranges: Some individuals naturally have a very small heart rate "window" even across a wide range of paces. This makes specification extremely difficult for models. Artemis 2 is designed to learn such narrow physiological profiles, but it requires consistent data to pinpoint exactly where thresholds lie. (See Why is my heart rate target the same or nearly the same for different pace steps? for further discussion.)

3. How Artemis 2 Handles Discrepancies

Our next-generation AI engine, Artemis 2, is designed to be "sensor-agnostic." Whether you choose to follow the pace target or the heart rate target, the AI performs a second-by-second analysis of all your data. It recognises when you’ve adjusted your pace to manage your effort and uses that information to continually refine your "physiological fingerprint."

Note: TrainAsONE's Artemis v2 algorithm is now in Open Beta. It removes generic, age-based formulas in favour of machine learning based on your actual data. You can enable it in your Training Settings under the Training Algorithm field.

4. Accelerating the Learning Process

You can help the AI align these metrics faster by using the Run Confirmation widget. If you ran to pace and felt great, but your HR was outside the predicted range, confirming the run effort as "Easy" or "Normal" provides the high-quality feedback the AI needs to tune its physiological model to your reality.

References and Further Reading

• FAQ: Which is best, training to pace or heart rate?

• Artemis 2

• Cooper, C.B. and Storer, T (2001) Exercise Testing and Interpretation, A Practical Approach. Cambridge: Cambridge University Press.

• Bouchard, C. (1982). Exercise and Sport Science Review. New York: Franklin Institute Press. p. 49-83.

• Atwal S, Porter J, MacDonald P. Cardiovascular effects of strenuous exercise in adult recreational hockey: the Hockey Heart Study. CMAJ. 2002 Feb 5;166(3):303-7.