Imagine finishing a ride you know well. The bike is back against the wall. You have rinsed the bottles, opened your training app and found a number that makes you look twice. The score is different from what you expected. Before long, you are wondering whether the ride counted, whether your fitness has slipped or whether tomorrow needs to change.
Pause at the first question. What, exactly, changed?
A training number can be useful. So can the moment when you stop treating it as self-explanatory. Before you build a story around a score, give yourself a chance to understand how that score was produced.
Find the source before choosing the explanation
Start with the name of the metric and the activity it describes. Are you looking at the same ride in two places, or comparing today with another day? Is one number calculated from power and the other from heart rate? Are both using the settings you intended?
TrainingPeaks provides a concrete example. Its documentation explains that, when a workout has the relevant recorded channels, athletes can select power, heart rate or pace as the source for calculating Training Stress Score. The selected value then feeds the weekly summary and other charts. It also warns that changing the calculation source on an older workout uses current threshold settings, which may not represent that earlier point in time. [1]
That is a reason to investigate a surprising comparison before interpreting it. It is not a reason to switch settings until the number looks better.
Keep the original question small
You do not have to audit your entire training history because one score caught your attention. Begin with one activity and one discrepancy.
Write down what you expected, what you actually saw and where you saw it. Keep the original activity available. If something in the setup changed, such as the recording device or a threshold setting, note when it changed rather than trying to reconstruct that detail later.
For example, you might tell your coach: “These two rides look similar to me, but their training scores are quite different. Can we check which data and settings were used before we decide what the difference means?”
That is a useful question. It leaves room for several answers, including the possibility that the rides were more different than they first appeared.
Bring your coach into the interpretation
It is tempting to solve the uncertainty alone, especially when the app puts the controls within reach. But changing a calculation and deciding what to do with the result are separate decisions.
If you work with a coach, show them the discrepancy and the context before revising the plan. Ask what the number can reasonably tell you, what other evidence would help and whether anything needs to change. If you agree that a recording or setting needs correcting, keep a note of the correction and the reason.
The aim is a shared understanding you can use. An athlete should be able to ask why. A coach should be able to see the question, the evidence and any decision that follows.
Choose understanding over a prettier dashboard
There is satisfaction in a clean chart. There is more value in knowing what you can trust about it.
Sometimes a closer look will reveal a recording or calculation issue. Sometimes the number will stand up to scrutiny, and you will have a better question about the training itself. Either outcome is more useful than quietly changing the score or rearranging a week around an unexplained difference.
The next time a metric surprises you, try this: identify the activity, identify the source and write down what changed. Then decide, with your coach when you have one, what the evidence actually supports.
You have already done the work of the session. Give the interpretation a little care too.
Source
[1] TrainingPeaks Help Center, Can I change TSS to Heart Rate, Power, or Pace? Updated December 18, 2025; checked October 23, 2026. https://help.trainingpeaks.com/hc/en-us/articles/115007309027-Can-I-change-TSS-to-Heart-Rate-Power-or-Pace
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