How does Trait work out my paces – and why do they change over time?

Many of the questions we get are about paces: "too fast", "too slow", "why did this change?". So here's a calm, step-by-step explanation of how your paces come about and how they settle in over time.

Step 1: Your starting point in onboarding

Trait distinguishes two components of fitness: your general endurance (cardiovascular) and your running ability, which is mostly muscular. A well-trained cyclist can have great endurance and still not be able to run a half marathon. That's why Trait asks you two things:

• Your level (from "Just getting started" to "Expert") determines how long and how extensive your sessions are. If you can't yet run 5 km in one go, you won't get a 60-minute session.
• Your feelgood pace is the first reference point for your paces: the speed you'd naturally settle into on an easy, relaxed run. It defines the centre of Zone 1, and all the other zones hang off it. Read more at What is the feelgood pace?

Level and feelgood pace are cross-checked – a feelgood pace of 4:00/km, for example, doesn't fit with "can't yet run 5 km in one go". Contradictions like that are rare; beginners usually have a feelgood pace around 7:30/km.

Important: Right after you start, your paces are deliberately only rough. At this point Trait still knows very little about you. That's not a bug – it's the starting point for calibration.

Step 2: Three mechanisms refine your paces

1. Data import from your watch or service
When you connect a watch or service for the first time, Trait analyses your runs from the last three months. If your typical speed is clearly off from the feelgood pace you entered (say you usually run 6:30 instead of 7:30/km), Trait will suggest faster zones in a dialog. You can accept or decline.

2. The checkout after every workout
After each session you rate your subjective effort from 0 to 10. Trait compares it with the effort that would be expected for that session – for an easy Zone 1 run, roughly 5 to 7.

• Much harder than expected? Trait looks at the data first. If you ran faster than prescribed, that's the explanation. If you ran at the prescribed pace, your paces are probably too fast – Trait suggests lowering them.
• Much easier than expected? If the same session feels a lot easier in month three than in month one, that's a sign your fitness has improved – Trait suggests raising your paces.

This happens after every checkout, not just in the first few weeks. That's why an honest rating matters so much: if you deliberately rate too low or too high out of fear of being "downgraded", you distort the calibration.

3. Heart rate analysis, roughly once a month
Independently of your subjective rating, Trait compares your heart rate in segments of equal pace (for example 1–2 km) with the previous month. If it drops at the same pace – say from 140 to 134 beats – that's an objective sign you've got fitter, and Trait suggests faster paces. For this, Trait needs heart rate data from your watch.

You stay in control

In all three cases Trait makes a suggestion. Whether you apply it is up to you. Everyone can see the analyses; applying the suggested pace adjustment is a Pro feature.

On top of that, there's the assessment run (Pro), which specifically calibrates your fast zones, and the option to shift all paces together faster or slower.

By the way: your paces are usually fixed 14 days in advance. Sessions further in the future deliberately don't have paces yet – they'll only be set based on how you develop until then.

Special case: plan with a fixed goal time

If you chose a fixed goal time during onboarding (for example "Marathon in 4:00 h"), things work differently: all paces are then derived backwards from the goal time and are already set for every week. The dynamic suggestions after checkout and the monthly heart rate analysis are switched off in this mode – after all, you've set yourself the task of hitting that time. If the paces there consistently feel wrong, the goal time usually isn't realistic. In that case, a new plan with an adjusted goal time or switching to individual training will help.

What has no influence

Personal bests don't affect your paces. Trait detects personal bests automatically from your activities; the personal bests list can't currently be edited, and the tip sometimes given in the past – "enter your goal time as a personal best so the paces fit" – is wrong. The "Enter current performance" feature (on the Stats page below the predictions) also only improves your prediction, not your training paces. Your paces come exclusively from your feelgood pace, checkout ratings, heart rate analysis and assessment run.

If the paces still don't fit

The system generally works well. When it doesn't, it's almost always down to consciously or unconsciously inaccurate input: a misjudged feelgood pace, sugar-coated effort ratings, or paces that were manually overridden right from the start. You'll find concrete tips at My paces don't fit me – what can I do?