How does Trait come up with my paces – and why do they change over time?

A lot of the questions we get are about paces: "too fast", "too slow", "why did that change?". So here's a calm, thorough explanation of how your paces come about and how they settle in over time.

Step 1: Your starting point in onboarding

Trait distinguishes between 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 two things:

• Your level (from "Just getting started" to "Expert") determines how long and extensive your sessions are. If you can't run 5 km in one go yet, you won't get a 60-minute session.
• Your Feelgood Pace is the first reference point for your paces: the speed you'd just head out and run at comfortably. It defines the centre of Zone 1, and all other zones hang off it. More on this under What is the Feelgood Pace?

Level and Feelgood Pace are checked against each other – a Feelgood Pace of 4:00/km, for example, doesn't fit with "can't run 5 km in one go yet". Contradictions like this are rare; beginners usually have a Feelgood Pace around 7:30/km.

Important: 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 suggests faster zones in a dialog. You can accept or decline.

2. The Checkout after every workout
After every 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 session, 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 of improved fitness – 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 bpm – 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 the driver's seat

In all three cases, Trait makes a suggestion. Whether you accept it is up to you. Every user 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 the fast zones, and the option to shift all paces together faster or slower.

Special case: plan with a fixed target time

If you chose a fixed target time in onboarding (for example "Marathon in 4:00 h"), things work differently: all paces are then derived backwards from the target 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 given yourself the job of hitting that time. If the paces consistently feel wrong there, the target time is usually not realistic. In that case, a new plan with an adjusted target time or switching to individual training will help.

What has no influence

Personal bests don't affect your paces. The tip sometimes given in the past – "enter your target time as a personal best" – is wrong. Entering personal bests is only there to correct incorrectly detected PBs.

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 wrong input: a misjudged Feelgood Pace, flattering effort ratings, or paces that were manually overridden from the start. You'll find concrete tips under My paces don't fit me – what can I do?