Heart-rate zones

What are heart-rate zones?

Each zone comes with a different dominant training effect. The low zones build your aerobic base and support recovery; the middle zones improve your pace endurance; the zones around and above your threshold raise your threshold and maximum oxygen uptake. A good plan spreads training deliberately across those zones instead of doing everything at "moderately hard".

The boundaries between zones are aids, not physiological walls. Training just below or above a boundary isn’t a failure; what matters is the spread across weeks, not putting every minute in the right box.

How do you set heart-rate zones?

Anchor your zones on a measured threshold where possible — your LTHR, threshold pace or FTP — and not on an age formula for maximum heart rate. Formulas like "220 minus your age" can be dozens of beats off for individuals, and all your zones inherit that error.

Set zones per sport: your threshold heart rate in cycling is usually lower than in running, so the same bpm boundaries for both sports rarely fit. Compare zones only within the same sport and against your own history.

Know the limits of heart rate as a steering signal: it reacts slowly to changes in pace (short intervals are better steered by pace or power), and heat, dehydration and fatigue push heart rate up at the same effort. So combine heart rate with pace, power and feel.

How Trimetra personalises this

Trimetra builds heart-rate zones per sport around your own profile anchors: your resting heart rate, your threshold heart rate (separate running and cycling LTHR) and your maximum — so a low resting heart rate honestly counts in where your easy endurance zone starts. The top of that zone additionally learns from your own easy sessions. If your anchors demonstrably shift, the app suggests an update — with the reasoning included — and your zones only move once you accept the suggestion.

Frequently asked questions