Heart Rate Zones — What They Are and How to Set Them

The five zones

Most coaches use a five-zone model, and the anchor you build it on matters more than the exact lines. Runsense — like most serious coaching — sets the zones off your lactate-threshold heart rate (LTHR) rather than your maximum, because LTHR reflects your physiology instead of a formula. These percentages run higher than the max-HR version of the same zones you may have seen because they're measured against a lower anchor — your threshold sits around 90% of your max, so the scale compresses near the top. The exact boundaries are individual, but the shape is standard:

• Zone 1 (below ~85% of LTHR): recovery — walking, very easy jogging.
• Zone 2 (~85–90% of LTHR): easy aerobic, conversational — the bulk of your training, building the aerobic base.
• Zone 3 (~90–95% of LTHR): moderate, "comfortably hard" — roughly marathon effort.
• Zone 4 (~95–100% of LTHR): threshold — half-marathon to tempo effort, sustainable ~20–40 min when fit; your LTHR sits at the top of it.
• Zone 5 (~100% of LTHR and above): VO₂max and above — short, hard intervals.

How to set your zones

Anchor your zones to your lactate-threshold heart rate (LTHR) — the heart rate at the hardest effort you can hold *steadily* for about an hour. It ties the zones to your physiology, which is why Runsense uses it. The classic do-it-yourself estimate is a hard ~30-minute time trial, but you don't have to run the math: Runsense can prescribe a guided lactate-threshold test and read your LTHR straight from the effort (see testing your LTHR), then build your zones on it.

Setting zones off an age-estimated max instead is the weaker path: the "220 minus age" formula is only a rough population average — yours can be off by 10–20 beats, which throws every zone off. A true max from a maximal effort works, but threshold is the more useful anchor for the tempo and threshold work zones are most often used to guide. However you set them, treat the numbers as a starting calibration and refine them against how efforts actually feel.

Where most of your running lives

The big-picture rule outranks the precise boundaries: roughly 80% of your running should sit in the easy zones (1–2), with hard work a smaller, deliberate dose¹. The most common error is letting easy runs drift up into zone 3 — the "gray zone" — which costs you on the hard days without the aerobic payoff of true easy running.

A caution on trusting the number

Heart rate lags at the start of a run, drifts upward as you tire, and rises with heat, dehydration, caffeine, altitude, and stress — so the same zone can mean different paces on different days. Use zones as one lens alongside pace and perceived effort, not as a verdict. When the number and how you feel disagree, ask why before obeying the watch.