Heart rate zones for runners: what Zone 2 really means

So here's the plain version: what the heart rate zones are, why Zone 2 gets all the attention, and how to use them without letting your watch run your life.

Zones are just bands of effort, measured by heart rate. Most systems split your range into five, from a walking warm-up at the bottom to an all-out sprint at the top. The exact numbers depend on your own heart, not a chart, which is the part most people skip.

Roughly, the five look like this:

The boundaries matter less than the idea behind them: most of your running should be genuinely easy, and a small amount should be genuinely hard. The trouble starts in the middle.

Zone 2 is where you build the aerobic engine that everything else sits on. More capillaries, better fat-burning, a stronger heart, less fatigue at the same pace. It's slow work, in both senses, but it's the foundation, and it's the part most amateurs cut short because it feels too easy to matter.

The rule of thumb that survives contact with reality: keep the clear majority of your weekly running easy, and let the hard days be properly hard. If your easy runs are a bit quick and your hard runs are a bit soft, you end up spending your whole week in Zone 3, tired but not improving. Coaches have a name for that grey zone, and none of them mean it as a compliment.

Running easy too hard. It's the single most common error I see, and it's completely understandable, because Zone 2 pace often feels insultingly slow at first. You want to push. You feel fine. Then Thursday's session is flat and you can't work out why.

If you have to walk the hills to stay in Zone 2, walk them. It stops feeling slow within a few weeks as your aerobic fitness catches up, and your hard days get better because you actually recovered from the easy ones.

The 220-minus-age formula for maximum heart rate is a rough starting point and nothing more — plenty of runners are 15 beats either side of it. If you want something closer to reality, a simple threshold test (a hard, steady 20 to 30 minutes and the average heart rate from it) gives you a personal anchor to set the zones from.

But don't turn it into a science project. The point of zones is to keep your easy days easy and your hard days honest. Where the hard end is concerned — intervals, tempo, and speed work — the zone is a guardrail, not the goal. If you want the structured version of that fast running, that's what our speed and interval training is built around.

Zones only help if you actually use them, run to run, and that's the annoying part — it means watching your heart rate mid-session and adjusting. TrainPlan reads the heart rate your watch already records, sets your paces from your recent running rather than a generic table, and adapts the plan when the data says you need it. If your ”easy” runs keep drifting hard, that shows up, and the plan responds instead of quietly digging you into a hole. It adapts week to week and tells you why it changed.

You don't need an app to train by heart rate. But if you'd rather not do the zone maths on every run, that's the idea.