Zone 2 running, explained.

Zone 2 running is easy, conversational running: slow enough that you could chat the whole way, steady enough that it still counts as training. It’s the bulk of what endurance athletes do, and it’s also the part most runners get wrong, usually by running it too fast.

Here’s what “zone 2” actually means (it isn’t the same everywhere), how to find your own range, and how much of your week it should take.

What zone 2 running actually is

Heart-rate zones slice your effort into bands, from very easy to all-out. There are three common ways to draw the lines:

• Percentage of maximum heart rate. Zone 2 is usually 60–70% of your max. Simple, but it ignores your resting heart rate.
• Percentage of heart-rate reserve (the Karvonen method). Reserve is max minus resting heart rate; each zone is a slice of it, added on top of your resting heart rate.
• Physiological thresholds measured in a lab: the first and second ventilatory (or lactate) thresholds.

Here is the catch. In sports science, training is often split into three zones around those thresholds: zone 1 is everything below the first threshold, zone 2 is the band between the two thresholds, and zone 3 is above the second (Seiler, 2010). In the five-zone heart-rate models used by watches and apps, zone 2 is the second-easiest band and sits below the first threshold.

So the “zone 2” on your watch roughly matches “zone 1” in the polarized-training research: “avoid zone 2” and “run mostly in zone 2” can both be right. Devices also have their own defaults: Apple Watch, for example, calculates zones from your health data and lets you edit them by hand (Apple).

Zone 2 heart rate: a worked example

Take a runner with a maximum heart rate of 190 bpm and a resting heart rate of 55 bpm. Their heart-rate reserve is 190 − 55 = 135 beats. With zone bounds at 50, 60, 70, 80 and 90%:

The same body gets two zone 2 ranges, about 20 beats apart. Both are estimates built on numbers you may not know precisely, which is why the talk test below is a useful tiebreaker.

Where your max heart rate comes from

“220 minus your age” is the classic shortcut, but it is a population estimate, not a measurement. A large meta-analysis proposed 208 − 0.7 × age instead and found that the old formula underestimates max heart rate in older adults (Tanaka et al., 2001). Either way, individuals sit well above or below any age formula. If you have seen a higher number at the end of an all-out race, that number is a better guide. Your resting heart rate is easiest to read first thing in the morning, or from your watch’s trend in Apple Health.

How to find zone 2 without a lab: the talk test

The talk test is exactly what it sounds like. While running, say a couple of full sentences out loud (in studies, people recite a short standard passage) and notice how it feels:

• Comfortable: you can speak in full sentences without gasping. In research, this “last positive” stage produced intensities suited to long, easy sessions (Woltmann et al., 2015). This is your zone 2.
• Possible, but not quite comfortable: this “equivocal” stage sits around the first ventilatory threshold, the top of easy running (Bok et al., 2022).
• Not possible: you’re well into the hard zones.

Use it to calibrate the numbers: run 10–15 minutes at a pace where talking is comfortable, then compare your heart rate with your watch’s zone 2. If the watch says zone 3 while you could chat for an hour, your zones may be set too low.

Why easy running works

When researchers tracked well-trained junior cross-country skiers for 32 days, about 75% of their endurance sessions were below the first threshold and 15–20% above the second, with surprisingly little time in between (Seiler & Kjerland, 2006). Across many studies of national and international-level endurance athletes, the pattern converges on roughly 80% of sessions at low intensity and about 20% dominated by hard work (Seiler, 2010).

Does it hold for ordinary runners? In a 10-week study of recreational runners, a polarized group (about 77% easy, 3% moderate, 20% hard) and a group doing much more moderate running (about 46/35/19) both improved their 10K, by 5.0% and 3.6%. The overall difference wasn’t statistically significant, but the runners who stuck closest to the polarized pattern improved more (Muñoz et al., 2014). The honest summary: lots of easy running plus a little hard running is a sound default, not magic.

Why zone 2 pace feels so slow

If you’re new to heart-rate training, zone 2 pace can feel embarrassingly slow. Three common reasons:

• Hills. Heart rate climbs fast on any incline. Shorten your stride, or walk the steep parts: walking to stay in zone is a perfectly good tool, not a failure.
• Cardiac drift. On a long run at a steady pace, heart rate slowly rises while the heart pumps a little less blood per beat (Coyle & González-Alonso, 2001). Dehydration and a rising body temperature make the drift larger (Coyle, 1998). On hot days and late in long runs, let your heart rate set the pace and slow down.
• A young aerobic base. Over weeks of consistent easy running, the pace you can hold at the same heart rate usually creeps down. That “pace at equal effort” is a better progress signal than any single fast run.

Zone 2 or zone 3?

Zone 3 is the “comfortably uncomfortable” band: talking gets choppy and it feels productive, which is why it creeps into easy days. The trouble isn’t zone 3 itself; it’s every run becoming the same medium effort, so easy days aren’t easy enough to recover and hard days aren’t hard enough to count.

Use zone 3 on purpose: a tempo or threshold session, the last few kilometers of a progression run, or race-pace practice for a half marathon. On easy days, if your watch keeps showing zone 3, slow down until talking is comfortable again.

How much zone 2 per week

A practical starting point is the 80/20 pattern above: around four easy sessions for every hard one. For a runner doing four runs a week, that might look like this:

Even the interval day is mostly easy jogging. If you’re just starting out, keep every run easy for the first weeks, then add one harder session: see how to structure interval sessions.

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