Zone 2 running: how slow, how much and how to find it

What is zone 2 running?

Zone 2 is easy aerobic running just below your first threshold: the point where breathing starts to deepen and blood lactate begins to rise above resting levels. You can hold a conversation. The catch is that the name means different things in different zone models, so check which one a plan or a watch is using.

In the research model, zone 2 is the zone to limit. In the coaching model, zone 2 is the zone to fill. Both describe the same advice: do most of your running clearly below the first threshold. When this guide says zone 2, it means the easy aerobic running of the coaching model.

How do I find my zone 2?

Start with the talk test: run at the fastest pace where you can still speak in full sentences without gasping, then note your heart rate at that pace. In a 2022 review, the talk test and an effort rating of 10 to 11 on the 6 to 20 scale matched the first ventilatory threshold. Formulas and watch zones are only starting points.

Our recommendation: run 20 minutes at a talk-test pace on flat ground and note the heart rate over the last 10 minutes. That reading, plus 5 beats, is your ceiling for easy runs. Re-check it every 6 to 8 weeks, because fitness, heat and tiredness move it.

How slow does zone 2 running feel?

Slower than most athletes expect, often more than a minute per kilometre slower than 10 km race pace (our estimate). It should feel easy, with relaxed breathing, and you finish feeling you could run longer. Pace is a poor guide on hills or in heat, so let breathing and heart rate set the limit.

• These ranges are our estimate. Individual spread is large, and the talk test and heart rate overrule the table.
• On hills, slow down or walk so that your breathing stays easy. Pace will fall; that is normal.
• In heat, your heart rate climbs at the same pace. Drop the pace and judge by effort, not by the old number.
• A good sign is that, over several weeks, the same heart rate gives you a slightly faster pace (our reading, not a tested rule).

How much of my weekly running should be zone 2?

About four fifths of your running time, and roughly three quarters of your kilometres, because easy runs are slower. Descriptive studies of strong endurance athletes find about 80 percent of sessions at low intensity and 20 percent at high intensity. This split is our recommendation, not a rule.

Results are mixed. A 9-week trial of 48 runners, cyclists, triathletes and skiers found the polarised group raised peak oxygen uptake most, by 11.7 percent. A larger analysis found no difference between polarised and pyramidal plans. The firm message is to keep most volume easy, which fits the how much running guide.

How many kilometres of zone 2 running a week is that?

Take about three quarters of your weekly running distance. For a recreational runner on 20 to 30 km a week, that is 15 to 23 km of easy running, usually two easy runs and the long run, with one quality run on top. The table uses the weekly levels of the running guide and is our estimate.

Count only the running. If you swim or ride easily on other days, that adds aerobic volume without the impact. Raise the volume by no more than about 10 percent a week, as set out in the weekly training structure guide, and keep one week in four lighter.

Is zone 2 enough for a fitness race or a triathlon?

No. Zone 2 builds the aerobic base, but the race asks for more. Add one quality session a week, race-specific work and strength. For a fitness race that means compromised runs and stations. For a triathlon it means threshold work and bricks. No study has tested zone 2 on fitness racers, so this is our recommendation.

Set zones for each sport. Your heart rate on the bike and in the water is usually lower than when running, and the long-distance triathlete study used separate zones for each discipline. The triathlon training hours guide covers the weekly time, the half-distance triathlon plan puts it in a schedule, and strength for endurance athletes covers lifting alongside it.

What are the common zone 2 mistakes?

The biggest mistake is running easy days too fast, which lands in the moderate zone: hard enough to tire you, not hard enough to be a quality session. The second is turning every run into zone 2. Both are about keeping the easy runs easy and the hard runs hard.

1. Running easy days at a pace that needs short breaths. Slow down until you can talk.
2. Trusting a formula over your body. The 10.8 beat standard error is larger than the zone.
3. Ignoring heat, sleep and caffeine, which raise heart rate at the same pace.
4. Doing only zone 2. Keep one quality session a week, such as intervals or a compromised run.
5. Adding volume and speed in the same week. Change one thing at a time.

Can Tuffr help me plan easy running?

Tuffr is an iPhone app for athletes who train for fitness races and triathlon. It is not public yet: the closed beta is due by 30 November 2026, and a small group goes first. We are building it to keep your easy running in one plan.

• One plan for running, stations, cycling, swimming and the gym, so easy volume on the bike sits next to your runs.
• Coach AI, which proposes changes. You see what would change and why, and only what you approve reaches your calendar.