Training
What is Zone 2 training?
The easy, conversational effort that builds your aerobic engine: why it matters, how to find yours, and where it sits in the five zones.
Zone 2 training is easy, sustainable aerobic exercise at roughly 60 to 70 percent of your maximum heart rate, the intensity where you can still hold a full conversation. It is the effort that builds your aerobic base, the foundation every faster session is stacked on top of.
Heart-rate zones split your effort into five bands, from very easy recovery up to all-out. Zone 2 is the second band: comfortably easy, but not a stroll. It should feel like you are working, yet you could keep going for a long time.
Why Zone 2 matters
Easy aerobic training drives the adaptations that make you a better endurance athlete: more capillaries feeding your muscles, more mitochondria to produce energy, a stronger heart that pumps more blood per beat, and a better ability to burn fat for fuel. Crucially, it delivers this at a low enough stress that you can do a lot of it without breaking down, which is why the best athletes spend most of their week here.
The common mistake is running easy days too hard. That leaves you perpetually a little tired, so your hard days are not hard enough either. Keeping easy sessions genuinely easy, in Zone 2, is what lets your hard sessions be truly hard.
The five heart-rate zones
| Zone | % of max HR | Feel | Purpose |
|---|---|---|---|
| Zone 1 | 50–60% | Very easy | Recovery, warm-up |
| Zone 2 | 60–70% | Conversational | Aerobic base |
| Zone 3 | 70–80% | Moderate | Tempo, aerobic power |
| Zone 4 | 80–90% | Hard | Threshold |
| Zone 5 | 90–100% | Maximal | VO2 max, speed |
Percentages use the common max-HR method. Zones based on lactate threshold or heart-rate reserve shift the exact numbers slightly, but the idea is the same.
How to find your Zone 2
Start with the talk test: if you can speak in full sentences, you are likely in Zone 2; if you are reaching for breath between words, ease off. For exact numbers, work out your five zones with the heart rate zone calculator and keep your easy runs inside the 60–70% band. To pair effort with pace, the pace calculator helps you see what those easy efforts translate to on the road.
Frequently asked
What is Zone 2 training in simple terms?
Zone 2 is easy, sustainable aerobic exercise at roughly 60 to 70 percent of your maximum heart rate. It is the effort where you could hold a full conversation. It builds your aerobic base, the foundation that makes every other type of training work better.
How do I know if I am in Zone 2?
Use the talk test: in Zone 2 you can speak in full sentences without gasping. If you can only manage a few words, you have drifted too high. For a number, work out your five heart-rate zones from your max HR and keep your easy sessions inside the 60 to 70 percent band.
How much of my training should be Zone 2?
For most endurance athletes, roughly 70 to 80 percent of weekly training time should be easy Zone 1 to Zone 2 work, with the remaining 20 to 30 percent at harder threshold and interval efforts. This 'polarised' balance is what lets you train more without breaking down.
Why does Zone 2 feel too slow?
Because it is meant to. Most runners habitually train too hard on easy days and too easy on hard days, which leaves them tired but not fitter. Zone 2 feels slow at first, but as your aerobic engine grows you will cover the same effort at a faster pace.
Can I do Zone 2 on the bike or in the pool?
Yes. Zone 2 is an effort level, not a sport. Cycling and swimming at a conversational, sustainable intensity build the same aerobic base as easy running, which is why triathletes rely on it across all three disciplines.
Base first, speed later
Zone 2 builds the engine. A plan builds the whole athlete.
Gritup balances your week automatically, enough easy Zone 2 volume to grow your aerobic base, with the right dose of harder work layered on top.