Training zones explained: Z1 to Z6 by FTP
If you train by watts, you divide your power into zones. Every zone has its own goal and feels different. If you know them, you know why one session should be easy and the next may hurt.
- The zones are percentages of your FTP, not fixed watt numbers.
- Most of the training belongs in Z1 and Z2, only a small part in Z4 to Z6.
- The sweet spot lies at the top of Z3 and the bottom of Z4.
The six zones at a glance
The division goes back to the widespread model by Andrew Coggan. You find it in many apps, including Zombike.
| Zone | % of FTP | Feel |
|---|---|---|
| Z1 Recovery | below 55 % | very easy, almost no pressure |
| Z2 Endurance | 56 to 75 % | calm, you can talk |
| Z3 Tempo | 76 to 90 % | brisk, you breathe audibly |
| Z4 Threshold | 91 to 105 % | hard, only short sentences |
| Z5 VO2max | 106 to 120 % | very hard, a few minutes |
| Z6 Anaerobic | above 120 % | maximal, seconds to minutes |
What each zone does
Z1: Recovery
Easy spinning promotes blood flow after hard days. It sets no training stimulus but helps recovery. A session like Recovery Spin is meant for that.
Z2: Endurance
Here you build the aerobic base. You ride long, calm and even. This is the zone where most people ride too fast: if you can no longer talk comfortably, you are already above it. Example: Endurance Z2.
Z3: Tempo
Brisk, but doable over longer blocks. Tempo is a bridge between base and harder intervals. Too much of it tires without bringing much, so you dose it. Example: Tempo Blocks.
Z4: Threshold
Close to FTP. Intervals of 5 to 20 minutes raise the power you can hold for long. They are demanding and need recovery. Example: Compact Threshold 3 x 5. More on the range just below in the article Sweet spot training.
Z5: VO2max
Short, hard intervals of two to five minutes challenge heart and circulation strongly. They bring a lot but also cost a lot of recovery. Example: Compact VO2max 4 x 2.
Z6: Anaerobic
Sprints and attacks far above FTP. You hold them only briefly but train speed-strength. Between the attacks full recovery belongs. Example: Compact Sprints 6 x 20.
How much in which zone?
A common rule of thumb: about four of five sessions easy (Z1 to Z2), one of five hard (Z4 to Z6). How that spreads over the week is in the article How often should you train indoors?. Spending more time in tempo and threshold often just makes you tired, not faster.
Heart rate or watts?
Heart rate reacts with a delay: it only rises after a few seconds and is influenced by heat, tiredness, coffee and stress. Watts show you immediately what you deliver. That is why watt zones are more precise for intervals. Heart rate is a good addition, especially for long, easy rides.
How to use the zones in practice
- Use the current FTP: outdated values shift all zones. Test every four to eight weeks.
- Ride easy days really easy: this is the most common mistake. Stay in Z2 even if it feels too easy.
- Hit intervals cleanly: neither clearly below nor above. A smart trainer with target watts helps.
- Listen to your body: zones are a guide. On bad days you may lower the intensity.
In Zombike you get the target watts from your FTP for every session and see in the profile which zones it runs through. You find all sessions under Workouts.
Frequently asked questions
What is zone 2 and why is it so important?
Zone 2 is the calm endurance range at about 56 to 75 % of FTP. Here you train a lot without straining yourself much. That leaves energy for the hard sessions and you build the base.
Can I estimate my zones without a test?
Yes, an estimate is enough at the start. Better is an FTP test, because wrong zones shift the whole planning.
Why does Z2 feel so easy?
Because it is meant to be easy. The stimulus comes from the duration and the repetition over weeks, not from hardness. High intensity does not replace that.
Do the zones apply the same indoors and outdoors?
The percentages do, but indoors the headwind is missing. You sweat more and heart rate is often higher at the same power. Cooling with a fan makes a big difference.
Note: This article is general advice and does not replace medical or sports-science guidance. The zone limits are a guide and may differ slightly depending on the model.
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