The two zones, in plain terms
| Zone 2 | Sweet spot | |
|---|---|---|
| Power | 56–75% of FTP | 88–94% of FTP |
| Heart rate | 69–83% of threshold HR | Close to threshold HR by the end of an interval |
| Feels like | Easy. You can talk in full sentences | Hard but controlled. A few words at a time |
| Typical session | A long, steady ride | Intervals of 10–30 minutes |
| Fatigue | Low. Can be ridden most days | Moderate. Needs recovery between sessions |
Zone 2 is Andy Coggan’s Endurance level. Physiologists place it at or just below your first lactate threshold (LT1), where blood lactate starts to rise above resting levels. Sweet spot sits between tempo and threshold. It was popularised by coaches and apps such as TrainerRoad because it delivers a lot of training stress per hour without the fatigue of full threshold work.
What the research actually shows
Good endurance athletes ride easy most of the time. Stephen Seiler’s widely cited 2010 review of elite endurance athletes found that roughly 80% of their training is at low intensity, with the rest hard. Very little sits in the middle.
In trained cyclists, polarized beat threshold. In a 2013 crossover study, 12 trained cyclists did six weeks of each approach. With 80% easy and 20% hard training, peak power rose 8% and lactate threshold 9%. A threshold-heavy plan (57% easy, 43% moderate) gave 3% and 2%, even though it involved more hours (Neal et al., 2013). A larger nine-week study of 48 well-trained endurance athletes found the same direction, with the biggest gains in VO2peak and time to exhaustion in the polarized group (Stöggl and Sperlich, 2014). Both studies were small and short, and the polarized group in the second one also trained more hours, so treat the size of the gains with caution.
Zone 2 isn’t magic, though. A 2025 review in Sports Medicine found no good evidence that Zone 2 is better than harder riding for building mitochondria, and noted that harder efforts matter more when total training time is low (Storoschuk et al., 2025).
Zone 2 works because it lets you ride a lot without digging a hole, so you can go properly hard on the days that count. Sweet spot works because it packs a lot of training into little time. The question isn’t which zone is better; it’s how much time you have.
How to split your week
These are sensible starting points, not prescriptions. Adjust them to how you recover and what you’re training for.
- Under 5 hours a week: you can’t ride enough easy hours for volume alone to do much. Make two sessions count, such as one sweet spot or threshold session and one shorter, harder VO2 session, and keep the rest easy.
- 5 to 10 hours a week: one or two hard sessions, everything else in Zone 2. A four-to-six-week sweet spot block is a good option in late winter, as long as the easy days stay easy.
- More than 10 hours a week: roughly 80% easy and 20% hard by time, with long Zone 2 rides at the weekend and two hard days in the week.
The most common mistake is riding every “easy” day a little too hard. That lands you in the middle zone, too tired to go properly hard and not easy enough to recover. Check your power or heart rate on easy days and be strict about it.
The winter trainer problem
Zone 2 indoors is the hardest kind of easy: long, steady and boring. A few things help. ERG mode holds your power in the range so you can’t creep upward. A strong fan keeps your heart rate from drifting with the heat. And a podcast or film on a second screen makes 90 minutes pass.
It also helps to see that the work counts. Indoor sessions and outdoor rides add up to the same training load, so the base you build on the trainer in February is still there in June. Read how training load works, or see how WattsUP plots indoor and outdoor riding on one curve.
Find your numbers
The Zone 2 calculator turns your FTP and heart rate into a Zone 2 range and an 80/20 weekly split. If you don’t know your FTP yet, start with the FTP test guide.
Frequently asked questions
Is Zone 2 or sweet spot better for cycling?
For most riders with five or more hours a week, a week built mostly on easy Zone 2 riding with one or two hard sessions beats a week full of sweet spot. In controlled studies of trained cyclists, that polarized pattern improved peak power and lactate threshold more than threshold-heavy training. Sweet spot is most useful when time is very short or in a focused block before an event.
What is the difference between Zone 2 and sweet spot?
Zone 2 is easy endurance riding at 56–75% of FTP; you can talk in full sentences and ride it for hours. Sweet spot is 88–94% of FTP, between tempo and threshold: hard enough that you can only speak a few words, and usually ridden as 10 to 30 minute intervals.
Is sweet spot the same as Zone 3?
No. Coggan’s Zone 3 (Tempo) is 76–90% of FTP and Zone 4 (Threshold) is 91–105%. Sweet spot, at 88–94%, straddles the top of Zone 3 and the bottom of Zone 4.
Does Zone 2 raise FTP?
Indirectly. Zone 2 lets you ride more hours with little fatigue, which builds your aerobic base. Most riders also need some work near or above threshold to push FTP up, which is why polarized plans keep one or two hard sessions a week.
Can I do Zone 2 on an indoor trainer?
Yes. ERG mode holds your power steady, which makes it easier to stay in Zone 2 than on a hilly road. Indoor rides tend to feel harder at the same power because of heat, so a strong fan helps and heart rate is worth watching.
How do I find my Zone 2?
Zone 2 is 56–75% of your FTP or 69–83% of your threshold heart rate. The free WattsUP Zone 2 calculator works it out from your FTP and heart rate.
Sources
- Neal et al. (2013). Six weeks of a polarized training-intensity distribution leads to greater physiological and performance adaptations than a threshold model in trained cyclists. J Appl Physiol 114:461–471
- Stöggl & Sperlich (2014). Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training. Frontiers in Physiology 5:33
- Seiler (2010). What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform 5(3):276–291
- Storoschuk et al. (2025). Much Ado About Zone 2: a narrative review. Sports Medicine 55(7):1611–1624
- TrainingPeaks: Andy Coggan’s power training levels
- TrainerRoad: What is sweet spot training
This article is general training information, not medical advice. If you have a heart condition, talk to your doctor before starting structured training.