Training zones are bands of intensity defined as percentages of your FTP. Each one asks a different question of your body. The one that matters most is not the hardest — well-trained and elite endurance athletes spend the majority of their training time at low intensity, and most amateurs do the opposite.
The zones, and the job each one does
- Zone 1, active recovery (under ~55% of FTP). Moves blood without adding stress. Not training, and not meant to be.
- Zone 2, endurance (~56–75%). The aerobic base. Builds the machinery that lets you use fat for fuel and recover between hard efforts. Conversational.
- Zone 3, tempo (~76–90%). Genuinely useful in the right dose — and the zone amateurs drift into by accident, where it costs fatigue without buying much.
- Zone 4, threshold (~91–105%). Trains the line itself. Hard, focused, and expensive to recover from.
- Zone 5, VO2max (~106–120%). Raises your aerobic ceiling. Short intervals, full attention.
- Zone 6 and above, anaerobic and sprint. Repeatability of very hard efforts. Matters for racing, rarely the limiter for everyone else.
The percentages differ slightly between models. What does not differ is the logic: every band is defined in relation to your threshold, which is why an inaccurate FTP misplaces all of them at once.
What the research actually says about how to distribute them
A review of training intensity distribution among well-trained and elite endurance athletes found that these athletes typically follow a pyramidal distribution — a high proportion of high-volume, low-intensity training — while some world-class athletes adopt a polarized distribution in certain phases of the season, combining a large share of low-intensity work with a meaningful share of high-intensity work (Stöggl & Sperlich, Frontiers in Physiology, 2015).
Both patterns share the same foundation: most of the time is spent easy. What they do not include is a large middle. The zone amateurs live in is the one the evidence spends least time in.
Why Zone 2 is harder than it sounds
Riding genuinely easy is a discipline. There is always a reason to press: the group, the climb, the segment, the feeling that a slow ride is a wasted ride.
The test is conversational. If you cannot speak in full sentences, you are above Zone 2 regardless of what a number says. Riders who commit to this often report that their hard sessions improve within a few weeks — not because they trained harder, but because they finally arrived at them fresh.
Setting your zones, and keeping them honest
Zones are calculated from your FTP, so they are only as accurate as that number. Two practical consequences: an FTP that is too high makes every zone slightly too hard, which is exactly how riders end up chronically fatigued while believing they are following a plan. And an FTP that is stale after a good block makes everything too easy.
Heart-rate zones are a reasonable backup, but heart rate lags behind effort by a minute or more and shifts with heat, caffeine, sleep and stress. It is a poor guide for short intervals and a decent one for long steady work.
Your numbers, explained the moment you ask.
The gap between knowing this and doing it is where most training goes wrong. Zones drift out of date after a good block. Zone 2 creeps into Zone 3 because the road went up. The plan says threshold on a day your body has other ideas.
Peakfy recalculates your zones from your own rides as your FTP estimate moves, writes each session with the exact power and heart-rate targets that belong to it, and tells you in plain language why today looks the way it does. When you want to know whether Tuesday was really Zone 2 or quietly Zone 3, you ask — and the answer comes from your own data, not a generic table.
Questions riders ask
Keep reading
- What is FTP in cycling, and how do you test it?
- How to increase your FTP: what actually moves the number