Zonas de Frequência Cardíaca Explicadas
A heart rate zone number on its own tells you almost nothing. "Zone 2" is a label from a particular zone system, anchored to a particular reference point in your physiology — and several systems in common use share the same numbers while meaning genuinely different intensities.
So two runners who both say "I did a zone 2 run this morning" may have done quite different sessions. Different enough that one was recovering and the other was accumulating fatigue.
Before any zone number means anything you need two facts about it: what the boundaries are a percentage of, and how many zones are in the scheme. The first matters far more than the second, and almost nobody states either.
The anchor: what your zones are a percentage of
Every zone table is drawn relative to one reference number. Change it and every boundary moves.
| Anchor | How the boundaries are set | Good for | Where it goes wrong |
|---|---|---|---|
| Maximum heart rate | A share of the highest heart rate you can reach | Needs one number. The default on most sports watches | A ceiling is not a performance marker, and the fraction you can sustain varies enormously. From an age formula, every boundary inherits the guess |
| Heart rate reserve | A share of the range between your resting and maximum rates | Accounts for a low resting rate, so a modest improvement on the above | Built on the same estimated ceiling, and resting rate moves with sleep, illness and load |
| Lactate threshold heart rate | Boundaries placed relative to your threshold heart rate | Sits on a real physiological transition, and moves as your fitness moves | Needs a threshold figure you trust, and it drifts as you train, so it needs re-checking |
| Threshold pace or power | The same idea in speeds or watts rather than beats | Immune to heart rate lag, heat and cardiac drift. Better for short intervals | Pace is distorted by hills, wind and surface. Power needs a meter |
| Perceived effort and the talk test | Each zone described by how it feels and how easily you can speak | Needs no equipment, and sanity-checks everything above | Subjective, and poor at separating "comfortably hard" from threshold on a good day |
The count: three zones, five zones, seven zones
On top of the anchor sits a second translation problem. Zone schemes do not all have the same number of zones, and the numbering does not map across.
- Three-zone models split training at the two physiological turn points — below the first, between the two, above the second. This is the language of polarised training.
- Five-zone models are the common presentation on watches and in plans written for recreational athletes.
- Six and seven-zone models come mostly from cycling, and separate anaerobic from neuromuscular work at the top end.
Here is the collision. In a three-zone model zone 2 is the band between the thresholds — sustained, uncomfortable, the effort a tempo run lives in. In a five-zone model zone 2 is easy aerobic work you could hold all day. Somebody's zone 2 is somebody else's zone 3 or 4.
So "run in zone 2" is an incomplete instruction until you know which scheme wrote it. For the five-zone usage, what zone 2 actually refers to covers the definition and the zone 2 guide covers how to train there.
Why the anchor matters more than the count
This is the part most zone explainers leave out, and it is the reason this page exists.
Your maximum heart rate barely responds to training. It is largely set by your physiology, it drifts down slowly with age, and getting fitter does not raise it. Train hard for a year and it will be roughly where it was.
Your lactate threshold does respond to training. The intensity you can hold before lactate accumulates faster than you clear it is one of the things endurance training actually changes, on a timescale of weeks. Your lactate threshold is the moving part of your aerobic profile.
Put those two facts together and the consequence is awkward. A zone table anchored to your maximum heart rate is anchored to the one number your training does not move. As you get fitter your real easy-to-hard boundary rises, but the table does not, because the ceiling it is divided from has not changed. It slowly stops describing you. A threshold-anchored table tracks the change, because the thing it is anchored to is the thing that moved.
There is a quieter second problem. Two athletes with the same maximum heart rate can hold threshold at quite different fractions of it, and the better trained one holds it higher. So a percentage-of-maximum table guesses twice: at the ceiling, and at where your threshold sits beneath it. If an age formula produced your ceiling, age-based zone calculation explains what that estimate is and is not.
If your zones look wrong on your watch
Suspect the settings before your fitness. Several interacting things decide your zone table — the stored maximum, which model the boundaries come from, whether anything updates them automatically, and the fact that zones are often stored per sport. Fixing one and not the others is why the problem comes back. The four reasons your Garmin zones are wrong works through them in the order that saves the most time.
One caveat about finding a true maximum: it takes an all-out effort, which is not something to do casually. This is not medical advice. If you have any cardiac history or symptoms, or you are coming back from illness or a long layoff, speak to a doctor before attempting a maximal test.
Saying what you mean
Three facts make a zone number meaningful: the scheme (three zones, five or seven), the anchor (maximum, heart rate reserve, threshold heart rate, or pace and power), and where that anchor came from — measured, estimated by your watch, or calculated from your age. Those are not the same quality of number.
"Easy run, zone 2 of five, threshold-anchored, threshold measured in March" means something. "Zone 2 run" does not.
Frequently asked questions
What are heart rate zones?
Heart rate zones are bands of training intensity, each defined as a range of heart rates relative to a reference number — usually your maximum heart rate, your heart rate reserve or your lactate threshold heart rate. They turn "go easy" and "go hard" into something you can check on your wrist.
Is zone 2 the same in every system?
No, and that is the most common source of confusion. In a five-zone model zone 2 is easy aerobic running; in a three-zone model zone 2 is the band between your two thresholds, which is far harder. Always ask how many zones the plan is written for.
Should my zones be based on max heart rate or lactate threshold?
Lactate threshold, if you have a figure you trust. Maximum heart rate barely changes with training, so zones built on it stay still while your fitness moves. Threshold-based zones follow your fitness, because threshold is one of the things training actually shifts.
How many heart rate zones should I use?
Whichever number your plan is written in, because the count matters far less than the anchor. Three zones are enough to control the easy-hard balance across a week; five or seven give finer labels for interval work without making the boundaries any more accurate.
Do I need a lab test to set my zones?
No, but a measured threshold is the most reliable anchor available. A lab test with blood samples is the reference standard, a well-executed field test is a reasonable substitute, and an age formula is a placeholder until you have something better.
Why do my easy runs show as a higher zone than they felt?
Usually the anchor rather than the effort. Heat, dehydration and cardiac drift all lift heart rate at the same pace — but if easy runs read hard consistently, the stored maximum or the zone model underneath is the likelier explanation.
Make the zones describe you, not an average
A zone table is only as honest as the number it is divided from, and a percentage of an estimated ceiling is two guesses stacked on each other. Lactate Training builds and adapts your plan around zones anchored to your lactate threshold rather than an estimated maximum, using your synced Garmin and Strava activities.