The problem with zone charts
You've seen the charts: five colored bars, heart-rate ranges by age, "Zone 2: 114–133 bpm." Then you go run in Zone 2 and it feels suspiciously like Zone 4 — or suspiciously like a walk. So you quietly stop trusting the whole thing.
That's not your fault. Generic zones are built on population averages, and you are not an average. The famous 220-minus-age formula can miss your real maximum by 15 beats in either direction — and every zone built on that guess inherits all of its error.
What's in it for you: zones anchored to your own threshold mean your easy days are genuinely easy (which is where most of your fitness is built) and your hard days genuinely develop speed. No more wondering whether you're going too easy or too hard. The workout tells you the effort; your body confirms it.
Why threshold — and why you can trust it
Lactate threshold is the hardest effort you can sustain for about an hour. It's one of the most replicated concepts in endurance science: individual, measurable, and — the good news — trainable. When your threshold improves, every zone moves with it. That's the whole game.
We're not asking you to take this on faith. The zone structure below is derived from Joe Friel's published zone-setting guidance — the same reference coaches have used for decades — and we link to it in the sources so you can check our work. Why we're different: most apps hand you zones as a black box. We show you the test, the bands, and the label on every number, so you can verify instead of trust.
The 30-minute test
This is the classic field test for finding your lactate threshold heart rate (LTHR). No lab, no mask — just you and a clock:
- Warm up thoroughly — 10–15 minutes easy, with a few short pickups.
- Then go as hard as you can sustain for 30 minutes — a solo time trial.
- Record your average heart rate over the last 20 minutes. That's your LTHR.
Why the last 20 minutes and not the full 30? The first 10 include your ramp-up — heart rate lagging behind effort, settling in. The last 20 are the steady state that actually represents your threshold.
Run it on the road or track for running; on the bike you actually train on for cycling. Do it rested, and pace it evenly — starting too hard and fading hands you a number that isn't your threshold.
Runners get a bonus from the same session: your average pace over the 30 minutes is a working estimate of your threshold pace — the pace you could hold for about an hour.
Cyclists: the 20-minute FTP test
With a power meter, your anchor number is functional threshold power (FTP). Warm up well, ride as hard as you can sustain for 20 minutes, and take 95% of your average power. Why 95%? Because a 20-minute all-out effort runs slightly hotter than what you could truly hold for an hour — the 5% haircut corrects for that.
What makes TriTrain's zones different
Three things. First, every sport gets its own reference — because your running threshold and your cycling threshold are different numbers, and pretending otherwise is how zones stop feeling right:
| Sport | Threshold reference |
|---|---|
| Run | Threshold pace and sport-specific threshold heart rate |
| Bike | FTP and cycling threshold heart rate |
| Swim | A swim-specific pace benchmark (see our swim benchmark guide) |
Second, the bands are Friel-derived — the zone structure from Friel's published guidance, applied per sport. (If you've already set zones in Strava, yours override ours.) One example of what that looks like in practice: in TriTrain, running pace Zone 2 is 114–129% of your threshold pace in seconds per km — comfortably slower than threshold, exactly where easy aerobic work belongs.
Third — and this is the one we're proudest of — every number carries a label, so you always know where it came from:
- Recorded — distance, duration and heart rate supplied by an activity.
- Calculated — zone targets derived from a benchmark you saved.
- Estimated — a provisional guide inferred from your training history.
- Missing — information the app cannot currently establish.
You can start without knowing any of your numbers — effort descriptions and what you already know are enough, and imported activities add evidence over time. When TriTrain's automatic running guide fills a gap from your history, it says Estimated: useful, provisional, and honest about it. An observed pace at a low heart rate is good guidance — it isn't proof of your physiological Z2, and we won't pretend it is.
To be precise: TriTrain uses Friel-derived threshold zones for intensity guidance. It doesn't implement Friel's entire training methodology — the plans combine TriTrain's own progression, workout selection, and recovery adjustments. We'd rather be exact about what we borrow than impressive about what we don't.
When to retest (the good news)
Thresholds move as you train — that's the point of all of this. Retest every 6–8 weeks, after a focused block, or whenever workouts at the top of a zone start feeling like the middle of it. A test repeated under similar conditions (rested, same course, same setup) beats a perfect one-off every time.
Where zones fit in your training
Zones answer one question: how hard should this workout feel? TriTrain handles the rest — what to schedule, how much fits your week, when to back off. And here's a distinction worth holding onto: a race goal tells us where you want to go; a benchmark tells us the right intensity for today. An ambitious finish goal should never automatically make your training paces faster.
In one paragraph: the TriTrain Method builds a plan around your race, experience and available time, then adjusts upcoming training using your completed sessions and recovery feedback. It explains what changed, shows where estimates come from, and makes missing information visible.
Want a plan that adapts around your life? TriTrain builds your training around your race date — swim, bike and run in one place, with recovery built in.
Frequently asked questions
Do I need a heart-rate monitor or power meter?
No. Perceived effort and pace work fine to start — TriTrain begins with effort descriptions and what you already know. Sensors add precision later, but they're not the price of admission.
Why do my zones feel wrong?
Usually one of three things: the anchor number is stale (retest), it came from a formula instead of a test (test), or your run and bike numbers got mixed together (keep each sport's own reference). Zones should feel right within a session or two — if they don't, the input is the problem, not you.
Are my run and bike zones the same numbers?
No — that's why they're sport-specific. Running and cycling threshold heart rates are tested separately and usually differ. Use each sport's own reference.
Is this the full Friel training method?
No. TriTrain uses Friel-derived threshold zones for intensity guidance. The training plans combine TriTrain's own progression, workout selection and recovery adjustments — not Friel's complete methodology.
How often should zones change?
Retest every 6–8 weeks or after a focused block. If the top of a zone starts feeling like the middle of it, your threshold has likely moved — time to test again.
Sources
The zone structure here is derived from Joe Friel's published zone-setting guidance: Joe Friel's Quick Guide to Setting Zones (TrainingBible). Test protocols are paraphrased, not republished — check the original if you want his exact words.