You did the test. Now turn it into the seven zones you'll actually train in — by pace, by power and by heart rate, depending on the sport and on what you measured. It's the same table I use with my athletes.
Each sport uses a different test and a different metric. Pick one and we'll walk you through it.
More than one test is valid and they all get you to the same place. Pick the one you did — the maths changes depending on which.
If you have more than one metric, trust them in this order: power > pace > heart rate. HR lags behind the effort and drifts with heat, sleep and caffeine — it's the backup, not the main signal.
Having the numbers is half of it. The other half is knowing which session grows each zone — how to build a Z2 that's more than easy miles, the marathon-pace session that justifies Zone X, and what a real threshold set looks like. We'll email you the full guide.
The full PDF guide: the sessions for every zone, for swimming, cycling and running. One email, nothing else, and you can unsubscribe whenever you want.
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The same ones I use with my athletes, built on this zone structure.
Running plans are organised by race distance rather than by zone — pick your distance in the running plans, and the zones you just calculated are already built into them.
The model is polarised 80/20: roughly 80% of your volume stays easy and 20% is genuinely hard. On top of that base, two zones get extra granularity, because folding them into their neighbours hides something that matters.
Zone X is the top half of Zone 2 — near enough your marathon pace. It gets its own name because it accumulates a lot more fatigue than low Z2 without returning much more aerobic benefit. It's the zone most people overtrain in without deciding to: you head out easy, you feel good, the pace settles a few seconds quicker on its own, and you arrive at your quality day with nothing in your legs.
Zone Y is the bottom of Zone 4. The real Z4 adaptations show up higher in the zone, so Y on its own is a lighter stimulus than the label suggests.
There is no single table. Power, pace and heart-rate zones don't land on the same percentages, and they aren't the same between sports either: Zone 2 starts at 70% of your FTP on the bike, 76% of threshold velocity running, 81% of your LTHR, and 84% of your critical speed swimming. The calculator uses whichever table applies to your case.
One detail that gets miscalculated constantly: pace percentages apply to velocity, not to minutes per kilometre. Applying 76% directly to a 4:00/km pace gives 3:02/km — faster than your threshold, for a zone that should be slower. Every zone comes out inverted, and every one of them looks perfectly reasonable.
Every 2 to 3 months if you're training consistently. Sooner if the prescribed sessions start feeling easy, or if your cardiac decoupling at threshold paces drops. After injury, illness or a long break: two easy weeks back into load, then the test — and expect a lower number. Resetting the expectation is part of the process.
An out-of-date threshold doesn't move one zone. It shifts all seven by the same margin.