Is the 220 minus age formula useless?

Not useless — it's a starting point. But it is routinely off by 10 to 20 bpm. A field test or 20-minute test is much better.

Do chest straps matter?

For intervals and tempo, yes — wrist optical is noisy on fast pace changes. For Zone 2 the wrist is usually fine.

HRV is a recovery signal, not a training prescription. Use it to decide how hard to push today, not to set your zones.

The Complete Guide to Heart Rate Training

Pace tells you how fast you are moving. Heart rate tells you what that movement is costing you. For amateur endurance athletes who train through varied weather, terrain, sleep and stress, heart rate is the more honest target — and the foundation of every modern adaptive coaching system.

The five zones

Zone	%Max HR	RPE	Feels like	Used for
1 Recovery	50–60%	1–2	Almost nothing	Active recovery, warm-ups
2 Aerobic	60–70%	3–4	Conversational	Base building, long runs
3 Tempo	70–80%	5–6	Comfortably hard	Marathon pace work
4 Threshold	80–90%	7–8	Hard, focused	Lactate threshold
5 VO₂max	90–100%	9–10	All-out intervals	Speed, peak power

Why HR beats pace for most amateurs

It self-corrects for weather, terrain and fatigue. The same Zone 2 effort in summer is slower than in winter — as it should be.
It rewards consistency over heroics. Easy runs stay easy; hard runs are honestly hard.
It catches early overtraining before you feel it. A 10-bpm jump at your usual pace is a signal worth listening to.

When HR lies

Short intervals — HR lags the effort by 30–60 seconds.
Heat, dehydration, caffeine, illness — all push HR up at the same workload.
Optical wrist sensors during fast pace changes — they smooth aggressively.

On those days, switch to RPE. Both are valid; the skill is knowing which one to trust.

How to find your max heart rate

Forget 220 minus age. The most reliable field test: warm up thoroughly, run three to four hard hill repeats of 90 seconds, then on a final repeat sprint flat-out to the top. Your watch will record the peak. Repeat once or twice — it should be the same number.

Calculating your zones

Two main methods:

Percent of max HR — simple, slightly under-cooks Zone 2 for fit athletes.
Karvonen (heart-rate reserve) — adds resting HR to the calculation. More accurate. Zone X = restHR + pct × (maxHR − restHR).

Putting it into a week

A simple, evidence-based week looks like:

Three to four Zone 2 runs
One Zone 4 threshold session
One Zone 5 VO₂max session every 7–10 days
Long run mostly in Zone 2, optionally finishing with a tempo block

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Your zones, computed and updated automatically

KYN sets your zones from your max HR, resting HR and recent races — and prescribes every session in a zone you can actually train in.

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Frequently asked questions

Is the 220 minus age formula useless?
Not useless — it's a starting point. But it is routinely off by 10 to 20 bpm. A field test or 20-minute test is much better.
Do chest straps matter?
For intervals and tempo, yes — wrist optical is noisy on fast pace changes. For Zone 2 the wrist is usually fine.
What about HRV?
HRV is a recovery signal, not a training prescription. Use it to decide how hard to push today, not to set your zones.

Sources & references

Tanaka, H., Monahan, K. D., & Seals, D. R. (2001). Age-predicted maximal heart rate revisited.
Seiler, S. (2010). What is best practice for training intensity distribution?

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