Power and HR zones¶

Zones are how PeakLine translates raw watts and bpm into meaningful intensity buckets. Set them once in Settings → Training zones and every analysis from then on uses them.

Why zones matter¶

Without zones, a workout summary is a wall of numbers: "avg HR 158, max HR 174, avg power 215 W." Useful, but doesn't tell you much about what you trained.

With zones, the same workout becomes: "65% in Z2, 25% in Z3, 8% in Z4, 2% in Z5." That's actionable — you can see whether your "endurance ride" actually stayed in endurance, or whether you slipped into tempo for half of it.

Power zones (Z1–Z7)¶

PeakLine ships with the Coggan 7-zone model, anchored to your FTP:

Zone	Name	% of FTP	What it feels like
Z1	Active Recovery	< 55%	Café spin, very easy
Z2	Endurance	56–75%	All-day pace, full conversations
Z3	Tempo	76–90%	Comfortably hard, short sentences
Z4	Lactate Threshold	91–105%	Race pace, monosyllables
Z5	VO2max	106–120%	3–8 min intervals, no talking
Z6	Anaerobic Capacity	121–150%	30s–3min, very painful
Z7	Neuromuscular	> 150%	Sprints, < 30s

Setting your FTP. Enter it in Settings → Training zones. If you don't know your FTP:

The cleanest test is a 20-min all-out effort; take 95% of average power.
A rougher proxy: average power for a 60-minute hard ride.
A guess: 2.5–3.5 W/kg for recreational riders, 3.5–4.5 for strong club riders, 4.5+ for racers.

You can also override individual zone boundaries if you use a different model (8-zone, sweetspot-centric, etc.).

Re-test seasonally

FTP drifts. After a 4–6 week training block, redo the test. PeakLine flags a stale FTP after 12 weeks with a small reminder on the dashboard.

HR zones (Z1–Z5)¶

The default model is 5-zone Karvonen-style, anchored to your LTHR or max HR:

Zone	Name	% of LTHR	What it feels like
Z1	Recovery	< 81%	Walking pace
Z2	Endurance	81–89%	Long ride pace
Z3	Tempo	90–93%	Sustained moderate
Z4	Threshold	94–99%	Race effort
Z5	VO2max	≥ 100%	All-out intervals

Setting LTHR. Either:

Run a 30-minute time trial; take the average HR of the final 20 minutes as LTHR.
If you only know Max HR, set that and PeakLine will estimate LTHR ≈ 0.95 × Max HR.

If neither is set, the system uses defaults (Max HR = 190, Resting HR = 60). The analysis still works, but zone time is approximate.

Where zones show up¶

Zones drive a lot more than the zone bar chart on the activity page:

Stress Points uses zone multipliers — see Stress Points.
AI Coach references which zones dominated when generating a summary.
Auto-reports appended to your Strava description include a one-line zone summary.
Achievements track "time in Z4+" for some badges (e.g., the "Threshold Crusher" line).

Zone time visualization¶

On each activity, PeakLine shows two stacked bars:

Power zones bar (only if you have a power meter).
HR zones bar — usually wider than the power bar because HR is recorded more often.

Hover any segment to see the exact time spent in that zone, the percentage of total moving time, and the W or bpm range.

A note on "decoupling"¶

If you have both power and HR on the same ride, the gap between them tells a story. In a fresh state, HR tracks power closely. As you fatigue, HR drifts upward for the same power — that's decoupling. A decoupling ratio above ~5% on a steady ride is a strong hint that you're either underfueled, undertrained for the duration, or starting to crack.

PeakLine doesn't compute a single decoupling number (yet), but you can eyeball it from the dual-bar comparison on the activity page.