Zones

Zones out of blood, not a percentage.

Most platforms take a number you estimated and cut it into fifths. Here the two thresholds are measured, and everything downstream is anchored to them.

🎁 Start your 2-week free trialAll featuresLaChart for athletes →
Zones · Power · HR✎ Edit
Z1175–315 W71–127
Z2315–350 W127–141
Z3350–415 W141–159
Z4415–432 W159–165
Z5432–457 W165–174

Power, pace and heart rate together

Five zones generated from the thresholds you just measured, each with its power or pace band and the heart rate that went with it on test day. Ready to paste into whatever the athlete trains with.

Thresholds
LT1
350W
1.9 mmol · 141 bpm
LT2
415W
4.0 mmol · 159 bpm

The two numbers everything hangs off

LT1 is where lactate first lifts off baseline; LT2 is the highest intensity you can hold at a steady lactate. Load, categories, time in zone and the retest nudge are all computed from those two.

Time in zonesLT2 415 W · 2h24m
28%
22%
11%
30%
Z1
41m
28%
Z2
31m
22%
Z3
16m
11%
Z4
43m
30%
Z5
13m
9%
At LT2 · 43m

Reported back the same way

Time in zone is minutes below LT1, at LT1, between, at LT2 and above — the same definition for every athlete, so a coach comparing two people is comparing the same thing.

Threshold trend
LT1 & LT2 over 8 tests
LT2 · THRESHOLD
415 W
▲ +12 W
LT1 · AEROBIC
350 W
▲ +8 W

A nudge when they have moved

When weeks of sessions agree that a threshold has shifted, the app says so, says how confident it is, and says why. Zones stop describing you long before you notice on your own.

The rest of it

Other features

Two weeks, nothing charged today

Connect a device, enter a test, and see your own numbers in it. Cancel whenever.

Start free