§ 01 — The premise
A plan is only as good as the threshold it is built on.
LT1 and LT2 come off that athlete's lactate curve. Zones follow, every session is written in them, and each one comes back with how it went. No test yet? Start from a field effort, labelled as an estimate.
§ 02 — The test
One test. Two thresholds. One number to plan from.
Steady stages, each a little harder, with a lactate sample after each. The samples make a curve; LT1 and LT2 are read off it.
duro runs the published methods on your curve and shows every estimate. It proposes one value per threshold; the coach keeps or corrects it.
- LT1Aerobic threshold
- Where lactate first rises above resting. Below it is truly easy. On the bike and run, it sets the top of Z2.
- LT2Second threshold
- Where lactate builds faster than you clear it. The step test's estimate of MLSS.
- ReferenceFTP · threshold pace · LTHR
- The planning number, set from LT2 and kept or corrected by the coach. Zones are cut from it.
| Stage | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| Power | 160 W | 190 W | 220 W | 250 W | 280 W | 310 W | 340 W |
| Lactate | 0.9 | 1.1 | 1.5 | 2.2 | 3.4 | 5.8 | 9.1 |
| Heart rate | 115 | 128 | 140 | 152 | 163 | 174 | 182 |
Each dot is one method's reading of the same samples. They disagree, and the coach should see that. The lines are what went on file: LT1 243 W, reference 285 W.
Limits: at least three stages, five recommended. Compare tests only if they used the same protocol; duro does not check.
§ 03 — The pipeline
From one test to a week of training
dūrō.
Klára NovákováTriathlon · A race 25 Oct · run 4:12 /km · swim 1:38 /100 m on file
Sample data
- Fill in data
- Generate plan
- Add new test
- Review plan
Step 3 · Add new testNew test added
Step 1 · Test dataPick a starting point, then fill in the bike.
01
Input
A step test with a lactate sample per stage. No test yet? A field effort gives a labelled estimate.
02
Define
LT1 and LT2 come off the curve. A reference value per sport is set from LT2, and five zones from that. In power and pace zones, Z2 ends at LT1 when it is on file.
Z1Z2Z3Z4Z5
03
Synthesise
Mark races A, B or C. The plan is built backward from each A race.
04
Read back
Each session comes back with what happened and how it felt, beside the plan. Weekly load shows by discipline and zone.
§ 04 — One plan. Two realities.
Coach
Build from the curve, adjust from the load.
Enter the test. Thresholds, zones and session loads follow.
LT1243 W
LT2285 W
ZonesZ1 – Z5
Athlete
Open the app. See today. Go.
One workout at a time, in your zones. Feedback in ten seconds.
TodayThreshold 4 × 8'
TargetZ4 · 270–290 W
Duration1:10
§ 05 — The next session
Set the next session from all three.
A Tuesday on the dashboard, and what the coach does with it.
- PrescribedTuesday · from the plan
- Threshold 4 × 8' at 270–290 W, Z4. 1:10 total.
- What happenedFrom the activity
- 1:02. Reps at 281, 278, then 262 W; rep four stopped early. HR 170 by rep three, above LT2's 165.
- How it feltFrom the athlete · one tap
- RPE 8/10. Feel 2/5. “Legs flat from Sunday's long ride.”
What changes next. Thursday becomes 90' in Z2; the 4 × 8' moves to Saturday. The reference stays at 285 W.
The call is yours. duro lays out all three; it does not move the plan on its own.
§ 06 — For the athlete
Today's session, in your own numbers.
One workout at a time, in your units. One tap to say how it went.
Tue 23 Sep · Bike06:30
Threshold 4 × 8'
How hard was that?
| Zone | Power | Heart rate |
|---|---|---|
| Z1 | < 157 W | < 141 |
| Z2 | 157–242 W | 141–148 |
| Z3 | 243–259 W | 149–156 |
| Z4 | 260–302 W | 157–164 |
| Z5 | 303 W and up | 165 and up |
Cut from the reference, 285 W. Z2 ends at LT1, 243 W: a measured ceiling, not a percentage. Heart-rate zones come from threshold HR, 165 bpm.
- TestFirst, and when the plan needs it
- A step test with your coach or a clinic. No test yet? A 20-minute bike or 30-minute run effort gives a labelled estimate.
- TrainEvery day
- Open the app, see today. Power, pace or heart rate.
- ReportAfter each session
- One tap for effort, one for feel, an optional note.
§ 07 — Questions
The ones people actually ask.
- Do I need a lactate test?
- Not to start. A 20-minute bike or 30-minute run effort gives an estimated threshold, about ±10%. The step test makes it precise.
- Do I need a lab?
- No. A portable analyser, a track, treadmill or erg, and a second person to take samples. Lab, clinic or coach: duro takes the numbers.
- What if I do not have a power meter?
- Test on pace. Watts, pace per km or per 100 m all work. Heart rate works too, as a last resort: it lags and drifts.
- What is the difference between LT2, FTP and MLSS?
- MLSS (maximal lactate steady state) is the true boundary, rarely measured. LT2 is the step test's estimate of it. FTP is the planning number duro sets from LT2.
- How often do I retest?
- When the curve has likely moved: a new phase, or hard sessions feel easy. No reminders. Old sessions keep the thresholds they were written with.
- What happens between tests?
- The plan runs on your last test. Nothing recalculates on its own; the coach adjusts or you retest.
- What does duro not do?
- No fitness, fatigue or form score. No race predictions. No automatic threshold changes. No protocol check between tests.
Not shipped — where duro is going
A plan should not be set in stone. It should live with the athlete.
Today a coach makes that call. duro shows what to read; it does not move the plan.
We are building toward a plan that adapts to sleep, sessions, feel and blood work. Not in the product yet. Everything above the dashed rule is.
Not a coach replacement. The coach still makes the call.
§ 08 — Get in
Your athletes' tests, plans and feedback, in one place
Invite-only for now. Leave your email; we will write when a place opens.
Coaches
Your squad, one screen
Enter tests, write plans, read what comes back.
Athletes
Your numbers, your plan
Your thresholds, zones and plan. With a coach or self-coached.