Power is the intensity. Heart rate is the check. The watts you call “threshold” still depend on which lactate definition you mark, so write the definition next to the number.
At a glance
- No hard session in the previous 24–48 hours. Record food, caffeine, and the time of day.
- Zero the power meter. Put a fan on. Optional resting sample, then a 10–15 minute warm-up.
- Stages of 4 or 5 minutes. No rest between stages. Stay seated.
- Start at an easy power. Add 20–30 watts each stage. 25 watts is a solid default.
- Sample in the last 30 seconds. Log watts, lactate (mmol/L), heart rate, RPE, and time.
- Stop once the curve is clearly past 4 mmol/L, or when you can no longer hold the power.
- Print the sheet before you start. A trainer in ERG mode is the cleanest setup. A helper is useful and less essential than on the run.
Who it's for
Cyclists who want a field estimate of lactate threshold from power, with a handheld meter such as a Lactate Plus. A smart trainer that can hold a target in ERG mode is the best venue. A power meter on a stable indoor trainer is the next best. An outdoor ride only works if you can hold steady watts with no stops, junctions, or gusts. Most people should do this indoors.
You need to be able to ride continuously through the warm-up and roughly 30–45 minutes of stages. Solo sampling is realistic on a trainer, because you can sit up and keep the pedals turning. It is still cleaner if someone else handles the lancet.
The result is an estimate tied to this procedure. It is not a laboratory lactate test and it is not a medical assessment. Hour power, FTP, and LT2 are related ideas. They are not the same number, and this page does not convert one into the other. For the physiology behind the curve, see what lactate threshold is.
What you need
- Handheld lactate meter that reports mmol/L, plus 12–15 strips. Check the expiry and close the vial. Rest, the stages, a missed fill, and a spare all use strips.
- Lancets, alcohol wipes, and dry gauze. You need something dry to remove sweat and to discard the first drop. Alcohol alone is not that.
- A towel. Sweat on the finger is enough to push a reading up.
- Heart-rate monitor. A chest strap beats a wrist optical sensor when your hands are on the bars.
- Smart trainer or power meter. ERG mode holds the watts for you. If you don’t have ERG, hold the power meter’s target with gears. Zero the offset the way that meter’s manual describes, before the warm-up. Trainer-estimated power and a crank meter will not agree. Retest on the same power source.
- A fan. Indoor tests overheat. Heat raises heart rate at the same watts and can end the test for the wrong reason. The lactate-versus-power curve can still be usable. Don’t copy heart-rate zones from a heat-stressed test into cool-weather riding without saying so on the sheet.
- The data sheet and a pen, a sharps container, and spare meter batteries. A helper is optional and still worth it. A bottle is fine. Small sips only, and note them.
Follow the meter’s strip insert for error codes, control solution, and temperature range. Don’t leave the vial open between stages.
Before the test
Standardize the day, not just the watts. Lactate and heart rate move with fatigue, glycogen, caffeine, heat, and time of day. Write the conditions down so the next test can match them.
- 24–48 hours easy. No intervals, threshold work, long hard rides, or races. A hard session can move heart rate and lactate, and not always in the same direction. Match the rest, or accept that the curves are not comparable.
- Fueling. Fed or fasted, and the same choice next time. If you eat, finish the main meal a couple of hours before. A small familiar snack is fine if you record it. Carbohydrate availability can lift or lower lactate at the same power, so the meal is part of the protocol.
- Caffeine. Usual dose or none. Write the amount and the timing. It can change heart rate and how hard a wattage feels.
- Hydration. Drink normally through the day. Skip a large bolus right before you clip in.
- Time of day. Use a time you can repeat. A morning test and an evening test are not a clean pair.
- If you are ill, unusually sore, or short on sleep, postpone.
Before stage 1, record temperature, trainer or power-meter model, whether you used ERG, hours since the last hard session, what you ate, caffeine, and the sample site. If you track your cycle, note the phase as context rather than as a correction. Keep the bike position the same. A different saddle height is a different test.
Warm-up
- Optional resting sample after sitting quietly for about five minutes, before you start sweating. Resting capillary lactate often sits somewhere around 0.5–2 mmol/L. Record yours. Don’t chase a “normal” value.
- 10–15 minutes easy spinning, below the planned stage 1 power, at the cadence you will use in the test. You should be able to talk in sentences.
- Three spin-ups of about 10 seconds, quicker cadence, not all-out sprints, with a minute easy between them.
- Three minutes easy, fan already on, then start stage 1 seated.
If you sample at the end of the warm-up, label that row “warm-up.” The resting sample, if you take one, comes before the spin-ups.
The stages
Swipe the table sideways on a small screen.
| Setting | What to do |
|---|---|
| Stage length | 4 or 5 minutes. Both are common for cycling. Four minutes is the default on this page. Five minutes drifts less from a steady lactate and makes the test longer and harder. Use one length for every stage and every retest. A 3-minute stage is sometimes used, and it is more likely to understate lactate at that power. Don’t mix lengths in one curve. |
| Start | A power you can hold while talking in sentences. If you know a power you could hold for about an hour, starting near half of that usually keeps stage 1 close to baseline. If you have no reference, many amateurs start somewhere around 80–120 W, and trained riders higher. As a rough hint, near 1–1.5 W/kg is gentle for a lot of riders and already too high for some. If stage 1 lactate is climbing, the next test starts lower. |
| Step | 20–30 W. 25 W is a practical default. Use 20 W for lighter or less trained riders and 30 W for larger or very fit riders. Keep the step constant. Smaller steps draw a tighter curve and burn more strips. |
| Cadence and position | Pick a cadence you can still turn when it is hard. Many riders land somewhere around 80–95 rpm. The right number is the one you can repeat, not 90 on principle. Stay within about 5 rpm of it, and stay seated. Standing changes the muscles and the lactate. Write the cadence down if it drifted. |
| When to sample | The last 30 seconds, still at the target power if a helper can reach you. If you stop pedaling, later stages can read higher than a sample taken on the bike, because lactate keeps moving out of the muscle after the effort. |
| What to record | Stage, watts, lactate in mmol/L, heart rate at the sample or over the last 30 seconds, RPE, and the clock time. Cadence too, if it moved. |
| Between stages | No rest. In ERG mode, raise the target as the next stage starts. A solo soft-pedal of 15–30 seconds for sampling is acceptable if you do it for the same length on every stage, including the easy ones, and you write “paused” on the sheet. |
With a helper
Keep turning the target power. With about 45 seconds left, sit up enough for the helper to reach a finger or an earlobe. They dry the site, lance, wipe the first drop, and fill the strip in the last 30 seconds. They call out the number. Log watts, lactate, heart rate, RPE, and the time. The next target starts on schedule.
On your own
Plan a 15–30 second soft-pedal at the end of every stage. Insert the strip before you lance, dry the hand, discard the first drop, fill the strip, then click the next ERG target and get back to cadence. Memorize the lactate if you cannot write until the next pause. The soft-pedal is not the stage power. Because the pause is in every stage, the bias is at least consistent. A test with pauses and a test without them are different protocols.
When to stop
Stop at the first of these that happens:
- The curve is defined past the second rise. A practical rule: a value at or above 4 mmol/L and one more stage if you can hold the power, or a reading around 6 mmol/L or higher with the rise already steep. This is not a ramp to failure. You do not need double-digit lactate to mark the usual field definitions.
- You cannot hold the target for the full stage, or cadence collapses and will not come back. Mark the stage incomplete if you bailed early. Don’t treat one minute at that wattage as a finished stage.
- Safety. Chest pain, dizziness, confusion, feeling faint, or pain that is not ordinary effort. Stop. If chest pain, fainting, or confusion does not clear, get medical help.
- Strips or the meter fail. A curve that stops while lactate is still flat does not have an LT2. Lower the start or the step next time.
RPE at 19–20 means you are done even if you wanted another stage. Heat can force a stop before the curve bends. Keep the lactate points you trust, and don’t pretend the heart rates from that room are your cool-weather zones.
How to take the sample
Most bad field tests are bad drops. The meter cannot tell sweat from blood.
- Dry the site with the towel or gauze every stage. Sweat lactate is often higher than blood lactate, so a wet finger reads falsely high. The hand on the bars sweats more than people expect.
- If you use alcohol, let it dry completely. A wet site dilutes the drop.
- Lance the side of a fingertip, or the earlobe if a helper is sampling. The side of the finger is a better site than the pad.
- Wipe away the first drop with dry gauze. It carries more tissue fluid.
- Let a second drop form. A light stroke from the base of the finger is fine. Don’t pinch hard at the tip. Hard squeezing dilutes the sample and can read low.
- Touch the drop to the strip, not the strip to sweaty skin. Let the strip fill. A larger drop is not more accurate. If a meter reports mg/dL, divide by 9 to get mmol/L. A Lactate Plus already reports mmol/L.
- Write the value down before the meter sleeps. On an error or a short fill, resample once and mark “resample.”
- One site for the whole test. Finger and earlobe can disagree. Switching fingers is fine. Switching from finger to ear mid-test is not.
- The lancet goes in a sharps container.
A point that jumps off the curve and comes back on the next stage is a suspect drop. Don’t hinge the threshold on it.
How to read the result
Plot power on the horizontal axis and lactate on the vertical axis. Mark one definition and name it. These markers are all in use. They are not interchangeable. Two tests can only be compared when the protocol and the definition both stayed put.
Swipe the table sideways on a small screen.
| Marker | How to mark it on your plot | What it is, and what it is not |
|---|---|---|
| LT1, first rise above baseline | The first power where lactate steps up from the early flat values and the next stage is higher still. A single blip that falls back is a bad sample or noise. The exact rule varies: visual inspection, about 0.5 mmol/L above the lowest point, or about 1.0. | Also called the aerobic threshold or the first lactate turn point. A common top end for endurance riding. Which delta you use moves the watts. |
| Fixed 2 mmol/L | Where a horizontal line at 2.0 crosses the curve. Interpolate between stages. | A fixed line, not an individual threshold. People with a low or high baseline do not meet it at the same relative intensity. It sometimes sits near LT1 and sometimes does not. |
| OBLA, fixed 4 mmol/L | Where a horizontal line at 4.0 crosses the curve. Interpolate. | Onset of blood lactate accumulation, as a fixed concentration. Easy to repeat. Often near the second threshold. It is not the same thing as maximal lactate steady state, and some riders’ second threshold sits well below or above 4 mmol/L. |
| D-max | The point on a fitted curve farthest from a straight line joining the first point to the last. A hand sketch uses the biggest gap you can see. A formal D-max uses perpendicular distance to a smoothed curve. | One mathematical estimate. A long flat start often pulls original D-max down, below a 4 mmol/L marker. |
| Modified D-max | The same idea, with the straight line starting where lactate first leaves baseline rather than at stage 1. Not every spreadsheet uses the same starting point. | Often closer to a 4 mmol/L or second-threshold region than original D-max. Still an estimate, still dependent on the fit. |
| IAT | Not available from this protocol alone. A formal individual anaerobic threshold uses lactate during the steps and clearance afterward. | Don’t relabel a visual bend as IAT. Call a bend you judged by eye “visual LT2.” |
| Visual LT2 | Where the shallow rise becomes a steep one, after LT1. | The practical field marker when you are not running a curve fit. The idea behind LT2 is maximal lactate steady state: the highest power where lactate would stay nearly flat across a long effort. MLSS needs several constant-power bouts to confirm. One incremental test estimates it. |
Avoid the bare phrase “anaerobic threshold” on the sheet. It has meant LT1, a fixed 4 mmol/L, and LT2 in different books. Stage length, sample site, pauses, and the pre-ride meal all move the curve. A handheld meter is noisier than a lab analyzer, so a few tenths of a mmol/L of wobble is not a breakpoint.
Interpolation
If 250 W reads 3.1 mmol/L and 275 W reads 4.6, then 4.0 is (4.0 − 3.1) / (4.6 − 3.1) = 0.9 / 1.5 of the way from 250 to 275, which is 15 W, so about 265 W. Use the same method next time. Rounding both tests to the nearest stage can invent a 25 W “gain.”
An example curve
The watts below are invented teaching numbers. They are not a target and not a description of a trained cyclist. Use them to see how the markers separate, then throw them away and plot your sheet.
On this example, lactate stays near 1.0–1.3 mmol/L through 175 W. A visual first rise is at 200 W (1.6 mmol/L), and the next stage keeps rising. A fixed 2.0 line falls between 200 W (1.6) and 225 W (2.2): (2.0 − 1.6) / (2.2 − 1.6) of the 25 W step, about 217 W. First-rise LT1 and the 2 mmol line are close here. They are not close on every real curve. Check yours.
A fixed 4.0 line is about 265 W, from the interpolation above. A hand sketch of original D-max — the biggest vertical gap between the curve and a straight line from the first point to the last — sits lower, near 225 W. A modified sketch that starts the line at the first rise moves that marker up near 250 W, closer to 4 mmol/L and still not the same wattage. Treat the sketch as a way to see the gap. A spreadsheet fit will shift it.
Zones from your test
Swipe the table sideways on a small screen.
| Zone | Name | How to set it | What it’s for |
|---|---|---|---|
| 1 | Recovery | Clearly below LT1. Use a power that sat on the flat baseline stages. | Recovery spins. |
| 2 | Endurance | Up to the LT1 power you marked. | Long aerobic rides. |
| 3 | Tempo | Above LT1 and below the LT2 band. | Steady, comfortably hard riding. |
| 4 | Threshold | A narrow band at the LT2 power: that wattage and, if you want a range, the stage just below it. | Threshold repeats. |
| 5 | Above threshold | Above LT2 power. | Short intervals. |
Prescribe power. Heart rate from the test is a secondary check. It drifts upward across a long ride, and a hot room or a fan that died will move it without a change in fitness. A 4-minute stage heart rate is often lower than the heart rate at the end of a long threshold rep at the same watts. These zones are not a Coggan FTP scheme. Don’t multiply them by an FTP you measured on a different day and expect the labels to survive.
Plot the curve before you name the zones. Compare a later test only when stage length, watt step, power source, sample site, meal pattern, and definition match.
Data sheet
Cycling lactate step test
Print this page before the test. The blank sheet starts on a new page, with room to write. Conditions first, stage rows during the ride, markers after you plot.
| Date | |
|---|---|
| Time of day | |
| Trainer or power meter | |
| ERG mode (yes / no) | |
| Temperature | |
| Fed or fasted | |
| Caffeine | |
| Hours since hard session | |
| Meter and strip lot | |
| Sample site | |
| Stage length | |
| Start and step | |
| Cadence target | |
| Sampling pause |
Swipe the table sideways on a small screen.
| Stage | Intensity | Lactate | HR | RPE | Time |
|---|---|---|---|---|---|
| Rest | |||||
| Warm-up | |||||
| 1 | |||||
| 2 | |||||
| 3 | |||||
| 4 | |||||
| 5 | |||||
| 6 | |||||
| 7 | |||||
| 8 | |||||
| 9 | |||||
| 10 |
Intensity is power in watts. Lactate is mmol/L. RPE is Borg 6–20: 6 is no exertion, 9 very light, 11 light, 13 somewhat hard, 15 hard, 17 very hard, 19 extremely hard, 20 maximal. Time is the clock time at the sample. Add a row if you need an 11th stage.
| Marker | Definition used | Intensity | HR |
|---|---|---|---|
| LT1 | |||
| LT2 |
| Notes |
|---|
This is a practical guide for athletes who already use a handheld lactate meter. It is not medical advice. Capillary sampling involves blood: follow the meter manual, use a fresh lancet, and put used lancets in a sharps container. Skip the test if you are ill. Stop for chest pain, dizziness, or feeling faint. If you use anticoagulant medication, have a bleeding disorder, or have been told to avoid hard tests, check with a clinician before finger-sticking through a hard session.