Almost every number Sequorr shows you traces back to a single value: your lactate threshold heart rate. Your zones are pinned to it. The time you spend in each zone is measured against it. The training load recorded for a heart-rate session is calculated relative to it.
The good news: you don’t need a lab, a treadmill, or a blood draw to find it. A single 30-minute effort, a recent race result, or even a 15-minute run by feel will get you a usable number. This guide walks through how to find your LTHR, where to enter it in Sequorr, and why it’s worth retesting every few weeks as you get fitter.
What Lactate Threshold Actually Is
As you run harder, your muscles produce lactate. At easy efforts your body clears it about as fast as it’s made, so it never builds up. Lactate threshold is the intensity where production starts to outpace clearance — the line between an effort you can hold for a long time and one that quietly forces you to slow down. Cross it, and the clock on how long you can sustain that pace starts ticking.
Two Thresholds: LT1 and LT2
There are actually two thresholds, and confusing them is where most runners go wrong. LT1, the aerobic threshold, sits at the pace where blood lactate first rises above resting levels — usually around 2 mmol/L. That’s the top of your easy running, the effort that keeps easy days genuinely easy. LT2, the anaerobic threshold, is the pace where lactate production overwhelms clearance and the curve turns sharply upward, typically near 4 mmol/L. When a coach, a watch, or Sequorr says “lactate threshold,” LT2 is the number they mean.
Where to Set Your LTHR in Sequorr
Finding your threshold only helps if the app knows about it. In Sequorr, open your profile and go to Settings. Under Training Readiness — the same section where you set your max and resting heart rate — you’ll find the field for your lactate threshold heart rate. Enter the number from your most recent test and save.
The moment you save, Sequorr re-anchors your threshold zone around the new value and uses it as the reference point for the heart-rate-based training load it records on your sessions. There’s nothing else to do. Every future activity is scored against the updated number automatically.
The 30-Minute Test — The gold standard
Warm up 10 to 15 minutes, then run 30 minutes hard and steady — controlled, not a sprint you fade out of. Hit the lap button at the 10-minute mark and average your heart rate over the final 20 minutes. That average is your LTHR. The opening minutes are dropped on purpose, because heart rate takes a few minutes to catch up to effort and would drag the number down. A flat course and a HR strap give the cleanest read.
What you need: a watch or chest strap that records heart rate, and a flat, uninterrupted course. A track or flat route is ideal.
- Warm up easy for 10 to 15 minutes.
- Run hard for 30 minutes — steady and race-like, not a sprint you fade out of.
- At the 10-minute mark of that hard effort, press the lap button.
- Hold the effort for the final 20 minutes.
- Take your average heart rate for that last 20-minute block. That average is your LTHR.
The first 10 minutes get thrown out on purpose. Heart rate lags behind effort in the opening minutes, so averaging the full 30 would undercount your true threshold. The final 20 minutes is where your heart rate has caught up and settled in at the effort — which is exactly what you want to capture.
Shortcut: Estimate From a Recent Race
If you’ve raced in the last six weeks, you can back out your threshold pace without running another hard test. Threshold pace is roughly what a fit runner can hold for about an hour, which for most non-elite runners lands almost exactly at 15K-to-half-marathon race pace. From there:
- From a 5K — add 15 to 25 seconds per mile (9 to 15 sec/km) to your 5K pace.
- From a 10K — add 10 to 15 seconds per mile (6 to 9 sec/km).
- From a half marathon — your race pace is your threshold pace, or within a few seconds of it.
- From a marathon — subtract 20 to 30 seconds per mile (12 to 18 sec/km) from your marathon pace.
Pair that pace estimate with the heart rate you were holding during the race and you have a solid threshold heart rate to start from — no dedicated test required.
No Watch or Race? Use the Talk Test
If you have neither a heart rate monitor nor a recent result, the talk test gives you a rough read in about 15 minutes. Run at the effort where you can get three or four clear words out before you need a breath. Two words is too hard — that’s closer to 5K effort. A full sentence is too easy — that’s closer to marathon effort. Three to four words is the threshold sweet spot.
On a 1-to-10 effort scale, threshold sits around a 7 or 8. It should feel like a pace you could hold for another 20 minutes if someone put a medal at the end — but not for another hour. The talk test is less precise than the 30-minute test, but it travels with you, and it’s a useful gut check mid-workout even when you’re wearing a watch.
Is a Lab Test Worth It?
A graded lab test with blood sampling is the gold standard — it measures both LT1 and LT2 directly instead of estimating them. If you have access and the budget, it’s the most accurate number you can get. But for the vast majority of self-coached runners, the 30-minute test lands within a few beats of the lab result for the cost of one hard workout. Start there. Reach for the lab later, if and when you’re chasing the last percent.
Where LTHR Sits in Your Heart Rate Zones
For most well-trained runners, lactate threshold falls between roughly 85 and 92 percent of maximum heart rate. On a five-zone system, that’s the bottom of Zone 4. Below it, in Zones 2 and 3, you’re burning a heavier share of fat and building your aerobic base. Above it, in Zones 4 and 5, you’re leaning on glycogen and accumulating fatigue fast. Threshold is the hinge the whole system pivots on.
This is also why the “220 minus age” shortcut leads people astray. That formula can miss true max heart rate by 10 to 15 bpm, and because your threshold is a percentage of that max, the error compounds through every zone. Five beats in the wrong direction turns a 40-minute tempo into a VO2 max grind, or into a glorified marathon-pace run. A measured LTHR skips the guesswork and pins the threshold zone where it actually belongs for your physiology.
Workouts That Raise Your Threshold
Lactate threshold improves when you train at or just below it for extended durations. Research on endurance athletes points to a polarized distribution — roughly 75 to 80 percent of weekly volume easy, below LT1, and 15 to 20 percent at or above threshold — as the pattern that raises threshold most. Three workouts do the heavy lifting.
Classic tempo runs
20 to 40 continuous minutes at threshold pace, or within about 3 bpm of your LTHR, book-ended by a 10-minute warmup and cooldown. Start at 20 minutes and add roughly 5 minutes per week until you can hold 40. This is the plainest, most direct threshold stimulus there is.
Interval Strides
3 to 5 reps of 8 to 12 minutes at threshold, with 60 to 90 seconds of easy jogging between them. The short recovery keeps your heart rate from fully dropping, so you can bank 40 to 50 minutes of threshold time even on a day when a continuous tempo feels like too much.
Threshold intervals at 10K pace
3 to 5 reps of 1 mile at 10K pace with 60 seconds rest, book-ended by a 2-mile warmup and cooldown. Faster than a classic tempo, but the short rest holds the threshold stimulus in place.
Build one threshold session into your week from the sequorr training plan. Add a second only if you’re running 50 miles a week or more, and keep the two at least 72 hours apart. In Sequorr, this is the work that drives your Endurance pillar — the threshold dimension of your Running Fitness Score. If you’re putting in the sessions and that pillar isn’t moving, it’s a signal to check your intensity or your recovery.
How Often to Retest
Retest every 6 to 8 weeks during a build phase. Any sooner and you’re mostly measuring noise from heat, sleep, and hydration. Any later and your zones drift out of sync with your real fitness. Three signals tell you it’s time to retest before the six-week mark:
- Tempo runs feel noticeably easier at the same pace.
- A recent race beat your expected time by 30 seconds per mile or more.
- Your heart rate runs 5-plus bpm lower at paces that used to feel hard.
Run the test on a cool morning, rested, at least 48 hours after your last hard workout. A test the day after an interval session captures fatigue, not fitness. And the moment you get a new number, update it in Sequorr the same day. Running your next tempo against last month’s threshold wastes the adaptation you just earned — and leaves your zones lagging behind the runner you’ve become.
The Bottom Line
Your lactate threshold heart rate is the single most important number you’ll hand to Sequorr. It’s the anchor your zones hang on and the reference point behind the load in every session. Test it with a 30-minute effort, back it out of a recent race, or estimate it by feel — then set it in the app and retest every few weeks as you get fitter.
Set the number. Then go run, and let the zones take care of themselves.
