CoachingAnswer

WHAT IS LACTATE THRESHOLD IN CYCLING?

By Anthony WalshRoadman CyclingUpdated 20 June 2026

ANSWER

Lactate threshold is the exercise intensity above which lactate accumulates in your blood faster than your body can clear it. There are two thresholds: LT1, the first rise above resting levels that marks the top of true easy riding, and LT2, the point where lactate climbs sharply and the effort becomes unsustainable. LT2 is what your FTP approximates — the highest power you can hold in a quasi-steady state for roughly an hour. The two thresholds bracket your training zones: easy work sits below LT1, hard work pushes toward LT2.

KEY TAKEAWAYS

There are two thresholds, not one: LT1 (the top of easy) and LT2 (the edge of sustainable).
FTP is a field proxy for LT2 — the power you can hold for about an hour.
Below LT1 you can ride almost all day; above LT2 the clock runs out fast.
The two thresholds define where your zones actually sit — which is why training by them beats training by guesswork.

WHO THIS IS FOR

IS THIS YOU?

The rider trying to make sense of zones

You keep hearing about LT1, LT2 and threshold, and want to know what the boundaries physically mean before you train to them.

The polarised-curious amateur

You want to ride easy days easy and hard days hard, and you need to know where 'easy' actually ends.

THE ROADMAN VIEW

Lactate threshold is the single most useful idea in endurance training, and it's quietly misunderstood because most riders think there's one threshold. There are two. LT1 is the top of genuinely easy — the intensity where lactate first lifts off baseline. LT2 is the ceiling — where it runs away from you and the effort has a short fuse. Everything you read about zones is really a story about where these two lines fall.

Lactate itself isn't the villain it was sold as for decades. It's a fuel your body recycles, and the threshold isn't a poison line — it's a marker of the point where production outruns clearance. That distinction matters, because it reframes the goal. You're not trying to avoid lactate. You're trying to push the intensity at which clearance can't keep up to a higher and higher power.

The practical payoff is the reason we build Method plans around it: once you know roughly where LT1 and LT2 sit, the polarised model writes itself. Most of your riding lives below LT1, where you can accumulate hours without digging a hole. A smaller, deliberate share lives at or above LT2, where the adaptations that move the ceiling actually happen. The grey middle — comfortably hard, between the two — is where most amateurs spend their week and where the least adaptation per unit of fatigue lives.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Prof. Stephen SeilerExercise physiologist, originator of the polarised-training framework
Seiler's work anchors training intensity to the two lactate turn-points rather than a single threshold: the bulk of training sits below the first (LT1), a deliberate minority above the second (LT2), and the comfortably-hard middle is the zone to ration. Defining zones by where lactate actually behaves, not by round-number percentages, is the point.
Hear it: Secret To Cycling Fast At A Low Heart Rate | Prof Seiler

PRACTICAL APPLICATION

DO THIS WEEK

Anchor your easy pace to LT1
True endurance riding sits below LT1 — conversational, nose-breathing, a pace you could hold for hours. If your 'easy' rides leave you needing recovery, they're drifting above LT1.
Treat FTP as your working LT2
You don't need a lab. An honest FTP test gives you a usable estimate of LT2. Set your zones from it and retest every six to eight weeks as you get fitter.
Spend less time between the two
The intensity between LT1 and LT2 feels productive and costs a lot for what it returns. Push it to the edges: most volume below LT1, the hard minority near or above LT2.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKEBelieving there's a single threshold.
FIXThere are two. LT1 sets the top of easy; LT2 sets the edge of sustainable. Conflating them is why riders ride their easy days too hard.
MISTAKETreating lactate as a waste product to avoid.
FIXLactate is a fuel your body recycles. The threshold marks where production outpaces clearance — the goal is to raise the power at which that happens, not to fear the molecule.

FAQ

FREQUENTLY ASKED QUESTIONS

What's the difference between LT1 and LT2?

LT1 is the first lift in blood lactate above resting levels — the top of genuinely easy, aerobic riding. LT2 (often called the anaerobic or second threshold) is where lactate rises steeply and the effort becomes unsustainable. LT2 is close to your FTP; LT1 sits well below it.

Is lactate threshold the same as FTP?

FTP is a practical field estimate of your second lactate threshold (LT2) — the highest power you can hold in a quasi-steady state for around an hour. They're used interchangeably in training, but FTP is a usable approximation, not a lab measurement.

How do I find my lactate threshold without a lab?

An honest FTP test gives you a working estimate of LT2. For LT1, the conversational test is reliable: the top of easy is the highest intensity at which you can still hold a full sentence comfortably and breathe through your nose. Both are estimates, but they're enough to set zones.

Can you raise your lactate threshold?

Yes. Consistent aerobic volume lifts LT1, and threshold and VO2 work lift LT2 toward your VO2 max ceiling. Raising the power at each threshold is most of what getting fitter as an endurance cyclist actually means.

Why does lactate threshold matter more than VO2 max?

VO2 max sets the ceiling on your aerobic engine, but lactate threshold determines what fraction of that ceiling you can sustain. Two riders with the same VO2 max but different thresholds will perform very differently over an hour — the one with the higher threshold holds more power for longer.

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