CoachingAnswer

HOW DO I TEST MY LACTATE THRESHOLD FOR CYCLING?

By Anthony WalshRoadman CyclingUpdated 10 July 2026

ANSWER

The gold standard for lactate threshold testing is a graded exercise test with blood sampling every 3-5 minutes, identifying the intensity where blood lactate rises above 2 mmol/L (LT1) and where it accumulates rapidly above 4 mmol/L (LT2/OBLA). Field alternatives include a 30-minute self-paced time trial where average power approximates LT2, or heart rate deflection analysis during a ramp test. Lab testing costs £80-150 and provides the most accurate data; field tests are free but require honest effort and good pacing.

KEY TAKEAWAYS

LT1 (aerobic threshold, ~2 mmol/L) marks the top of Zone 2; LT2 (OBLA, ~4 mmol/L) closely approximates FTP.
A lab graded test with blood sampling every 3 minutes gives the most precise result — expect to pay £80-150.
A 30-minute maximal time trial provides a practical field estimate of LT2 without lab equipment.
Retest every 8-12 weeks to track whether your thresholds are shifting with training.

WHO THIS IS FOR

IS THIS YOU?

Riders who suspect their FTP estimate is wrong

Your training zones feel too hard or too easy, and you want an independent measure of threshold that does not rely on a single test protocol.

Masters cyclists wanting precise Zone 2 boundaries

You want to train aerobically without drifting into tempo, and need to know exactly where your LT1 sits to set accurate easy-ride targets.

THE ROADMAN VIEW

A lab lactate test is one of the best investments a serious amateur can make. It gives you two numbers — LT1 and LT2 — that anchor your entire training structure. Most riders are guessing at their Zone 2 ceiling, and a significant number are training too hard on easy days because their estimated threshold is wrong.

If the lab is not an option, a flat-out 30-minute time trial on a turbo trainer gives a solid LT2 estimate. The key is genuine maximal effort — if you finish and feel you could have gone harder, the number is too low. It is not a comfortable test. That discomfort is the point.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Prof Stephen SeilerExercise physiologist, University of Agder
The first lactate threshold (LT1) is the most important intensity boundary for endurance athletes because it defines the ceiling for truly aerobic training. Athletes who train above LT1 on their easy days accumulate unnecessary fatigue without additional aerobic stimulus. Identifying LT1 through blood lactate testing allows athletes to calibrate Zone 2 with precision rather than guesswork.

PRACTICAL APPLICATION

DO THIS WEEK

Book a lab lactate test for definitive numbers
Search for sports science labs or university testing centres near you. A graded exercise test on a cycle ergometer with blood lactate sampling every 3 minutes typically costs £80-150 and takes about an hour including warm-up. Ask for both LT1 and LT2 values expressed as power (watts) and heart rate.
Run a 30-minute field test as a practical alternative
Warm up for 15 minutes with two 30-second efforts to open up the legs. Then ride as hard as you can sustain for 30 minutes on a flat course or indoor trainer. Your average power for the 30 minutes closely approximates LT2. Take 95% of that value for a conservative FTP estimate. Record average heart rate for the effort — this is your LT2 heart rate.
Set training zones from the results
Zone 2 sits below LT1 (the first threshold). Sweet spot falls between 88-94% of LT2 power. Threshold intervals target 95-105% of LT2. Having both thresholds means you can train with precision rather than broad estimates — particularly valuable for the easy rides that make up 80% of a well-structured plan.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKETreating FTP and lactate threshold as identical.
FIXFTP is a functional estimate of the power you can sustain for roughly an hour. LT2 is a physiological marker. They correlate closely but are not the same measurement. A lab test gives you the physiological data; an FTP test gives you the practical training number.
MISTAKETesting after heavy training or without proper rest.
FIXTake two easy days before any threshold test. Fatigue suppresses performance and produces artificially low results that set your zones too conservatively.
MISTAKEOnly testing LT2 and ignoring LT1.
FIXLT1 defines the top of your properly aerobic zone. Without it, you are guessing at Zone 2 intensity. Specifically ask for both thresholds if doing a lab test.

FAQ

FREQUENTLY ASKED QUESTIONS

How much does a lactate threshold test cost?

In the UK, expect to pay £80-150 for a graded exercise test with blood lactate sampling at a sports science lab or university. Some high-end bike fitting studios also offer the service. In the US, costs range from $100-200. It is a one-off expense that pays for itself in training precision.

Can I test lactate threshold at home?

Portable lactate analysers (such as the Lactate Pro 2) cost around £300-400 and allow home testing with finger-prick blood samples. You would need to design a graded protocol with 3-5 minute stages at increasing power, sampling at the end of each stage. It is feasible but requires some knowledge of test design.

Does lactate threshold change with age?

Yes, but less than VO2max. Lactate threshold as a percentage of VO2max can actually improve with consistent training, even as absolute VO2max declines. This is one reason well-trained masters cyclists can maintain strong endurance performance — their threshold remains close to their (declining) ceiling.