What is lactate threshold?

Lactate threshold is the exercise intensity at which lactate starts to accumulate in the blood faster than it can be cleared. It closely corresponds to FTP in cycling and is a key determinant of endurance performance.

How do I do a 30-minute HR test?

Warm up for 10-15 minutes, then ride as hard as you can sustain for 30 minutes. Record your average heart rate for the last 20 minutes. This is your approximate LTHR.

Is LTHR the same as FTP heart rate?

Very close. LTHR and FTP heart rate are essentially measuring the same threshold from different perspectives (cardiac vs muscular). They should be within 2-3 bpm of each other.

BikeCalcs

Threshold Calculator — Lactate Threshold from Test Data

Find your lactate threshold from heart rate or power test data.

Test Method

Average HR (last 20 min)

How We Calculate This

Threshold Determination

HR method: Average HR during the last 20 minutes of a 30-minute all-out effort approximates LTHR
20-min power: FTP = 95% of 20-minute average power
60-min power: FTP = 60-minute average power (direct measurement)

Frequently Asked Questions

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TSS Calculator

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Last updated: 2025-02-20

All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.