What is the anaerobic threshold?

The anaerobic threshold is the exercise intensity where lactate starts building up in your blood faster than your body clears it. Below it you can sustain effort for a long time; above it fatigue sets in quickly. It is often expressed as a heart rate so you can pace training against it.

How is the anaerobic threshold heart rate estimated?

This calculator uses the heart rate reserve method. It estimates your maximum heart rate as 220 minus your age, subtracts your resting heart rate to get your reserve, then puts the threshold at about 85 percent of that reserve added back onto your resting rate. That usually lands near 90 percent of maximum heart rate.

How accurate is the estimate?

It is a guide, not a measurement. Real thresholds vary with fitness, genetics and training, and the 220 minus age formula for maximum heart rate has a wide margin. The accurate method is a laboratory graded exercise test measuring blood lactate or breath gases. Use the estimate as a starting point.

Anaerobic Threshold Calculator

Your anaerobic threshold is the exercise intensity at which your body starts producing lactate faster than it can clear it, so it tips over from mostly aerobic effort into anaerobic effort and fatigue builds quickly. Knowing the heart rate that marks this point helps you train smarter: staying just below it builds endurance, while short efforts above it lift your ceiling. This calculator estimates your anaerobic threshold heart rate from your age and your resting heart rate using the heart rate reserve method. It first estimates your maximum heart rate as 220 minus your age, subtracts your resting heart rate to find your heart rate reserve, then places the anaerobic threshold at about 85 percent of that reserve added back onto your resting rate. It also shows your maximum heart rate and your aerobic threshold at around 70 percent of reserve, so you can see the full picture of your training zones. The result is an estimate that suits most recreational athletes as a starting guide. The only truly accurate way to find your threshold is a laboratory test that measures blood lactate or the gases you breathe out during a graded exercise test, so treat these numbers as a sensible default to refine against how you actually feel.

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Your age

years

Resting heart rate

bpm

171 bpm

estimated anaerobic threshold heart rate

Maximum heart rate190 bpm

Aerobic threshold (70% reserve)151 bpm

Percent of maximum90%

This is an estimate. Your true anaerobic threshold depends on fitness, genetics and training, and is best found by a laboratory lactate or gas exchange test. Use the numbers as a training guide, not a medical measurement.

How it works

The heart rate reserve method starts by estimating your maximum heart rate as 220 minus your age. Subtracting your resting heart rate gives your heart rate reserve, the working range between rest and maximum. The anaerobic threshold is placed at about 85 percent of that reserve added back onto your resting rate, and the aerobic threshold at about 70 percent. Because the method uses your resting heart rate rather than a flat percentage of maximum, it adapts a little to your fitness, but it is still an estimate built on population averages.

Worked example

Take a 30 year old with a resting heart rate of 60 beats per minute. The estimated maximum heart rate is 220 minus 30, which is 190 beats per minute, and the heart rate reserve is 190 minus 60, which is 130 beats per minute. The anaerobic threshold sits at about 85 percent of that reserve, 0.85 times 130 is 110.5, added to the resting 60 for roughly 171 beats per minute, which is about 90 percent of the maximum. The aerobic threshold at 70 percent of reserve works out to 60 plus 91, or 151 beats per minute, marking the easier end of your useful training range.

Related calculators

Max Heart Rate Calculator: your estimated peak.
Target Heart Rate Zone Calculator: training zones.
VO2 Max Calculator: aerobic capacity.
Calories Burned Calculator: energy used in exercise.

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