Anaerobic Threshold Calculator

What Is the Anaerobic Threshold Calculator?

The anaerobic threshold, often used interchangeably with lactate threshold, is the exercise intensity at which your body can no longer clear lactate as quickly as it produces it. Training near this point is a powerful way to build endurance. This calculator estimates your anaerobic threshold heart rate from age, resting heart rate and a maximum heart rate formula. For aerobic fitness context, see the VO2 Max Calculator and the 5K Pace Calculator.

How the Calculation Works

The tool first estimates maximum heart rate using your chosen equation. The default Fox and Haskell formula is:

$$\text{HRmax} = 220 - \text{age}$$

Other options are Tanaka, $208 - 0.7 \times \text{age}$, and Nes, $211 - 0.64 \times \text{age}$. You can also enter a tested maximum. The threshold is then computed with the Karvonen method:

$$\text{THR} = (\text{HRmax} - \text{HRrest}) \times \%\text{Intensity} + \text{HRrest}$$

The tool reports the threshold at 85% of heart rate reserve and an anaerobic zone from 85 to 90% of reserve.

Worked Example

A 30-year-old with a resting heart rate of 65 bpm has an estimated maximum of 220 - 30 = 190 bpm. Heart rate reserve is 190 - 65 = 125 bpm. At 85% intensity the threshold is 125 x 0.85 + 65 = 171 bpm. At 90% it is 125 x 0.9 + 65 = 178 bpm, so the anaerobic zone spans roughly 171 to 178 bpm.