By Zencalcy Editorial TeamLast reviewed About us
The anaerobic or lactate threshold is the intensity where hard effort starts to build up in the blood faster than your body clears it. Its heart rate marks the top of steady hard training, so it is useful for setting tempo and threshold zones.
Estimate lactate threshold heart rate from age or a time trial.
From max HR: LTHR ≈ 0.85 × (220 − age) From time trial: LTHR = average HR of the last 20 minutes of a 30 minute effort Threshold range ≈ 95–105% of LTHR
The 0.85 factor is a rough population average. A thirty minute time trial is more personal because it measures your own response rather than an age guess, but it should be paced so the final twenty minutes are as even as you can manage.
| Symbol | Meaning |
|---|---|
| age | Your age in years, used for the estimate method. |
| average HR | Average heart rate of the last 20 minutes of a 30 minute time trial. |
At age 40 the estimated maximum is 180 bpm, so the threshold is about 153 bpm and the training range about 145 to 161 bpm. In a time trial, an average of 160 bpm over the last twenty minutes would set the threshold at 160 bpm instead.
The anaerobic threshold, often treated as the point where lactate begins to accumulate faster than the body clears it, is commonly approximated at about 85 percent of maximum heart rate. At this intensity you are working near the top of what you can hold for a sustained period without rapidly fatiguing, so it sits between comfortable tempo and true all out effort.
The 85 percent figure is a population average, not a fixed switch. Trained endurance athletes often reach threshold above 85 percent of maximum, while untrained people may hit it nearer 70 to 75 percent. The body crosses from steady to straining at a personal point, so a percentage of maximum is only a convenient stand in.
Work at or just below threshold, sometimes called tempo or threshold training, raises the pace you can hold before fatigue builds. The method is to spend controlled blocks near that intensity rather than sprinting far above it, because the goal is to push the boundary outward over time. Because the 85 percent landmark is approximate, learn the breathing and effort cues that mark your own threshold.
Continue with the Critical Power Calculator, Heart Rate Recovery Calculator, or the Heart Rate Reserve Calculator — or browse more heart rate & performance tools and all sports calculators.
The first minutes let heart rate rise and effort settle, so the later average reflects a steady hard output rather than a fresh surge. That average is close to the threshold rate for most people.
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Content updated: September 2026