What is the Anaerobic Threshold?
The anaerobic threshold (AT) — also called the lactate threshold — is the exercise intensity at which your body shifts from aerobic (oxygen-based) energy production to anaerobic metabolism. Beyond this point, lactic acid accumulates faster than it can be cleared, causing the characteristic burning sensation in muscles during intense exercise.
According to the anaerobic threshold formula used in this calculator, your anaerobic heart rate should be around 85% of your maximum heart rate:
Anaerobic Heart Rate = Maximum Heart Rate × 0.85
The full anaerobic zone spans 80–90% of your maximum heart rate.
Heart Rate Training Zones
Your heart rate during exercise falls into one of five zones, each with different physiological effects:
| Zone | % of Max HR | Effect |
|---|---|---|
| Recovery | 50–60% | Active recovery, warm-up |
| Endurance | 60–70% | Base fitness, fat burning |
| Aerobic | 70–80% | Cardiovascular improvement |
| Anaerobic ★ | 80–90% | Speed, muscle, bone density |
| VO₂ Max | 90–100% | Maximum effort, peak power |
Training in the anaerobic zone (80–90%) helps you lose weight faster, build lean muscle, and improve bone density. However, it requires adequate recovery — always balance hard sessions with easier days.
Formulas Behind the Calculator
The calculator uses three validated formulas to estimate your maximum heart rate (BPMmax), from which the anaerobic threshold is derived.
Fox & Haskell Formula (default)
The classic and most widely used formula:
BPMmax = 220 − age
Nes Formula
Validated in a large Norwegian study, considered more accurate for middle-aged adults:
BPMmax = 211 − (0.64 × age)
Tanaka, Monahan & Seals Formula
Based on a comprehensive meta-analysis, recommended for both men and women:
BPMmax = 208 − (0.7 × age)
Reverse Calculation
You can also use this calculator in reverse mode: if you know your anaerobic threshold heart rate (e.g., from a lab test), enter it and the calculator will estimate your expected age according to each of the three formulas.
Frequently Asked Questions
What heart rate is anaerobic?
Your anaerobic heart rate is approximately 85% of your maximum heart rate. The full anaerobic zone runs from 80% to 90% of your max HR. For a 30-year-old using the Fox & Haskell formula: max HR = 190 bpm, anaerobic threshold ≈ 162 bpm, anaerobic zone = 152–171 bpm.
How do I measure my actual anaerobic threshold?
The most accurate method is a laboratory lactate threshold test. For a field estimate, you can use the talk test: your anaerobic threshold is roughly the intensity at which you can no longer hold a full conversation during exercise.
Which formula should I use?
The Fox & Haskell formula (220 − age) is the most recognizable and is used by most fitness trackers. The Tanaka formula is considered more scientifically precise. The Nes formula performs best for people aged 25–60. All three give similar results; the difference is typically ±2–5 bpm.
Is the anaerobic zone good for weight loss?
Yes — training in the anaerobic zone burns more calories per minute than lower-intensity exercise. It also increases resting metabolic rate for hours after the session (the "afterburn" or EPOC effect). However, do not train exclusively in the anaerobic zone, as adequate aerobic base training is essential for long-term progress and recovery.
How is this different from VO₂ Max training?
The anaerobic zone (80–90% of max HR) sits just below the VO₂ max zone (90–100%). VO₂ max training is more intense and can only be sustained for short bursts, while anaerobic training can be sustained for several minutes. Both are important for peak athletic performance.