Anaerobic Threshold (AnT)

You can think of Anaerobic Threshold (AnT) as the transition between a pace or power you can hold steadily and an intensity where fatigue starts accumulating much faster. Many training systems use it as a reference for threshold training, and it is often discussed alongside FTP, LTHR, and threshold pace.

Key characteristics

• Limited duration: for many athletes it sits near the best steady effort you can sustain for tens of minutes up to ~1 hour (varies by sport and athlete).
• High cost above the line: above AnT, holding the same intensity gets harder quickly.
• Lab definitions vary: some use gas exchange breakpoints; others use blood lactate. Different definitions can yield different numbers—this is normal.

Practical estimation

If you don’t have lab testing, use repeatable field tests to approximate it:

• 20-minute steady test (common approach):
  • Do a maximal, as-steady-as-possible 20-minute effort.
  • Use the 20-minute average power/pace (or HR) as a reference, and apply a practical adjustment factor.
  • This aligns with common FTP estimation practice.

Training relevance

Raising AnT often means you can sustain a higher steady pace or power before fatigue rises sharply. But it is not the only driver of performance: economy, durability, fueling, and pacing matter too.

How Trainingload.ai uses anaerobic threshold

• Threshold context: AnT helps explain why FTP, LTHR, and threshold pace all point toward a similar training intensity range.
• Workout classification: threshold sessions can be reviewed against pace/power, heart rate, RPE, and recent fatigue.
• Zone calibration: when a reliable threshold estimate exists, it can improve pace, power, and heart-rate zone boundaries.

Related tools and docs

• Lactate Threshold
• Functional Threshold Power
• Calculate heart-rate training load zones
• Calculate power training load zones

References

• Joe Friel: Common But Confusing Training Terms