Knowledge Base > Physiology and Metrics

Anaerobic Threshold

The anaerobic threshold (AT) describes your endurance performance. It is defined as the maximum power at which lactate production (glycolytic system) and lactate degradation (aerobic system) are still in balance.

Lactate degradation (aerobic metabolism) increases linearly with increasing power, as does oxygen uptake. Lactate production (glycolytic metabolism), on the other hand, increases exponentially with increasing power. The intersection of the two curves marks the equilibrium of lactate production and degradation, i.e. the anaerobic threshold. The anaerobic threshold describes a performance that can be maintained over a longer period of time. As a rule, the performance at the anaerobic threshold can be maintained for about 40-70 minutes until other factors limit the performance.

The power at the anaerobic threshold is given absolutely or relative to the body weight. For a 75kg athlete with an absolute anaerobic threshold of 300 watts, the relative anaerobic threshold is 4 watts/kilogram

Note In practice, the anaerobic threshold is not a fixed point, but rather describes a performance range of about 10 watts, which can also shift depending on fatigue, carbohydrate availability, altitude and climatic conditions. To target this range in training, to use it as a basis for a pacing strategy, or to track performance development, it is advisable to examine the anaerobic threshold regularly throughout the season and to perform appropriate performance diagnostics.

Why should I know my anaerobic threshold?

The anaerobic threshold describes your maximum long-term power output and is therefore a very good indicator of performance in endurance sports. Although there are only a few competitions and situations in which you are permanently at your AT (e.g. a steady time trial for about 45min). Most of the time, your power output is either above your anaerobic threshold (race-deciding situation in a bike race) or below it (steady pacing in a triathlon long distance). However, your anaerobic threshold will largely determine the relative race performance you will have in your next bike marathon or triathlon.

Knowing how your anaerobic threshold is composed and the power level at which it is located is a basic requirement to effectively control and plan your training.

What is the difference to the FTP?

FTP (Functional Threshold Power) is an arbitrary metric that has no physiological basis. The classic method for determining your FTP, a 20min test, almost always overestimates your 60min performance. In addition, your FTP gives you no information about how your power is composed. Functional threshold power and anaerobic threshold both describe a continuous power output, but on their own they only show the pure power output. To improve your anaerobic threshold and effectively manage your training, you need to understand how this power is composed. By differentiating between aerobic and anaerobic metabolism, AI DIAGNOSTICS helps you better understand your endurance performance and train more effectively.