When you train, your body needs energy. At moderate effort it gains this energy mainly aerobically, that is, with sufficient oxygen. The more intensely you train, however, the faster the body has to provide energy – and in doing so lactate is produced.
Lactate is not a waste product, as is often assumed, but a valuable energy carrier that the body continuously keeps processing further. As long as production and breakdown are in balance, you can hold a high intensity well.
This is exactly where the anaerobic threshold comes into play: it marks that point at which your body still breaks down just as much lactate as it produces – that is, an output you can hold steady for about 20 minutes, without the lactate level in your blood rising significantly. In this so-called steady-state, lactate does form through the energy supply, but your body can reuse it at the same time, for example in organs such as the heart and even the brain. However, if the effort rises beyond this point, the balance tips: metabolic products accumulate faster, the muscles begin to burn and fatigue sets in noticeably earlier.
In short:
The anaerobic threshold is the highest effort intensity you can hold steady over a longer period without lactate accumulating excessively.
The anaerobic threshold is therefore the point at which:
- your body can still break down just as much lactate as it produces
- the muscles are indeed challenged, but still work stably
- you can hold the intensity for a long time without “over-acidifying”
It is one of the most important markers of your endurance performance.
Why is the anaerobic threshold so important?
It shows you:
- how long you can sustain high intensities
- how well your body processes energy
- how efficiently your cardiovascular system works
The higher your anaerobic threshold, the:
- faster you can run, cycle or train
- later your muscles fatigue
- more stable you are during demanding workouts
For many sports – from the fitness center to team sports through to endurance training – the threshold is a very decisive performance indicator.
What happens in the body at the anaerobic threshold?
At the anaerobic threshold, two systems work simultaneously:
- Aerobic energy production – energy from oxygen, efficient, lasting
- Anaerobic energy production – fast energy without oxygen, produces lactate and other metabolic products
As long as these two systems are in balance, the lactate level also stays stable – you can sustain the intensity.
If you exceed the threshold, the following happens:
- lactate rises quickly
- muscles “burn”
- breathing becomes harder
- performance drops off faster
That is why the anaerobic threshold is a precise effort marker.
What is important here – as mentioned above – is that it is not the lactate itself that is the problem. Lactate is not a waste substance; it even helps your body continue to provide energy.
The actual “burning” is thought to be caused by hydrogen ions (H⁺), which build up in greater amounts under high effort. They make the musculature more acidic, which leads to this well-known sensation and to faster fatigue.
Lactate forms in parallel with these processes and is not the cause of the over-acidification. But because lactate is easy to measure and is closely linked to the rise in H⁺ ions, it is used in performance diagnostics as a practical marker for what is happening in the muscle – for example when determining the anaerobic threshold.
Although the typical burning around the anaerobic threshold arises mainly from the rise in H⁺ ions, changes in calcium balance or the decline of creatine phosphate stores also contribute to fatigue.
How do you measure the anaerobic threshold? – explained clearly
There are three common methods. Here they are briefly and clearly:
Lactate step test – the standard test
The lactate step test is the most classic and reliable method. The effort increases in steps (e.g. +30 watts when cycling or +2 km/h when running). Each step lasts 2–3 minutes. After each step a little blood is taken from the earlobe or finger to measure the lactate value, and the heart rate is recorded.
Good to know: The test can be carried out on a bike, rowing or arm ergometer, on the treadmill or even in a swimming flume. For teams, field tests on the 400 m track are also suitable.
You recognize the anaerobic threshold by the fact that the lactate value rises exponentially from a certain point onward.
Advantage: Very accurate Disadvantage: requires specialists or a test lab
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Spiroergometry – the breathing analysis
During spiroergometry you wear a breathing mask that measures oxygen uptake and CO₂ output, with the effort likewise increasing in steps or continuously.
Besides many other parameters, it primarily measures your aerobic and anaerobic threshold, the VO₂max (maximum oxygen uptake) as well as the share of carbohydrate and fat utilization – giving you a very precise insight into your metabolism and performance capacity.
Advantage: medically very precise Disadvantage: higher costs, only in specialized centers
3. Conconi test – simple alternative for fitness centers & amateur sport
The Conconi test measures the heart rate together with the increasing speed or – depending on the device – the wattage. The intensity increases step by step (e.g. every 200 m on the running track). The anaerobic threshold is estimated via a so-called deflection point (flattening of the heart rate curve despite increasing effort) in the heart rate progression.
Advantage: inexpensive, good for groups Disadvantage: less accurate and not evaluable in all people
How do you train sensibly around the anaerobic threshold? – practical examples
The anaerobic threshold is a central point of orientation for training control. Depending on intensity and duration, the following three methods train different parts of your endurance.
Especially important: not only the threshold zone itself, but all three zones contribute to a complete endurance performance – each in its own way.
A) Training below the threshold
Goal: base endurance & a more efficient energy metabolism (improvement of fat metabolism)
This is the zone in which you lay the foundation of your endurance. Here you strengthen your cardiovascular system, improve oxygen uptake and promote fat metabolism.
Intensity:
- 65–75 % HRmax
- Borg 3–5
Typical:
- 20–45 min of moderate running, cycling or walking
- calm cardio sessions (bike, cross trainer, rowing machine)
Why is it important? Even though this zone does not directly raise the anaerobic threshold, it builds the foundation you need to be able to deliver high performance in the threshold zone at all.
B) Training at the threshold
Goal: raise the threshold & improve lactate utilization ➡️ This zone trains the anaerobic threshold most strongly.
Here you work very close to the so-called maximal lactate steady-state. It is precisely in this zone that your body learns to handle higher amounts of lactate efficiently and to sustain the effort longer.
Intensity:
- 85–90 % HRmax
- Borg 7–8
Typical:
- tempo runs 10–40 min
- intervals such as 2-6×8-16 min
- evenly hard sessions on the bike or rowing machine
Why is it important? If you specifically want to raise your anaerobic threshold, this is exactly the zone that brings the strongest effect.
C) Training above the threshold
Goal: maximum performance, VO₂max (maximum oxygen uptake), anaerobic capacity & lactate tolerance
Here the effort becomes so high that lactate rises quickly and fatigue increases sharply.
Intensity:
- >90 % HRmax
- Borg 8–9
Typical:
- 15–240 second intense intervals with 2-3 minutes of rest
- HIIT sprints or explosive elements with short pauses in between
Why is it important? Although this zone does not primarily improve the anaerobic threshold, it boosts your maximum performance, your speed and your lactate tolerance – abilities that in turn help to train the threshold zone more effectively and to withstand more intense sessions better.
Why the anaerobic threshold is important for everyone – not just for pros
A higher anaerobic threshold leads to:
- noticeably better endurance in everyday life
- less rapid fatigue
- more efficient training
- better cardiovascular function
Even gym members benefit enormously: workouts feel more controlled and easier, even though you become stronger.
Conclusion: the anaerobic threshold is a central marker for intelligent training
The anaerobic threshold shows how long you can hold intense efforts – and is thus one of the most important parameters in training control. With a clear measurement and suitable training zones you can make your training more efficient and improve your performance in a targeted way.
Whether everyday life, health or sport: those who know their anaerobic threshold can classify training and effort more precisely and steer them sensibly and individually.
