Anaerobic Thresholds - Definitions
What is the anaerobic threshold?
The anaerobic threshold is a term coined in 1964 by Karl Wasserman when he used VO2 measurements to show a change in the gas curve that seemed to correspond with an increase in lactate in the blood. At a point on the curve, CO2 increased more than he expected. The subjects were producing more lactate than the muscles could consume; the buffering of this lactate was thought to cause the observed increase in CO2. Wasserman called this the anaerobic threshold because it was thought that the body was suddenly transitioning to anaerobic metabolism.
Some other researchers later pointed out that while excess lactate was being produced and it appeared in the blood stream, the body was in a steady state. Oxygen was still being used in ever greater amounts. So while the lactate in the blood indicated a somewhat greater involvement of the anaerobic system, and CO2 increased confirming this, aerobic metabolism was still the main source of energy, was still increasing and was not near maximum. Thus, there was no change to anaerobic metabolism at this point and no reason to use the term "threshold."
It should be noted that the term anaerobic threshold has in recent years has been re-defined to mean a much higher effort level: the maximum level that an athlete can maintain for a long time without causing lactate to rise sharply.) See popup on the lactate threshold? This lactate level is called the maximal lactate steady state.
More on Wasserman's study. Here are two quotes from the original Wasserman study:
He then went on and used the specific term, "anaerobic threshold" because he believed that this was where the anaerobic system took over. He was wrong about this and that is what science is about. Discoveries like Wasserman's are what move the ball along but unfortunately his idea of a major abrupt change in anaerobic metabolism was wrong. This misconception persists till today with many people. Anaerobic metabolism occurs before this so-called threshold point, and aerobic metabolism continues after it. And the place on the gas curve he pointed out is not an important point for training for endurance sports.
Wasserman was not the first to find this point: Hollmann had published the same information in 1959, but Hollmann’s work was in German and not known in most of the world at that time. Both Hollmann and Wasserman are still alive. Hollmann was head of the German Sports Academy where Alois Mader worked and Jan Olbrecht got his degree. And who are these people? They figured out how the body mixes aerobic and anaerobic metabolism and how to use this information to train athletes. There is more information about them and their discoveries on this website. We also have a more detailed discussion on this topic on our thresholds page especially on how to train the thresholds.
In reality the terms lactate threshold and anaerobic threshold are used interchangeably by most coaches. And the meaning they have is that of the maximal lactate steady state.
There is one major exception. Namely, many researchers and coaches will use the
term anaerobic threshold to mean the effort level that produces 4 mmol/l of lactate and is often
referred to as the V4. Originally this was thought to be the upper level of steady state lactate in the
blood but it was quickly learned that many athletes had higher lactate levels at the maximal lactate
steady state and most endurance athletes had lower lactate levels at the maximal lactate steady state.
The V4 term is still very popular and we use is frequently because it is an easy level to measure and
correlates with the maximal lactate steady state.