Does Anaerobic Threshold Really Exist?

Would you consider yourself a serious endurance athlete?

If you answered yes, it’s likely you’ve heard of some, or all of these terms:

The term Anaerobic Threshold (AT) is perhaps one of the most confusing terms in endurance sports training. The primary reason for using measurements to infer AT is because it is more of a ‘concept’ than an established metric.

The term anaerobic is often used erroneously to denote exercise that occurs ‘without oxygen.’ Exercise that uses oxygen is referred to as ‘aerobic.’ Therefore, the common thought process regarding aerobic and anaerobic exercise is that once an individual reaches their AT, their body “switches” from using oxygen (aerobic) to the anaerobic energy systems to provide energy.

This is incorrect. In actuality, oxygen is present at all times during intense exercise. Anaerobic energy systems supplement the aerobic system to meet the increased energy demands.

Is AT Real

The term, Anaerobic Threshold was created by Wasserman and McIlroy in 1964 as a way to identify a safe, sub-maximal intensity for cardiac patients to exercise at. The premise of their Anaerobic Threshold Theory was that blood lactate accumulation was the result of poor oxygen levels – NOT that an individual had switched over from using oxygen to using anaerobic energy systems to provide energy.

So is AT real? Depends. It all comes down to how you define it. However, for all intents and purposes, it is advised that one’s lactate threshold (LT) is a better metric than AT, primarily because it can be quantitatively measured and therefore it is not a concept but an actual metric. Remember, you are not inferring that LT is the same as AT – they are two different things.

Rick Prince is the founder of United Endurance Sports Coaching Academy (UESCA), a science/evidence-based endurance sports coaching education company that certifies running and triathlon coaches.

To get a $50 discount on the Running Coach Certification, click here!


Svedahl K, MacIntosh BR. Anaerobic threshold: The concept and methods of measurement” 2003. Apr: 28(2): 299-323
Wasserman K, M.B. McIlroy (1964). “Detecting the Threshold of Anaerobic Metabolism in Cardiac Patients During Exercise”. Am. J Cardiol. 14: 844-852
Ohira Y, Tabata I. Muscle metabolism during exercise: anaerobic threshold does not exist”. Ann Physiol Anthropol. 1992: May 11(30): 319-23.

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