The anaerobic threshold: 50+ years of controversy

Abstract

The anaerobic threshold (AT) remains a widely recognized, and contentious, concept in exercise physiology and medicine. As conceived by Karlman Wasserman, the AT coalesced the increase of blood lactate concentration ([La−]), during a progressive exercise test, with an excess pulmonary carbon dioxide output (V̇normalCO2). Its principal tenets were: limiting oxygen (O2) delivery to exercising muscle→increased glycolysis, La− and H+ production→decreased muscle and blood pH→with increased H+ buffered by blood [HCO3−]→increased CO2 release from blood→increased V̇normalCO2 and pulmonary ventilation. This schema stimulated scientific scrutiny which challenged the fundamental premise that muscle anoxia was requisite for increased muscle and blood [La−]. It is now recognized that insufficient O2 is not the primary basis for lactataemia. Increased production and utilization of La− represent the response to increased glycolytic flux elicited by increasing work rate, and determine the oxygen uptake (V̇normalO2) at which La− accumulates in the arterial blood (the lactate threshold; LT). However, the threshold for a sustained non‐oxidative contribution to exercise energetics is the critical power, which occurs at a metabolic rate often far above the LT and separates heavy from very heavy/severe‐intensity exercise. Lactate is now appreciated as a crucial energy source, major gluconeogenic precursor and signalling molecule but there is no ipso facto evidence for muscle dysoxia or anoxia. Non‐invasive estimation of LT using the gas exchange threshold (non‐linear increase of V̇normalCO2 versus V̇normalO2) remains important in exercise training and in the clinic, but its conceptual basis should now be understood in light of lactate shuttle biology.

Can an Incremental Step Test Be Used for Maximal Lactate Steady State Determination in Swimming? Clues for Practice

“…It has been considered as the initial rise in BLC above rest, the onset of a fixed blood lactate accumulation ranging from 2.0 to 4.0 mmol L −1 , or with curve fitting procedures [ 7 ]. These methods seem to be correlated, but their relationship with the boundaries that separate the intensity domains are affected by the methodology chosen, without a clear physiological support for the preference of one of them [ 8 ].…”

Contributions by the Cologne group to the development of lactate exercise testing and anaerobic threshold concepts in the 1970s and 1980s

“…I have enjoyed reading the excellent review on the anaerobic threshold celebrating the abundant work arising from the premise originally put forward by Prof Karlman Wasserman (Poole et al . 2021). However, the review has regrettably missed some important contributions published in German by the sports medicine group in Cologne.…”

Reply from David Poole, Harry Rossiter, George Brooks and L. Bruce Gladden

“…Poole et al . 2021); and (3) whereas training adaptations based upon [La − ] may have considerable utility, it is notable that, at least for non‐elite athletes, training outcomes (LT and ) are not necessarily dependent upon training at a certain [La − ] (Poole & Gaesser, 1985).…”