The anaerobic threshold: 50+ years of controversy.
J Physiol
; 599(3): 737-767, 2021 02.
Article
em En
| MEDLINE
| ID: mdl-33112439
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 ( VÌCO2 ). Its principal tenets were limiting oxygen (O2 ) delivery to exercising muscleâincreased glycolysis, La- and H+ productionâdecreased muscle and blood pHâwith increased H+ buffered by blood [HCO3- ]âincreased CO2 release from bloodâincreased VÌCO2 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 ( VÌO2 ) 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 VÌCO2 versus VÌO2 ) remains important in exercise training and in the clinic, but its conceptual basis should now be understood in light of lactate shuttle biology.
Palavras-chave
CPET; cardiopulmonary exercise test; critical power; critical speed; dysoxia; exercise; gas exchange; gas exchange threshold; gluconeogenesis; glycolysis; hypoxia; isocapnic buffering; lactate; lactate appearance; lactate clearance; lactate disposal; lactate oxidation; lactate signalling; lactate threshold; lactic acid; maximal lactate steady state; oxygen; ventilatory threshold
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Base de dados:
MEDLINE
Assunto principal:
Limiar Anaeróbio
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Teste de Esforço
Idioma:
En
Revista:
J Physiol
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Estados Unidos