The anaerobic threshold (AnT) is defined as the highest sustained intensity of exercise for
which measurement of oxygen uptake can account for the entire energy requirement. At the
AnT, the rate at which lactate appears in the blood will be equal to the rate of its disappearance.
Although inadequate oxygen delivery may facilitate lactic acid production, there is no
evidence that lactic acid production above the AnT results from inadequate oxygen delivery.
There are many reasons for trying to quantify this intensity of exercise, including assessment
of cardiovascular or pulmonary health, evaluation of training programs, and categorization
of the intensity of exercise as mild, moderate, or intense. Several tests have
been developed to determine the intensity of exercise associated with AnT: maximal lactate
steady state, lactate minimum test, lactate threshold, OBLA, individual anaerobic threshold,
and ventilatory threshold. Each approach permits an estimate of the intensity of exercise
associated with AnT, but also has consistent and predictable error depending on protocol
and the criteria used to identify the appropriate intensity of exercise.
The authors are with the Human Performance Laboratory, Faculty of Kinesiology,
University of Calgary
Few concepts in the field of exercise science have generated such debate as that of
Disagreement among researchers stems not only from the
absence of methodological standardization but also from a lack of consensus on
the theoretical basis of the concept itself.
Efforts to accurately describe a threshold
intensity have resulted in an immense pool of scientific data. Yet the issue remains
an unresolved controversy.
One reason for the ongoing controversy is the lack of
consensus for the definition of anaerobic threshold and the persistent inappropriate
use of the term.
It is important to recognize that anaerobic threshold is a concept,
and that the definition is a conceptual definition. In contrast, the various
ways to detect the intensity of exercise associated with the anaerobic threshold
have resulted in a proliferation of terms that are more appropriately given operational
definitions. These measurements should not always be equated with anaerobic
threshold, since there are clear differences between conceptual and operational
definitions. Considering the inconsistency with which these terms are used, readers
should interpret a term like anaerobic threshold or lactate threshold from the
context of its use.