Methodological approach to the first and second lactate threshold in incremental cardiopulmonary exercise testing

Abstract

Determination of an 'anaerobic threshold' plays an important role in the appreciation of an incremental cardiopulmonary exercise test and describes prominent changes of blood lactate accumulation with increasing workload. Two lactate thresholds are discerned during cardiopulmonary exercise testing and used for physical fitness estimation or training prescription. A multitude of different terms are, however, found in the literature describing the two thresholds. Furthermore, the term 'anaerobic threshold' is synonymously used for both, the 'first' and the 'second' lactate threshold, bearing a great potential of confusion. The aim of this review is therefore to order terms, present threshold concepts, and describe methods for lactate threshold determination using a three-phase model with reference to the historical and physiological background to facilitate the practical application of the term 'anaerobic threshold'.

What we may learn from lactate time curves by means of piecewise polynomial regression methods.

“…However, we must take into consideration that routine data were retrospectively evaluated, to show the appropriateness of this new curve fitting approach. the deflections points which could be estimated using lactate or heart rate versus workload curves probably reflect the transition between phase I and phase II of the three-phase lactate model (3). Interestingly, the heart rate ("conconi approach of aerobic threshold") fits best with the theoretical lactate break point at 2 mmol/l.…”

“…Different approaches have been used to determine break points (turn points, deflection points, transition points) of lactate versus workload curves, which have been improved by log-log transformation of the data (3,19). A summary of various technical, mostly graphical methods, to stipulate turn points including references can be found under https://de.wikipedia.org/wiki/Anaerobe_schwelle .…”

“…However, this concept has also been subject of scientific discussion and investigators have to spend much effort for the test (13). In addition, the 15-point (6 to 20) Borg rating of perceived exertion (Bs) has gained more interest to measure exercise intensity (3,7). the Borg scale or rPE (rating of Perceived Exertion) corresponds to the subjective perception during physical activity.…”

“…Lactate workload curves remain the principle investigation to assess and guide exercise intensity in athletes (1,2,3,4,5,6). Moreover, heart rate and subjective perceived exertion (Borg scale) are associated with exercise intensity and may give us basic information about physical performance of subjects (7).…”

“…Interpretation of lactate versus workload curves has unfortunately not been internationally standardized, therefore the definitions given by Binder et al (3) will be applied in this paper. Briefly, 3 phases (very light exercise, light to moderate exercise and heavy exercise) are separated by two thresholds (tH): 1st lactate threshold (transition of phase I to phase II) corresponding to the "aerobic" tH (Lac ~2 mmol/l) and 2nd lactate threshold (transition between phase II and phase III) corresponding to the "anaerobic" tH (lac ~4 mmol/l).…”