How is the Anaerobic Threshold determined?
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The determination of the anaerobic threshold is practiced by two different methodical approaches - invasive and non-invasive.

Invasive Anaerobic Threshold determination is based on the lactate measurement. Either the catheter is inserted into one of the brachial arteries or the collection of blood from an ear (auricle) or a finger is applied. The lactate shows an exponential increase (or decrease in the case of basis surplus) together with growing acidosis [1].

Non-invasive methods use the spiroergometric values for the Anaerobic Threshold determination. They were developed by Wasserman [2] and are based on the principle that the respiration reflects the internal physiological response on exercise and that the lactate production has disturbing effects on breathing. Therefore it is possible to use the effects of lactate production on gas exchange to identify non-invasively the exercise at which arterial lactate starts to increase.

What agreement exists between the Anaerobic Threshold determined invasive and non-invasive is disputable. Some authors found between these values agreement [3],[4] but others prove that no relationship is between increasing amount of lactate and the change of ventilation [5][6]. The second attitude rises the question what Anaerobic Threshold should be used for the practice if does not exist the agreement between anaerobic thresholds. The lactate testing is common in the countries with higher GDP; nevertheless the rest of the word mainly uses the cheaper spiroergometric examination. However, not only economic reasons testify against the lactate testing.

Some research works on lactate has contributed to the physiological reasons against of it, e.g. it was showed that patients suffering from McArdle's Syndrome (a genetic disorder in which victims lack the enzyme phosphorylase, which renders them incapable of catabolising glycogen and forming lactic acid - they are not able to mange the synthesis of muscle lactate) have break in ventilation response on load in unchangeable form and thus the Anaerobic Threshold is independent of amount of lactate arisen in muscles [8]. Furthermore; the invasive validations of Anaerobic Threshold have been based on lactate data of arterial, mixed venous, venous, and capillary blood samples without any concern for the possible lactate differences from these sources making the invasive Anaerobic Threshold assessment problematic [9]. The current lactate research was summarised by Brooks [10] who states that the concentration of lactate in the blood provides minimal information about the rate of lactate production in muscle and the lactate increase is only a form of the acute blood redistribution after the lever anaemia. Therefore the ventilation response is not the compensation mechanism but the control mechanism occurring at the same time.

Despite of many different views of the Anaerobic Threshold determination, this parameter has become important not only in research but also in clinical practice, where serves for the review of the cardiorespiratory system and also for the appreciation of the physical fitness. Nowadays the Anaerobic Threshold expressed in heart rate or workload intensity is treated in medicine as one of standard physical fitness criterion. Moreover the dosing of sportsmen workload with respect to its Anaerobic Threshold affects the improving of oxygen transport capacity together with the increase of cardiac output[11], the increase of myoglobin capacity in muscles, the increase of perfusion in muscles etc. .

References:

[1] Gladden, L.B. Lactate transport and exchange during exercise. In: Handbook of Physiology, Section 12, Exercise: Regulation and Integration of Multiple Systems. L.B. Rowell, and J.T. Shepherd (Eds). New York:Oxford University Press 1996. [2] Wasserman, K.W., J.E. Hansen, D.Y. Sue, B.J. Whipp: Principles of Exercise Testing and Interpretation. Philadelphia: Lea&Febigner, 1987 [3] Aigner A, Muss N. Wertigkeit einer nicht-invasiven Methode zur Bestimumg der anaeroben Schweller unter Laborbedingungen und im Feldtest. Dtsch Z Sportmed 1983;34;284-289. [4] Yoshida, T., Chida, M., Ichioka, M. & Suda, Y. (1987). Blood lactate parameters related to aerobic capacity and endurance performance. European Journal of Applied Physiology, 56, 7 - 11. [5] Gaesser, G.A. & Poole, D.C. (1986). Lactate and ventilatory thresholds: disparity in time course of adaptations to training. Journal of Applied Physiology, 61(3), 999 - 1004. [6] Aunola S, Rusko H. Reproducibility of aerobic and anaerobic thresholds in 20 - 50 year old men. Eur J Appl Physiol 1984;53; 260-266. [7] Gladden, L.B. Lactate transport and exchange during exercise. In: Handbook of Physiology, Section 12, Exercise: Regulation and Integration of Multiple Systems. L.B. Rowell, and J.T. Shepherd (Eds). New York:Oxford University Press 1996. [8] Hagberg J M. Ventilatory threshold without increasing blood lactic acid levels in Mc'Ardle disease patients. Med Sci Sports Exerc 1981;13:115-8. [9] Yeh MP, Gardner RM., Adams TD, Yanowitz FG, Crapo RO. ”Anaerobic threshold”: problems of determination and validation. J App Physiol 1983;55(4);1178-1186. [10] Brooks, G.A. Current concepts in lactate exchange. Medicine Science for Sports and Exercise. 23: 895-906, 1991 [11] Vago P, Mercier J, Ramontaxo M et al. Is ventilatory anaerobic threshold a good index of endurance capacity? Int. J. Sports med.1987;8:190-5
 
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