Lactate determination
The principle for the determination of lactate levels in blood is based on the photometric determination of a dye which is produced by adding two enzymes. More precisely, these are the two enzymes lactate oxidase (“LOD”) and peroxidase (“POD”). First the lactate present in the blood reacts with the lactate oxidase to form pyruvate and H2O2.
In the next reaction step, after the addition of 2 substances (4-amino-phenazone and 4-chlorophenol) with the help of the peroxidase, the dye quinonimine is formed. This can be measured at 520 nm with a photometer, so that it is possible to draw conclusions about the lactate values present in the capillary blood of the earlobe. It is important that the reagent contains a glycolysis inhibitor in addition to the blood, enzymes and substances. This prevents the glucose contained in the reagent from being converted into lactate during the measurement, which would lead to false high lactate values. Since the two enzymes give the enzyme its name, this principle of lactate value determination is also called the LOD-POP method.
Importance of performance diagnostics in sports
Nowadays it is common to determine the individual lactate threshold in order to recognize and optimize your personal performance limits. Training in the range of the lactate threshold described above is particularly effective for endurance performance and a resulting increase in performance has been proven in several studies. The higher the threshold, the greater the lactate tolerance of the physical organism to the salts of lactic acid.
This means that the personal lactate threshold describes the ability of the person to tolerate certain lactate levels and to maintain the level of stress. The lactate threshold can be increased through targeted training. A higher threshold would, for example, make it possible to run a marathon in a better time.
This so-called shift of the lactate threshold cannot be achieved with a general training plan, but only with individually adapted exercises after appropriate analysis of the lactate values depending on other factors. An important factor that plays a role in this is the heart rate.With increasing speed, the heart rate also increases. This increases linearly compared to the lactate value; the lactate value, on the other hand, increases exponentially.
As soon as the lactate threshold is exceeded, there is a sudden increase. In lactate performance diagnostics, lactate is usually determined by means of a multi-step test. This serves to determine your own lactate values more precisely in connection with your heart rate, i.e. certain pulse values.
The indication of the lactate thresholds with 4mmol/l is only a generalized value, which can vary between 1mmol/l more or less. The multi-step test can therefore be used to determine the “IANS”, i.e. the individual anaerobic threshold. To perform the test, the person in question runs either in the open air or on a treadmill.
The speed or intensity is gradually increased in fixed steps (? therefore multi-step test). After each increase, the individual performance is determined by measuring the lactate level in the capillary blood of the earlobe.
With the help of a specialized computer program, the values can be analyzed and displayed in a lactate curve. The lactate curve shows the lactate concentration as well as the pulse values at the respective time. This allows an objective evaluation of the load limits; especially with regard to the increase in performance in the form of a shift in the lactate threshold.
