Synonyms in the broadest sense
Lactic acid, salt of lactic acid, hydroxy acid, lactate concentrationLactate is the resulting end product of the anaerobic oxidative (using oxygen) metabolism. This leads to an oxidation of the grape sugar (glucose). This form of energy supply occurs in sports training when the energy requirement is greater than the energy supply, and mostly occurs in the striated muscles.
This anaerobic, lactacidic energy deficit occurs particularly at the beginning of athletic stress and during longer sprint loads in speed training (400m, 800m). Therefore these forms of stress are considered very unpleasant. While the lactate level in the blood rises, the concentration of H+ ions increases, which leads to acidosis.
Lactate in blood
Lactate is mainly and in large quantities released from muscle cells during sporting activities. However, it can also enter the bloodstream by other means, such as in the case of oxygen deficiency or infection. Lactate is no longer broken down directly in the muscle, but in other organs (liver, kidney, heart).
The lactate level that can be determined in the blood is the result of a constant new formation and the continuous breakdown of lactate. This blood lactate level depends on the degree of physical exertion, but also on the training condition as well as on the diet, alcohol consumption, certain medications (e.g. metformin for diabetes mellitus) or general illnesses associated with a reduced oxygen supply, where the purely aerobic metabolism is no longer possible after a short time. Almost every pathological condition, due to which the amount of oxygen required in the tissue is too low, the lactate production is too high or the lactate breakdown is too low, consequently leads to an increased production of lactic acid salt.
In most cases, a combination of all these factors can be assumed. If too much lactate accumulates in the blood, this is initially referred to as hyperlactatemia, which is characterized by a slight excess of the normal value and in which it is still possible to compensate for the state of hyperacidity (for example, by increased breathing). If the level continues to rise in the following, lactate acidosis ultimately occurs, which is accompanied by a sharp drop in blood pH (normal blood pH = 7.4) and such a sharp increase in lactate concentration that the organism’s compensation mechanisms are no longer adequate.
In addition, elevated values can also occur during or shortly after an operative intervention as well as in patients in a state of shock (circulatory failure of various genesis). Therefore, lactate diagnostics is a standard procedure of every medical laboratory and, in addition to its usefulness in monitoring the training condition of an athlete, it is also extremely relevant for the diagnosis and prognostic assessment of shock patients and much more. Due to the constant build-up and breakdown of lactate, the body normally establishes a balance up to a certain stress intensity: Simultaneous lactate formation and utilization creates a state in which no net lactate production is to be expected.
This is known as a steady state. This term is mainly used in chemistry and also in biochemistry and only describes the fact that the formation and decomposition of certain substances in the body are not individual isolated processes, but a “flow” can be observed. Individual reactions are interdependent and adapted to each other to the most precise degree.
Lactate is produced, passes into the bloodstream and is rapidly broken down from there. If more lactate is produced, the blood lactate level rises slightly at first, while more lactate is then broken down again. Many other reactions and metabolic pathways of the body also work according to this principle.
The Lactate Steady State is of great importance for sports medical examinations or individual performance measurement and control, which is possible via the lactate level. For example, in the usual stress tests (e.g. on a bicycle ergometer), the physical stress of the patient/test person is gradually increased after a certain time. In the case of the bicycle ergometer, this load can be regulated via the resistance.
As a result, the lactate level in the blood rises measurably because the muscles need more energy to perform the increased work. A relatively high lactate level can therefore be determined for a short period of time.After some time, a new equilibrium (= new steady state) is reached for exactly this load level. The lactate levels in the blood of the test person would now no longer change.
This principle is used until there is no more steady state, because the body can no longer compensate for the significantly increased load. It comes to a continuous lactate rise, which causes in the long run also the entering exhaustion condition and lets the test person terminate the test. Such a lactate level test is very common, especially for top athletes and endurance athletes at competition level for training optimization.
It is classically used for marathon and half-marathon runners, triathletes and cyclists. The concentration of lactate at rest is about 1mmol/liter. The lactate concentration is measured in the blood, usually at the earlobe.
During slow sporting activities, the lactate level is about 2mmol/liter. This is called an aerobic threshold. In this phase, the lactate produced is sufficiently eliminated.
If the value of the lactate produced corresponds to that of lactate elimination, it is called a lactate steady-state. This is also called aerobic- anaerobic transition at about 2-4 mmol/liter andc. The anaerobic threshold lies at approx.
4 mmol/liter. If this value occurs during sports activities, the metabolism is called anaerobic (without consumption of oxygen). Lactate values of up to 25mmol/litre have been measured in top athletes. The pH value was about 7 in the blood (normally 7.4).