The lactate test is used to determine the anaerobic threshold.If too much lactate is formed, it means that the muscles of the body do not have enough oxygen available for energy production (= anaerobic threshold). Instead, more glucose is broken down, creating lactate. To dispose of the lactate again, it must be metabolized into carbon dioxide and water. This leads to an increase in lactate levels, because the breakdown of lactic acid takes longer than its formation.A distinction is made between training in the aerobic zone, where sufficient oxygen is available, and training in the anaerobic zone, where glucose is already broken down to a greater extent and thus larger amounts of lactate are formed. This lactate production of the cells can be used in lactate performance diagnostics in sports. Here, the individual physical performance can be determined by repeatedly determining the lactate value as part of a step test.
The procedure
In the lactate test, the load intensity on a treadmill or bicycle ergometer is increased in several steps.
At the end of each load step, a small drop of blood is taken from the finger or earlobe and the current lactate concentration of the blood is determined. At the same time, the heart rate is recorded during the test.
If the lactate concentration in the blood reaches approximately 4 mmol/l, the anaerobic threshold is reached at the indicated heart rate.
If too much lactate is formed, this means that the body’s muscles – due to too intense a load when the anaerobic threshold is exceeded – do not have enough oxygen available for energy production. However, the efficiency of energy production per molecule of glucose drops to 1/19th without cellular respiration. Now, a disproportionate amount of glucose is degraded by glycolysis to continue to meet the energy demand, consuming the coenzyme NAD+ needed there to form NADH/H+ – without typically being regenerated in cellular respiration. For the required regeneration of NADH/H+ to NAD+, the accumulating end product of glycolysis (pyruvate) is now reduced to lactate. Lactate can only be metabolized when the organism has returned to aerobic respiration.
Lactate measurement results are assessed as follows:
| Measured value | Interpretation |
| up to 2 mmol/l | aerobic |
| up to 4 mmol/l | Limit range |
| > 4 mmol/l | anaerobic |
The lactate test is necessary for
- Determination of the optimal training heart rate
- Assessment of the current quality of training
- Conduction documentation (comparison of power output (watts) in relation to lactate and heart rate values).
Note!Optimal is to perform the lactate test in an individual environment of the competitive athlete (eg, racing bike, running track, rowing boat, etc).Alternatives are treadmills or rowing ergometers.
Benefits
The lactate test is used to determine the optimal training range – up to the anaerobic threshold – and thus prevent overloading of the body and muscles.Only in this way can optimal performance in training be achieved.
