Pulse, blood pressure and lactate measurement: to test the endurance and resilience of the cardiovascular function, easy to determine parameters such as pulse rate, respiration and blood pressure are suitable. As the oxygen demand in the muscles increases during exercise, the respiratory rate, the heart beat volume and the pulse increase. In addition, the vessels dilate so that metabolic waste products such as lactic acid (lactate) can be removed. Optimal endurance training takes place at the so-called threshold pulse, also known as steady state or aerobic-anaerobic threshold (ANS). This is the point at which the pulse and lactate levels settle to a certain equilibrium at which just enough oxygen is available to the muscles to burn and thus produce energy from carbohydrates and fat (“aerobic” = with air).
Threshold pulse and lactic acid concentration
If the load increases, the muscle cells no longer receive sufficient oxygen and must switch their metabolism to anaerobic energy production (“anaerobic” = without air); increased lactate is produced and exhaustion quickly results.
- Threshold pulse and thus the level of exertion varies from individual to individual and depends primarily on age and resting pulse (which is higher in children, women, and the untrained), on the frequency with which exercise is done, and, within limits, on the type of sport. Resting pulse and pulse changes also vary according to the form of the day, stress, weather, illness and medication. Pulse measurement can also be performed by the layman without effort and automatically with measuring devices that are strapped to the wrist, for example.
- The concentration of lactic acid in the blood before, during and after exercise provides information about the current metabolic situation. For measurement, blood is taken from the earlobe. The lactate value is related to the respective pulse and plotted in a diagram (lactate performance curve). The assessment is left to experts, for example, in sports clinics, which can determine the performance based on the diagram and develop specific training suggestions.
Ergometry
In addition to the measurements of pulse, blood pressure and lactate, ergometry (stress ECG) is used as a direct functional measurement. In it, the work performed, the individual’s maximum capacity, and physical reactions are measured under load (e.g., on a bicycle, treadmill, or stepper) by means of blood pressure, pulse, and cardiac output curve. The load that is started with and its increase up to a defined maximum value (“workload”) is determined by gender, performance ability and possibly the type of sport practiced. However, if subjective discomfort or exhaustion or dangerous ECG changes occur (indicating e.g. heart problems), the examination is stopped before the endurance test. Ergometry is also used for follow-up in heart attack patients.
Borg Scale
This can be used to determine the individual’s perception of exertion. The subject rates on a scale of 6 to 20 how difficult he or she currently feels the work is – depending on his or her subjective shortness of breath. This sensation correlates well with objective measured variables such as pulse (approximately Borg value times 10), oxygen uptake, and lactate values, and thus offers a good way to assess one’s own training status without measuring devices.
Other examinations
There are also specific procedures that are used primarily to analyze how the cardiovascular system and respiration interact. These include, for example, pulmonary function measurement, in which respiratory rate, respiratory minute and breath volume, and oxygen uptake are determined. It is coupled with ergometry as spiroergometry. Since they require more complex equipment, they tend to be reserved for special problems. In performance diagnostics for endurance athletes, there is a whole range of other procedures that are used in addition to or instead of the established lactate performance test and are usually a further development of ergometry or spiroergometry, which means that no blood sample is required.These include, for example, the Conconi test, PWC test, ramp test, Polar OwnZone test, or isokinetic maximum strength test.
