Performance diagnostics in endurance sports

There are many rumors, half-truths and assumptions about the meaning and nonsense of performance-diagnostic methods. Reason enough for us to present and discuss current processes in an up-to-date overview.

Performance diagnostics can help to understand the current performance status and to adjust the training based on the results. Individual athletic goals can be prepared in such a way that physiological adjustments can be controlled and the profile of the target performance can be worked on.

When it comes to the "how" of proper training, as an athlete you need to get workable recommendations. The question is at what level of intensity and with which physiological adaptation mechanisms a training should be implemented.

The maximum heart rate is not suitable!

In the basic literature on endurance training, there are still indications of deriving the training ranges from the maximum heart rate. It is assumed that certain adjustments are attributed to a certain percentage distribution of the maximum heart rate. Controlling the training is about estimating the form of energy harvesting under stress and using the training methods and intensities in training to create improvements. The maximum heart rate, however, is not suitable for exercise control because it is an individual size that may differ more than 30 beats in its maximum severity. (1) The percentage distribution of the maximum heart rate can not be considered objective and valid Method used to determine a training zone. The goal is rather to measure the metabolism under stress and to draw conclusions on the training load based on it. (Also read: Training Control: Heart Rate Variability (HRV))

Methods for determining endurance performance

Basically, two methods for determining the endurance performance can be distinguished, in sports practice these concepts z. T. also be combined with each other. While determining lactate concentration should provide clues to muscle metabolism, spiroergometry - measuring respiratory gases under stress - can provide clues to oxygen uptake, CO2 exhalation, and associated computational parameters. Both methods have advantages and disadvantages, each of which presupposes that the practicing physician or sports scientist masters the current physiological foundations of the methods. Contrary to common semantics in many textbooks, however, one can not speak of a "gold standard" (1). For every question must be weighed which method or which combination of methods based on the individual examination objective can bring the correct knowledge. A blanket answer according to the "best" method is just as impossible as the evaluation of a method according to "accuracy". Both aspects will be revisited and discussed in a later section.

What is a threshold model?

Both in lactate diagnostics and in spiroergometry, the term "threshold" has become established. (1, 2) In each case two thresholds are described in both examination methods. T. have similar names, but content to describe completely different metabolic situations. Nevertheless, in practice, the thresholds are often equated. Both in lactate diagnostics and in spiroergometry there are different methods to describe the thresholds or to identify them during the test. From the mere presence of many different calculation methods in lactate diagnostics, it is often concluded in popular scientific publications that lactate diagnostics are less "valid", as the thresholds often reflect different times in a stress test. However, these statements are incorrect because different threshold models also consider different questions and specific test situations. (1) For example, while the threshold model according to Dickhuth is very well suited to analyze in step tests on a radar with very small gradations, (1) the Threshold according to Simon in certain field trial variants in game sports are meaningfully used. (1) The long scientific debate with questions about lactate diagnostics is the real reason for the existence of many different threshold models and can not be seen as a disadvantage. The question must rather be which model is suitable for which test and how the training areas of a particular athlete can be deduced from the examination.

The thresholds in lactate diagnostics

In the definition of thresholds, the ultimate goal is to distinguish aerobic metabolic rates from anaerobic levels. (1) It must therefore be recognized when and for how long the metabolism dominates the aerobic regime or when the mixing of aerobic and anaerobic energy supply into a dominant anaerobic metabolism tilts. The latter is more likely to be detected by spiroergometry and will therefore be highlighted in the next issue of Trainingsworld Sportexperten Report. Within lactate diagnostics, the aerobic threshold can be differentiated from the anaerobic threshold (1). The aerobic threshold is the area where your metabolism leaves the predominantly aerobic muscle metabolism and increasingly has to supply anaerobic energy supply components with high-energy phosphates (ATP). A synonymous name for the aerobic threshold is the term Laktatthreshold (LT), which is often incorrectly equated with the anerobic threshold. In the area of ​​the individual anaerobic threshold (IAS), lactate production is now rising sharply and lactate production and lactate elimination are losing their balance, so that the lactate concentration begins to increase more strongly.

What does the increase in lactate concentration say?

Lactate has long been considered a "metabolic end product", with recent findings indicating that lactate is likely to be more of a metabolic intermediate. (3) Lactate is produced exclusively in anaerobic carbohydrate metabolism when energy is generated in the body from glucose without oxygen. In this context, it is often claimed that the cardiovascular system is unable to provide the working muscles with sufficient oxygen, so for this reason the body must be forced to work anaerobically. This reasoning is wrong, because in the working musculature is always sufficient oxygen available. Rather, the anaerobic carbohydrate metabolism causes more amounts of energy-yielding phosphates in a given time. Lactate is thus increasingly produced when the energy supply of aerobic glycolysis and aerobic lipid metabolism can not produce sufficient ATP in the working musculature. The existing resting lactate levels and increase in lactate during exercise are less due to lack of oxygen than due to the fact that some areas of the body work obligately anaerobically and this metabolic situation can provide more energy. In this context, it should be noted that the approach to lactate has changed significantly in recent years. (2, 3) In response to these changes in view, lactate performance diagnostics must also respond to their advice or interpretation of the metabolism. It is even questionable whether a "threshold" can exist in principle, or whether rather fluent metabolic transitions are to be assumed. To conclude from this that lactate diagnostics is not practicable, however, is wrong, since the kinetics of the lactate curve - ie the form of the image of the measurement points - provides valuable information about the metabolism. (1) Basically, any performance diagnostic procedure has sources of error that need to be controlled so that the athlete can be consulted with the results of a test.

The changed view on lactate

While lactate has long been considered a metabolic waste, new physiological approaches show that this molecule can gain energy from lactate in muscles that have very high anaerobic metabolism. This ability was attributed to the heart muscle alone for many years. In addition, blood lactate concentrations do not appear to be determined solely by the rate of glycolysis, but also depend on the limiting factors of lactate transport. (3)

Conclusion

A lactate performance diagnostic spiroergometry provides important insights into the functionality and current state of performance of a trained athlete. We would like to take up these questions again in the second part of the article and further deepen the overview of performance diagnostics.

Dennis Sandig

Literature:

1. Swiss Journal of Sports Medicine and Sports Traumatology, 2001, vol. 2 (49), p. 57-66.

2nd German Journal of Sports Medicine, 2011, Vol. 4 (62), p. 92-97.

3. Swiss Journal of Sports Medicine and Sports Traumatology, 2009, Vol. 3 (57), pp. 100-107.

Leave A Response

Your Email Address Will Not Be Published. Required Fields Are Marked*