The terms aerobic and anaerobic training are often used in connection with endurance training. But what exactly is behind it, what is the difference and what does a lactate measurement have to do with it? FITBOOK asked two experts.
What do the terms aerobic and anaerobic mean?
“The two terms are related to the metabolic processes in our body. Those that take place with oxygen are aerobic, while those that take place without oxygen are anaerobic,” says Prof. Dr. Billy Sperlich, Professor of Sports Science at the University of Würzburg, on FITBOOK.
Aerobic and anaerobic metabolism run in parallel
This distinction is particularly relevant during training. Because especially when doing sports, our metabolism works at full speed to generate energy. There is often talk of a threshold at which the body “switches” from the aerobic to the anaerobic metabolic range. However, the whole thing is not that simple, explains Prof. Sperlich. «In principle, it is the case with humans that both aerobic and anaerobic metabolic processes take place in parallel in the body even when they are absolutely at rest.» Strictly speaking, there is no such thing as a purely aerobic and anaerobic area. In sports science, attempts are therefore being made to find out the ratio of aerobic and anaerobic processes involved in metabolism during training.
How can you determine your personal aerobic or anaerobic threshold?
To determine the ratio of aerobic and anaerobic processes during exercise, lactate is measured. «Lactate is the anion of lactic acid and is a waste product of anaerobic metabolism when the body converts sugar into lactic acid,» explains Dr. medical Paul Schmidt-Hellinger from the Department of Sports Medicine at the Charité Berlin in an interview with FITBOOK. In order to find out when the body switches from the predominantly aerobic to the anaerobic area, the increase in the lactate level in the blood is measured.
Lactate is basically already present in the human body. The content is given in moles. By determining the lactate value, one can determine the personal aerobic or anaerobic threshold. “The basic level of lactate in the blood is between one and two millimoles. The aerobic threshold now describes the point at which the lactate level in the blood exceeds this value for the first time,» explains Dr. Schmidt-Hellinger. The anaerobic threshold, on the other hand, is when the lactate level has exceeded the aerobic threshold by at least 1.5 millimoles. Experts also refer to this point as “lactate steady state”. Put simply, this means that lactate formation and lactate breakdown are just about in balance with one another. If you continue to increase the physical exertion, the lactate level rises faster and stronger from this point, and exhaustion occurs.
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This is how the lactate measurement works with the step test
In order to measure the lactate during exercise, the so-called step test is typically carried out. How it works is explained by Dr. Schmidt-Hellinger as follows: “As the name implies, the test is carried out in stages. The athlete is allowed to run at different speeds, around four, six, eight, ten and twelve kilometers per hour for three minutes. After each stage, there is a 30-second pause and a little blood is taken to determine the lactate value,” explains the doctor.
The heart rate is also measured. This value can give the athlete information about which heart rate range he should use as a guide during training in order to train either aerobically or anaerobically. «However, one has to take into account in this context that the heart rate is not a completely reliable value for determining the aerobic and anaerobic zone,» notes Dr. Schmidt-Hellinger is clear on this. It often also depends on external factors, such as the outside temperature, and can therefore vary greatly.
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How much does a lactate test cost – and do you have to pay for it yourself?
Such a sports medicine lactate test can be very useful for athletes who are working towards a certain goal. «Many health insurance companies even contribute up to 90 percent of the costs,» says Dr. Schmidt-Hellinger. He recommends inquiring directly with your own health insurance company. In the Charité in Berlin, for example, they offer lactate measurement as part of a sports medical check-up for around 150 euros.
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Can you tell if you’re training aerobically or anaerobically?
But is it actually possible to tell purely from physical signals and without measuring lactate whether you are training predominantly aerobically or anaerobically? “Of course, you cannot determine this with complete certainty without a measurement. In any case, the so-called talking test is helpful. That means quite simply: If you can still talk to your running partner during training, for example, there is a high probability that you are training in the aerobic area,» says Dr. Schmidt-Hellinger on FITBOOK. However, if you are still so fit in terms of breathing that you could theoretically even sing, there is no training effect. The change to the anaerobic area can best be determined by the subjective feeling – like the feeling of having to gasp for air and impending exhaustion.
Does lactate lead to acidification of the muscles?
For a long time, lactate was considered a real enemy of effective training. One should definitely avoid sports in the anaerobic area, was the advice that was often given. «The main reason is that lactate is often confused with lactic acid itself and is therefore held responsible for over-acidification of the muscles,» says Dr. Schmidt-Hellinger. However, that is not entirely correct. “On the contrary, as an anion, lactate can even scavenge the accumulation of acid in the muscle. All in all, of course, the muscle acidifies under strong anaerobic stress,” he clarifies.
This is also confirmed by Prof. Sperlich. «We now know from many studies that anaerobic exercise, such as the popular HIIT training, can have a positive impact on our metabolic processes,» says the sports scientist.
When should you train aerobically and when should you train anaerobically?
«Whether you should train aerobically or anaerobically depends primarily on your personal training goal,» says Dr. Schmidt-Hellinger. If you want to improve your own aerobic or anaerobic threshold, he advises training in the moderate anaerobic range and thus setting a gentle training impulse. “Of course you shouldn’t overtax your body, but you should still give it a little incentive. This is the only way to ultimately achieve a training effect and an improvement in endurance,” explains the doctor.
You can follow the rule that about two thirds of the training should take place in the aerobic to very low anaerobic range and one third should actually take place in the intensive anaerobic range. It is also important to take breaks of around 48 hours between training sessions so that the body can regenerate and adapt to the training stimuli.
However, if you do weight training and want to build as many muscles as possible, according to Dr. Schmidt-Hellinger mainly rely on anaerobic strength training. «It’s all about training for maximum strength. Therefore, the training stimulus must extend to muscular exhaustion in order to achieve an effect.” Additional high-intensity endurance training is not beneficial. «The training impulses are otherwise in competition with each other and block each other,» says the sports doctor. As a strength athlete, endurance training should take place in a “relaxed” aerobic area as a warm-up and cool-down.