The central adjustments to your training

Experienced endurance athletes know that regular exercise does not necessarily lead to weight loss. This fact has a discouraging effect on many people, yet a longer-term training in your organism causes positive changes.

At the beginning of each year, our good intentions are still present in our minds. One of the most popular good intentions is certainly changing the lifestyle towards a healthier behavior. More exercise, less sweets and maybe a few pounds less body weight. Endurance training is the tool of choice.

A central positive effect of regular endurance training is the change in body composition in favor of the musculature. The fat content is reduced and the working musculature is changing. Since fat mass weighs less than lean muscle mass, it is not surprising if, despite positive changes in your silhouette, you can not find any weight loss on your body scales. Intense exercise usually leads to weight gain. (1)

Endurance - the psychophysical fatigue resistance of the athlete

Physical endurance is the fatigue resistance of the whole organism or its subsystems - it means the ability to maintain a certain performance over a long period of time. Psychic endurance is understood to mean the ability of an athlete to resist a stimulus that calls for the termination of a strain as long as possible. This is colloquially referred to as "staying power". Regular endurance training therefore makes you more resistant and fitter in everyday life.

From a biological point of view, endurance capacity is based on the metabolic capacity of the working musculature and the transport capacity of the blood circulation. Thus it is dependent on the energy metabolism, the ability to absorb oxygen, the optimal body weight, the technology economy, the will to persevere and the conditioning endurance capability. (2)

Two types of endurance: aerobic and anaerobic

Depending on how you look at it, endurance can be divided into different ways in terms of appearance. In terms of muscular energy supply, these are aerobic and anaerobic endurance. In aerobic endurance, the energy your body needs to perform the exercise is provided by aerobic glycolysis. This means that the nutrients are burned using oxygen. Anaerobic endurance provides energy without the use of oxygen through anaerobic glycolysis. A purely aerobic or anaerobic energy supply, however, never takes place. It is always a hybrid of both systems. Depending on load duration and intensity, the proportions of energy-providing systems vary. (2)

The adaptation process of your organism

The adaptation processes to physical stress in the human organism affect the muscle cell and the cardiovascular system. The cardiovascular system represents the auxiliary mechanism that fulfills the needs of cell metabolism. The training-induced biochemical adaptation processes at cell level are described below.

Energy - increasing the storage capacity

To do mechanical work, the muscle needs energy in the form of ATP. He wins this over the burning of nutrients like glucose or free fatty acids. These substrates are transported via the bloodstream from the glycogen depot of the liver or of the subcutaneous fatty tissue to the working muscle cell. Glycogen plays a major role here, as the brain constantly requires glucose to work and, in oxygen deficiency situations, only glucose can be burned via anaerobic glycolysis, but not fat.

However, the muscle also has its own glycogen or triglyceride storage. Endurance exercise, depending on the intensity and duration of a more or less pronounced emptying of glycogen stores. With regular training and thus regular emptying there is an increase in energy storage. Muscle and liver glycogen reserves can increase up to double. The glycogen reserves in the untrained 200-300 g in the muscles and 60-100 g in the liver.

It is important that once stored muscle glycogen can not leave the cell and is therefore not available for blood sugar regulation. Only liver glycogen can be used to regulate blood sugar. Likewise, the intracellular fat stores multiply. This is very important. The longer the muscles can gain energy through their own reserves, the longer the energy reserves of the liver are spared and guarantee a supply of the brain. They stay focused longer and better cope with cognitive demands.

The power plants are also adapting

Increasing the energy stores in the muscle leads to an increase in activity and an increase in the enzymes that convert this energy. Depending on whether the athlete exercises more aerobically or anaerobically or both, either the enzyme activity in the mitochondria, the place of aerobic energy production, or in the sarcoplasm, the place of anaerobic energy production, or both. As a prerequisite, there is of course also an increase and enlargement of the mitochondria and thus to an increased energy throughput capacity. Incidentally, trained athletes are better able to eliminate accumulated lactate from the blood than untrained people. (3)

Become more relaxed

Through endurance training, there are also various changes and adaptation of the hormonal system. Thus, with increasing endurance performance with the same performance, not only reduced lactate production but also lower levels of stress hormones are released. The heart nerves sympathetic and parasympathetic regulate with their transmitters epinephrine and norepinephrine the adaptations of the organism to strains. They regulate cardiovascular activity in a way that is appropriate to the stress. Thus, trained athletes recover faster because their organism is faster able to switch from a sympathicotone situation, ie an activity-oriented metabolic situation, to a vagotone situation, ie to a resting and rest-oriented metabolic situation.

Briefly noted

- Important to note: aerobic exercise loads increase the capacity of the aerobic metabolism, anaerobic exercise loads increase the capacity of the anaerobic metabolism and thus the ability to work despite high acidity. (1)

The cardiovascular system

In order for the mechanisms described above to work optimally in the working muscle cell, the oxygen demand of the muscle cell and the supply of oxygen must remain in balance. For this, the cardiovascular system is responsible for the following mechanisms: The oxygen and substrate transport to the muscle and the removal of metabolic waste products take place via the bloodstream.

The metabolism is localized in the capillaries, the smallest blood vessels that permeate the body tissues (for example, muscles). An essential parameter for the metabolic efficiency of the muscle is thus the increased blood flow through the dilation of the arterioles and the enlargement of the capillary bed and thus the increase of the exchange surface in the musculature. Thus, the residence time of the blood in the capillaries remains normal, it comes to vasodilatation or -engstellung in non-loaded regions and thus to a redistribution of blood, so compared to about 20% at rest in stress about 80% of the supply of working muscles benefits.

Although the relative concentration of erythrocytes and hemoglobin does not change as a result of endurance training, there is also an adaptation process in the area of ​​the blood. Thus, there is an increase in blood volume, primarily determined by an increase in the plasma volume up to 2 liters. Thus, the total hemoglobin content increases. (3)

Endurance athletes have big hearts

However, the most important adaptation within the cardiovascular system takes place in the heart itself. By endurance training it comes with appropriate intensity and sufficient extent to the training of an "athlete's heart". When the athlete's heart, the heart cavities, which is called dilatation enlarge, and it comes to hypertrophy of the heart walls. Unbalanced heart weights range from 250-300 g with a volume of approximately 600-800 ml. Trained ones have hearts of 350-500 g severity with a volume of 900-1300 ml. Increasing the size of the heart is an essential prerequisite for increasing the size of the heart stroke volume. A high stroke volume forms the basis for an economic cardiac work of the athlete in the submaximal range as well as a prerequisite for the increase in oxygen absorption capacity required in endurance exercise.

Effects of well-trained basic stamina: (2)

- Increasing physical performance

- Fat burning starts earlier and still serves as a primary source of energy with increasing loads

- Optimization of the recovery ability

- Minimization of injuries

- Increase mental resilience


Arterioles - small arteries, ie blood vessels, through which oxygen-rich, fresh blood flows into the tissue

Erythrocytes - red blood cells

Hemoglobin - iron-containing, oxygen-transporting proteins in the red blood cells; Hemoglobin is also referred to as a red blood pigment because of its color

Stroke volume - Stroke volume refers to the volume of blood or the amount of blood ejected from the heart during a heartbeat


1. Nsca's performance training journal, 2008, Vol. 7 (1), pp. 19-21.

2. Weineck, J. (2003), Optimal Training. Ballingen: Spitta Verlag GmbH & Co. KG.

3. Dickhuth, H.-H. (2000), Introduction to Sports and Performance Medicine. Volume 16: Sports and Physical Education. Schorndorf: Publisher Karl Hofmann.

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