Each person is unique, and this uniqueness is determined by his or her constitution or a set of individual features, which are dependant on heredity and living conditions. This constitution determines how the person perceives internal and external influences. Thus, people of different constitutions will respond differently to one and the same influence. An important feature of constitution is the tone of the autonomic nervous system or, to put it more simply, the control-system. It determines how the organism reacts to various influences.

There exist three main types of control-systems: vagotonic, amphotonic and sympathicotonic. Let us simplify the terminology by defining:

People with mild regulation are characterized by slow adaptation to any influence. They are not disposed to displaying emotions and keep them inside. Their pulse rate is slightly below the average.

People with strict regulation quickly get used to external influences, vigorously display their emotions and have an increased pulse rate.

The intermediary group is made up of people with mixed regulation. They can display the characteristics of both strict and mild regulation.

In the course of a lifetime, the type of regulation can shift to either direction, depending on external and internal influences.

When practicing sport it is important to remember that people with different types of regulation stand physical loads differently. People with mild regulation slowly adapt to loads but, once used to them, can endure a load for a prolonged time. People with this type of regulation are mostly stayers. They are better suited to cyclic types of physical exertion: cycling, cross-country skiing, medium and long-distance running, swimming, etc.

People with strict regulation quickly get used to loads and can better stand large short-term exertions. They usually have the features of a sprinter. They are better suited to acyclic physical exertion: wrestling, boxing, calisthenics, etc.

It is also important to know that when the body is strained it can display a type of regulation that is not characteristic of the person. For example, a person may normally have mixed regulation but when the body is strained, the regulation becomes strict. This is why it is often sufficient to determine the dominant type of regulation in order to diagnose the presence of body tension. If the tension was absent before, its probable cause is high exertion.

As a rule, the highest tension in the body is observed with strict regulation, and the lowest tension—with mixed regulation. With age, the tension of the body systems increases and the number of people with strict regulation also rises.