According to many dictionaries activity is an inclination and an ability to perform intensive actions, to take up initiative and active part taking. This particular definition shows certain character of activity which is understood as a process illustrating certain dynamics of phenomena both in physical and metaphysical sense.

In reference to the physical world we can state that it is the activity itself as a process is the manifestation of life. It is the activity which formally divides the world into animate and non animate. That is why the phrase life activity is used in order to emphasise the fact that the activity equals life. Taking the above into consideration we can claim that life is a process of continuous activity changing cyclically. Such approach to activity is by far most accurate at every level of organism’s built organisation as both a single cell and highly specialised organism reveal their life activity.

Relating the-afore-described to a human we can say that activity is a basis of our lives. Each cell, organ and system of our body is continually active which indicates to the fact that we are active – that we live. This is a strictly physical approach; however, a human cannot be reduced to a set of specialised cells as the whole metaphysical sphere constituting our self – our personality will be ignored. Therefore this sphere needs to be taken into account when presenting a human being as a complex. Here I would like to present the following figure.

As you can see in the complex view a human being is composed of the physical body and the mind as metaphysical element (understood as our self, our personality – everything which is not physical in us). In such view the brain is classified as neither the body nor the metaphysical element as on one hand it is the body and on the other it constitutes the mind. It is a certain kind of bridge between the body and mind which makes the existence of one without another impossible. It is the body which gives the mind the possibility to exist and the mind is the element controlling the body and making use of its potential – it constitutes the inseparable complex – us.

In such approach physical activity refers to the physical body and is understood as life, existence of this body and thanks to it the existence of the mind. The body is composed of : locomotor system, circulatory system, respiratory system, excretory system, nervous system and others which are active, they live. Such approach to physical activity is true as it illustrates the fact that life of our body is equivalent to activity - life of each cell, each organ and system constituting the body as a complex. This approach emphasises the fact that the disorders of the activity within on system influence the others reducing the activity of the body which affects the mind. The broad understanding of the phrase physical activity is needed to realise that influencing any system of our body we indirectly influence the whole person. It is not difficult to imagine that problems with e.g. circulatory system will have an impact on the functioning of the person.

Whereas customarily in physical culture studies the physical activity is understood as an increased activity of the locomotor system, which is the aforementioned ability to perform intensive action within locomotor system which is considered to be equivalent with physical exercises. Such approach is by far the most appropriate one as it emphasises the sphere of interest in physical culture studies.

Conventionally, physical activity affects the whole organism. Therefore it is regarded as in indicator of health and a way to influence the state of our health. We all understand the notion of health very well. Probably everyone can define health exhaustively.

According to WHO (World Health Organisation) health is: state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.

This definition aims at showing a human being in a complex way which complies with what was previously referred to. It is not only the good physical condition of organism which determines health but also the general psychological and social wellness. It indicates to the fact that we need to view ourselves as a complex in which we do not single out physical activity as something independent of our psyche but combine everything into one organism constituting all elements of the physical and mental built. According to the above approach we have to realise that increasing physical activity by means of exercising we influence not only the locomotor system but also the remaining systems as well as the state of our psyche. That is why it is very important to increase physical activity in our lives as it plays both preventive and in some situations therapeutic role.

The notion of physical activity is connected the notion of ability which denotes the ability perform certain function. Practically it means that if a given system is active and healthy then it is also capable. The important quality of the notion of ability is the possibility of examining a given system as regards functions performed by it. It means that we can evaluate to what extent a given system performs its function. That is why ability is often associated with a given system.