Physical activity is a basic physiological need of both children and adults. Even though we do not perceive a lack of physical activity as intensively as we perceive a lack of food or liquids (hunger, thirst), physical activity is indispensable for the right development and functioning of human organs.

From birth a child’s muscular system develops thanks to natural movement (crawling, climbing etc.) thus building the muscle corset which is necessary for the correct development of the skeleton and good body posture in different natural positions: sitting, standing, walking, running, etc. Body movement enhances the functioning of internal organs and accompanies almost every mental activity of a child.

The amount of physical activities in pre-schoolers often takes up several hours a day. Yet according to the recommendations of many authors including American sources (e.g. NASPE), the minimal requirement regarding spontaneous physical activity is merely 60 minutes a day, which we consider as insufficient. However, experts recommend supplementing spontaneous physical activities with directed ones, lasting at least 60 minutes.

Following the beginning of compulsory school attendance, children’s spontaneous activity quickly disappears and a sedentary way of life starts to prevail: sitting at the school desk, over their homework, in front of the television, at the computer, on different means of transport, etc. This excessively lowers the physical strain on the organism, weakens the muscle apparatus and worsens the child’s overall physical fitness. The lack of physical activity leads, apart from other things, to muscle imbalance, which at the beginning shows itself in a slouched body posture causing progressive development of orthopaedic problems later. Such weakening is currently a serious health problem in primary school children, and, according to the latest research, it concerns 50% of the child population.

The absence of aerobic strain (i.e. a longer lasting strain on big muscle groups) contributes to the development of cardiovascular, respiratory as well as endocrine diseases and adds to being overweight and obesity, i.e. it negatively affects body composition.

Therefore physical activity is an essential part of human life and an investment for the future for both children and adults. It is not necessary to assign excessive importance to the level of physical performance or achieved sports results. We should rather focus on the development of positive attitudes and interest children take in physical activity, which should result in lifelong physical activity as part of their healthy lifestyle. To achieve this we need to understand the basic requirements regarding the physical strain on a human organism and comprehend the significance of health-oriented fitness. To make this concept clear for teachers who do not have specialised instruction in physical education, the following text presents some examples relevant to both children and adults.