Background: As the scientific support for the impact of physical activity on health has grown, physical activity recommendations for the public have been modified. The aim of the paper is to present the evolution of physical activity guidelines, which were formulated on the basis of existing research evidence, produced by experts, mainly in physiology and medicine.Material/Methods: A systematic literature review was applied. In order to interpret the content of text data, a qualitative content analysis was used. It was supported by the Qualitative Data Analysis (QDA) computer software package NVivo 9.Results: Recognition of hazards of a sedentary lifestyle has led numerous groups to promulgate public health recommendations for physical activity. Since 1950s leading scientists and science organisations have participated in developing and publicising these guidelines and in revising them to keep up with the pace of modern exercise science. The paper discusses reasons for differences in the guidelines and provides a summary in order to harmonize existing reports.Conclusions: Using epidemiological, clinical and laboratory methods, different expert committees have independently arrived at similar conclusions about the need for physical activity in daily life. However, formulating guidelines regarding an optimal dose of physical activity, which could be universal for everybody, is very problematic. A recommended dose of physical activity must be approachable and adjusted to a particular person or a group.