Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis, remains a disease of unknown etiology. The conduct of adequate research in this area is complicated by the absence of a biological marker of the disease, its heterogeneous nature and the lack of a clear idea of the factors which are at the origin of the development of the pathology and which are the consequence. Nevertheless, in recent years, it has been possible to identify a certain number of predisposing, start-up and support factors for the CSA.

In particular, it has been shown that a number of infectious diseases, such as Epstein-Barr virus, Q fever and viral meningitis, can cause CFS. There was no relationship between the development of this pathology and the incidence of colds and persistent infections of a different genesis. The role of the immune system in the development of CFS is also not completely clear, however, it appears that the immune response to physical activity in people who suffer from it may be insufficient. CFS occurs more often in women; the causes of this phenomenon are unknown, although more and more facts indicate the presence of a genetic predisposition.

Risk markers for the development of chronic fatigue syndrome are considered premorbid disorders of the mental state and frequent requests for medical help for various benign diseases in the past 15 years. Another prognostic factor, according to some authors, could be a sedentary lifestyle. According to recent studies, 10-year-olds who, according to their parents, practically do not participate in sports games in their spare time, are twice as likely to develop CFS in adulthood.

However, it remains unclear whether inactivity is the cause of the occurrence or only a marker for the disease. It is believed that patients suffering from this pathology devote more effort to physical activity than healthy individuals and focus more on the internal sensations of their own body (phenomenon of interception). It has been shown that a sedentary lifestyle improves the degree of sensations that arise when it is necessary to show physical activity, the condition is aggravated by the body's reluctance to stress, mental and emotional disorders. The resulting state of interception, in turn, helps reduce physical activity. When they are then exposed to the corresponding starting factor, these people may suffer from CFS.

This concept is based on a number of therapeutic measures aimed at "reprogramming" the state of interception in chronic fatigue syndrome, such as physical exercises with progressive loading and cognitive behavioral therapy.