Metabolic syndrome is one of the pre-nosological conditions that implies strain on several systems of the body and disruption of all types of metabolism. The key components of the syndrome are visceral obesity, peripheral tissue insulin resistance, arterial hypertension and non-alcoholic fatty liver disease. There is a number of diseases associated with the syndrome, which makes diagnosing its preclinical manifestations important. Overweight and obesity only continue spreading; moreover, these conditions are registered in people of increasingly younger age. Metabolic syndrome in childhood increases the risk of cardiovascular disease in adulthood. Top tier athletes are no exception. Some sports and playing roles promote body weight growth. A young athlete may have specific constitutional features, and, without proper control, motivating such athletes to grow muscles means they also grow fat. The recommendation is to pay special attention to children under the age of 11 that play rugby, American football as line men, in heavy weight categories. Application of the latest diagnostic criteria with their actualization on a regular basis, as well as search for additional markers and parameters identifiable in laboratory settings, would ensure adjustment of the athlete's condition in a timely manner.