The effects of microgravity on the human organism have been studied for over 60 years. The experience of short- and long-term space flights revealed alterations in multiple physiological systems either in the course of the flight or afterward. Some of these changes represent serious risks for crew health and functional capacity. This fact served as the trigger for multiple countries with space program participants to develop spaceflight countermeasures and medical support systems. These activities are intended to counteract space flight effects such as axial and support unloading, muscle disuse, monotony, fluid redistribution, sensory deficit, etc. Some countermeasures have been adapted from Earth medicine and sports, while others have been created especially for space flights. Many of the observed space flight effects have similarities to conditions seen on Earth, such as: decrease of motor activity in aging people, immobilized patients, and professions associated with forced physical inactivity and isolation. Thus, many space countermeasures and medical support systems can be applied in Earth medicine and rehabilitation. For example, countermeasures like loading suits, lower body negative pressure suits, electromyostimulation of various regimens, water-salt supplements, vestibular training means, etc. have been used in Earth medicine and sports conditioning over the last 20 years.