Effects of Spaceflight on Cardiovascular Physiology and Health.

During spaceflight, the human cardiovascular system undergoes major changes primarily related to the effects of decreased gravitational force, or microgravity, on the human body. These changes present challenges to human adaptation and operation in space. This article reviews the knowledge gained in human experiments in the past half century of spaceflight, and summarizes our knowledge on the effects of short- and long-duration microgravity exposure on cardiovascular physiology and functioning, including fluid redistribution, autonomic reflexes, cardiac parameters, orthostatic intolerance, arrhythmias, aerobic capacity, and cardiac atrophy. This review also discusses current countermeasures for risk reduction during spaceflight, as well as future directions in cardiovascular research in space.