Past research has shown that spaceflight can have an effect on the human cardiovascular system. Even brief periods of exposure to reduced gravity environments can result in cardiovascular changes such as fluid shifts, changes in total blood volume, heartbeat and heart rhythm irregularities, and diminished aerobic capacity.
The cardiovascular effects of spaceflight may outlast the duration of the mission itself. When crewmembers return to Earth gravity, symptoms such as difficulty standing, low blood pressure, and even fainting have been observed. These responses could hinder crewmembers' ability to act quickly in an emergency landing situation. Because future missions will involve extended stays in space, HRP researchers are working diligently to develop methods of reducing or reversing cardiovascular irregularities associated with exposure to microgravity.
At present, a protocol that combines physical exercise, balanced nutrition, and medication as needed helps modulate crewmembers' cardiovascular function in space. In addition, scientists and doctors use post-flight rehabilitation and observation programs to ensure that crewmembers' cardiovascular systems transition safely back to Earth conditions.
Current and future research projects will focus on further investigating the extent of de-conditioning to the heart, pre-screening for heart disease, and developing in-flight medical diagnostics for better understanding of the ways in which the heart changes and functions differently during prolonged exposure to reduced gravity. Only after investigators understand these changes more fully can they develop more effective countermeasures to help modulate the human cardiovascular system in space.