"The results for ICV showed that the human heart adapts well to microgravity," said Levine. "Especially early in flight, the heart volume gets smaller, and blood flows a little more slowly into the heart. As the astronauts get into their exercise countermeasure in space, however, they are able to overcome this initial deconditioning response. For some astronauts, especially those who were less fit prior to flight, they actually developed physiological hypertrophy, similar to an athlete's heart."
According to Levine, the research showed that there was nothing magical about microgravity and the heart. The heart adapted to the load that was placed upon it - if the load reduced, the heart would atrophy; but, if the load increased, there was nothing about microgravity that prevented the heart from responding appropriately. In addition, this study showed that spaceflight by itself does not cause cardiac arrhythmias--a problem that had been worrisome for many years. Astronauts who have lots of extra heart beats on Earth, have them also in space, but these do not increase in number or severity, nor are the fundamental electrical properties of the heart altered by spaceflight.
These results have important implications for aging - individuals who keep up their fitness over a lifetime are able to preserve the youthful flexibility of the heart and blood vessels, just like ast
|Contact: Laura Niles|
NASA/Johnson Space Center