Key points from article :
Spaceflight reduces both heart rate and blood pressure and increases the amount of blood pumped by the heart.
Alexa Wnorowski at Stanford University in California performed experiments using human heart cells.
Put on a SpaceX spacecraft travelling to the International Space Station for a resupply mission.
After five and a half weeks scientists examined the effects of microgravity on them.
Amount 3,000 changes, notable ones were to genes responsible for metabolism and mitochondria.
Most returned to normal after 10 days back on Earth.
