Question: does the heart rate change from when you are on earth to when you are in space?

Julia Attias answered on 5 Dec 2015:

Yes – the heart rate slows down in space. Astronauts get lots more blood in their chests and head in space than on Earth because they are in a floating posture, meaning that their hearts don’t have to work as hard to push blood all the way from the legs back to the heart (which happens when we stand up because gravity forces it down to our legs!). So, it has a chance to relax a little, and not do as much work, which means it doesn’t have to beat as fast!