Bedrest volunteer using a Galileo Space resistive exercise machine. The footrests vibrate to exercise the leg muscles.
Putting people in bed lying with their heads 6° below the horizontal for long periods causes their bodies to react in similar ways to being weightless, but is cheaper and safer than sending them into space.
Bedrest studies can answer questions on how our bodies adapt to living in space and on how our bodies adapt to growing old. Many of the findings from bedrest studies apply directly to people on Earth.