How do NASA astronauts maintain their strength in space?

Bones lose calcium, the mineral from which they derive their structure and strength, through the process of demineralization. If enough calcium is lost, the skeletal system becomes weaker and less capable of withstanding the stresses associated with daily life on Earth. read more

Exercising in space is not just for fun; it is necessary to keep astronauts healthy and functional. On Earth, gravity works against our muscles and bones every time we move. This requires our bodies to maintain enough muscle and bone mass to support our own weight. read more

Astronauts on the International Space Station work out about two hours a day, using treadmills, exercise bikes, and an IRED--a device specially developed to allow astronauts to do resistive or strength training. read more

Living in space is not the same as living on Earth. In space, astronauts' bodies change. On Earth, our lower body and legs carry our weight. This helps keep our bones and muscles strong. In space, astronauts float. They do not use their legs much. Their lower backs begin to lose strength. Their leg muscles do too. The bones begin to get weak and thin. read more