Space Does a Body Good? Not really. In low gravity muscles and bones atrophy from lack of use. When the astronauts return to Earth, the muscle and bone loss can be dangerous. They can develop a condition similar to osteoporosis, a disease that results in a significant amount of bone loss. Other potential problems include fluid redistribution, a slowing of the cardiovascular system, decreased production of red blood cells, balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, excess flatulence, and puffiness of the face. The effects, however, reverse quickly when the astronauts return to Earth.
Regular exercise is critical to the health of the astronauts because it counteracts the effects of living for long periods of time in low gravity. Astronauts on the International Space Station exercise on stationary bikes and treadmills, and a device that allows weigh lifting.
Tomorrow, The US Space Shuttle Fleet Rita Bay