Astronauts, while they're in space, also lose muscle mass and strength. NASA-sponsored research is helping to understand the genes, hormones, and signals that regulate these responses in muscles. Ultimately, we hope to use this knowledge to prevent or minimize muscle loss. This capability would be tremendously important not just for NASA, but for all the people who, like my patient, lose strength and muscle mass after illnesses or operations. Another problem facing millions of aging Americans is osteoporosis.
Osteoporosis occurs when calcium is lost from the bones and the bones weaken.
The fractures that often result from osteoporosis can lead to permanent loss of mobility and even death. Bone loss is a problem for astronauts as well. The amount of calcium that appears in an astronaut's urine during space flight is high and stays high as long as the individual remains weightless. This means that the bones sense the reduced load placed on them and they respond by losing calcium. The increased calcium in the urine can lead to kidney stones, and a continuous loss of calcium weakens bone.