Adaptation of the Skeletal System during Long-duration Spaceflight Running Title: Skeletal Adaptation in Space

This review will highlight evidence from crew members flown on space missions >90 days to suggest that the adaptations of the skeletal system to mechanical unloading may predispose crew members to an accelerated onset of osteoporosis after return to Earth. By definition, osteoporosis is a skeletal disorder − characterized by low bone mineral density and structural deterioration − that reduces the ability of bones to resist fracture under the loading of normal daily activities. “Involutional” or agerelated osteoporosis is readily recognized as a syndrome afflicting the elderly population because of the insipid and asymptomatic nature of bone loss that does not typically manifest as fractures until after age 1 https://ntrs.nasa.gov/search.jsp?R=20080014098 2017-09-14T00:49:53+00:00Z