title: Fifty years of human space travel: implications for bone and calcium research.
abstract: Calcium and bone metabolism remain key concerns for space travelers, and ground-based models of space flight have provided a vast literature to complement the smaller set of reports from flight studies. Increased bone resorption and largely unchanged bone formation result in the loss of calcium and bone mineral during space flight, which alters the endocrine regulation of calcium metabolism. Physical, pharmacologic, and nutritional means have been used to counteract these changes. In 2012, heavy resistance exercise plus good nutritional and vitamin D status were demonstrated to reduce loss of bone mineral density on long-duration International Space Station missions. Uncertainty continues to exist, however, as to whether the bone is as strong after flight as it was before flight and whether nutritional and exercise prescriptions can be optimized during space flight. Findings from these studies not only will help future space explorers but also will broaden our understanding of the regulation of bone and calcium homeostasis on Earth.
authors.affiliation: Biomedical Research and Environmental Sciences Division, NASA Lyndon B. Johnson Space Center, Houston, Texas 77058; email: scott.m.smith@nasa.gov.
authors.forename: S M
authors.initials: SM
authors.lastname: Smith
authors.forename: S A
authors.initials: SA
authors.lastname: Abrams
authors.forename: J E
authors.initials: JE
authors.lastname: Davis-Street
authors.forename: M
authors.initials: M
authors.lastname: Heer
authors.forename: K O
authors.initials: KO
authors.lastname: O'Brien
authors.forename: M E
authors.initials: ME
authors.lastname: Wastney
authors.forename: S R
authors.initials: SR
authors.lastname: Zwart
mesh_terms: D000818:Animals; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D001846:Bone Development; D001862:Bone Resorption / Q000209:etiology* / Q000378:metabolism / Q000517:prevention & control; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D002136:Calcium, Dietary / Q000378:metabolism / Q000627:therapeutic use; D019317:Evidence-Based Medicine; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D008954:Models, Biological; D009752:Nutritional Status; D055070:Resistance Training; D013026:Space Flight / Q000266:history*; D014807:Vitamin D / Q000378:metabolism / Q000627:therapeutic use; D014893:Weightlessness / Q000009:adverse effects*
chemical_list: D050071:Bone Density Conservation Agents; D002136:Calcium, Dietary; D014807:Vitamin D
keywords: acid-base balance; bed rest; bone mineral density; exercise; microgravity; vitamin D