title: Bisphosphonates as a supplement to exercise to protect bone during long-duration spaceflight.
abstract: We report the results of alendronate ingestion plus exercise in preventing the declines in bone mass and strength and elevated levels of urinary calcium and bone resorption in astronauts during 5.5 months of spaceflight.
  
  
  BACKGROUND
  This investigation was an international collaboration between NASA and the JAXA space agencies to investigate the potential value of antiresorptive agents to mitigate the well-established bone changes associated with long-duration spaceflight.
  
  
  METHODS
  We report the results from seven International Space Station (ISS) astronauts who spent a mean of 5.5 months on the ISS and who took an oral dose of 70 mg of alendronate weekly starting 3 weeks before flight and continuing throughout the mission. All crewmembers had available for exercise a treadmill, cycle ergometer, and a resistance exercise device. Our assessment included densitometry of multiple bone regions using X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) and assays of biomarkers of bone metabolism.
  
  
  RESULTS
  In addition to pre- and post-flight measurements, we compared our results to 18 astronauts who flew ISS missions and who exercised using an early model resistance exercise device, called the interim resistance exercise device, and to 11 ISS astronauts who exercised using the newer advanced resistance exercise device (ARED). Our findings indicate that the ARED provided significant attenuation of bone loss compared with the older device although post-flight decreases in the femur neck and hip remained. The combination of the ARED and bisphosphonate attenuated the expected decline in essentially all indices of altered bone physiology during spaceflight including: DXA-determined losses in bone mineral density of the spine, hip, and pelvis, QCT-determined compartmental losses in trabecular and cortical bone mass in the hip, calculated measures of fall and stance computed bone strength of the hip, elevated levels of bone resorption markers, and urinary excretion of calcium.
  
  
  CONCLUSIONS
  The combination of exercise plus an antiresoptive drug may be useful for protecting bone health during long-duration spaceflight.
authors: Universities Space Research Association, 3600 Bay Area Blvd, Houston, TX 77058, USA. leblanc@dsls.usra.edu
authors: A
authors: A
authors: Leblanc
authors: T
authors: T
authors: Matsumoto
authors: J
authors: J
authors: Jones
authors: J
authors: J
authors: Shapiro
authors: T
authors: T
authors: Lang
authors: L
authors: L
authors: Shackelford
authors: S M
authors: SM
authors: Smith
authors: H
authors: H
authors: Evans
authors: E
authors: E
authors: Spector
authors: R
authors: R
authors: Ploutz-Snyder
authors: J
authors: J
authors: Sibonga
authors: J
authors: J
authors: Keyak
authors: T
authors: T
authors: Nakamura
authors: K
authors: K
authors: Kohri
authors: H
authors: H
authors: Ohshima
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D019386:Alendronate / Q000008:administration & dosage / Q000627:therapeutic use*; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001823:Body Composition / Q000502:physiology; D015519:Bone Density / Q000187:drug effects / Q000502:physiology; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001862:Bone Resorption / Q000209:etiology / Q000517:prevention & control; D003131:Combined Modality Therapy; D004334:Drug Administration Schedule; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D013026:Space Flight; D014893:Weightlessness / Q000009:adverse effects
chemical_list: D015415:Biomarkers; D050071:Bone Density Conservation Agents; D019386:Alendronate