title: [Preventive effects of exercise training on bone loss during 21 d -6 degrees head down bed-rest].
abstract: OBJECTIVE
  To observe the protective effects of exercise training during 21 d -6 degrees head down bed rest (HDBR) on bone loss.
  
  
  METHODS
  Ten healthy young men were randomly divided into HDBR group and HD-BR exercise group, with 5 in each group. Both groups were exposed to -6 degrees head down bed rest for 21 d. The subjects in the exercise group performed exercise with a bicycle ergometer in supine position 1 h/d during bed rest. Femur bone mineral density (BMD), serum bone gla protein (BGP) as well as hydroxyproline/creatinine (HOP/Cr) were determined before and during 20 d HDBR.
  
  
  RESULTS
  As compared with the before HDBR values, average femur BMD decreased by 5.8% and 0.9% for HDBR group and HDBR and exercise group respectively. HOP/Cr significantly increased in the HDBR group and was significantly higher than the HDBR exercise group. BGP decreased in both groups with no significant difference.
  
  
  CONCLUSIONS
  Exercise during 21 d -6 degrees HDBR is beneficial in preventing bone loss.
authors.affiliation: Institute of Space Medico-Engineering, Beijing, China.
authors.forename: Yu-sheng
authors.initials: YS
authors.lastname: Liu
authors.forename: Wei-fen
authors.initials: WF
authors.lastname: Huang
authors.forename: Li-ping
authors.initials: LP
authors.lastname: Li
authors.forename: Chong-fa
authors.initials: CF
authors.lastname: Zhong
authors.forename: Rong-di
authors.initials: RD
authors.lastname: Dong
authors.forename: Hong-yi
authors.initials: HY
authors.lastname: Sun
mesh_terms: D000293:Adolescent; D000328:Adult; D001510:Bed Rest; D018488:Bone Demineralization, Pathologic / Q000517:prevention & control*; D015519:Bone Density; D003404:Creatinine / Q000378:metabolism; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D005081:Exercise Therapy; D005269:Femur / Q000378:metabolism / Q000502:physiology / Q000503:physiopathology; D018475:Head-Down Tilt; D006801:Humans; D006909:Hydroxyproline / Q000378:metabolism; D008297:Male; D015675:Osteocalcin / Q000378:metabolism; D010281:Parathyroid Hormone / Q000378:metabolism; D018544:Weightlessness Countermeasures; D018474:Weightlessness Simulation
chemical_list: D010281:Parathyroid Hormone; D015675:Osteocalcin; D003404:Creatinine; D006909:Hydroxyproline