title: Short-arm centrifugation as a partially effective musculoskeletal countermeasure during 5-day head-down tilt bed rest--results from the BRAG1 study.
abstract: OBJECTIVE
  Human centrifugation, also called artificial gravity (AG), is proposed as a combined strategy against detrimental effects of microgravity in long-term space missions. This study scrutinized human short-arm centrifugation as countermeasure against musculoskeletal de-conditioning.
  
  
  METHODS
  Eleven healthy male subjects [mean age of 34 (SD 7) years] completed the cross-over trial, including three campaigns of -6° head-down tilt bed rest (HDT) for 5 days, with preceding baseline data collection and recovery phases. Bed rest without AG was used as control condition (Ctrl), and AG with 1 g at the center of mass applied once per day for 30 min in one bout (AG1×30) and in 6 bouts of 5 min (AG6×5, 3-min rest between bouts) as experimental conditions. End-points were muscle strength, vertical jump performance, and biomarkers of bone and protein metabolism.
  
  
  RESULTS
  AG6×5 was better tolerated than AG1×30. Bone resorption markers CTX, NTX, and DPD all increased by approximately 25 % toward the end of bed rest (P < 0.001), and nitrogen balance decreased by approximately 3 g/day (P < 0.001), without any protection by AG (P > 0.4). Decreases in vertical jump height by 2.1 (SE 0.6) cm after Ctrl bed rest was prevented by either of the AG protocols (P = 0.039).
  
  
  CONCLUSIONS
  The present study yielded succinct catabolic effects upon muscle and bone metabolism that were un-prevented by AG. The preservation of vertical jump performance by AG in this study is likely caused by central nervous rather than by peripheral musculoskeletal effects.
authors: Institute of Aerospace Medicine, German Aerosapce Center (DLR), Linder Höhe 1, 51147, Cologne, Germany, joern.rittweger@dlr.de.
authors: Jörn
authors: J
authors: Rittweger
authors: Marie-Pierre
authors: MP
authors: Bareille
authors: Gilles
authors: G
authors: Clément
authors: Dag
authors: D
authors: Linnarsson
authors: William H
authors: WH
authors: Paloski
authors: Floris
authors: F
authors: Wuyts
authors: Jochen
authors: J
authors: Zange
authors: Oliver
authors: O
authors: Angerer
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000378:metabolism; D001510:Bed Rest; D001862:Bone Resorption / Q000209:etiology / Q000517:prevention & control*; D001842:Bone and Bones / Q000378:metabolism / Q000502:physiology; D002498:Centrifugation; D024042:Collagen Type I / Q000378:metabolism; D018470:Gravity, Altered; D018475:Head-Down Tilt; D006801:Humans; D008297:Male; D009068:Movement; D018908:Muscle Weakness / Q000209:etiology / Q000517:prevention & control*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D011347:Procollagen / Q000378:metabolism
chemical_list: D000596:Amino Acids; D024042:Collagen Type I; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; C036020:deoxypyridinoline