Document Detail


Calcium kinetics during bed rest with artificial gravity and exercise countermeasures.
MedLine Citation:
PMID:  24861908     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
INTRODUCTION: This study aims to assess the potential for artificial gravity (AG) and exercise (EX) to mitigate loss of bone calcium during space flight.
METHODS: We performed two studies: (1) a 21-day bed rest (BR) study with subjects receiving 1 h/day AG (n = 8) or no AG (n = 7) and (2) a 28-day BR study with 1 h/day resistance EX (n = 10) or no EX (n = 3). In both studies, stable isotopes of Ca were administered orally and intravenously, at baseline and after 10 days of BR, and blood, urine, and feces were sampled for up to 14 days post dosing. Tracers were measured using thermal ionization mass spectrometry. Data were analyzed by compartmental modeling.
RESULTS: Less Ca was absorbed during BR, resulting in lower Ca balance in BR+AG (-6.04 ± 3.38 mmol/day, P = 0.023). However, Ca balance did not change with BR+EX, even though absorbed Ca decreased and urinary Ca excretion increased, because endogenous excretion decreased, and there was a trend for increased bone deposition (P = 0.06). Urinary N-telopeptide excretion increased in controls during BR, but not in the EX group. Markers of bone formation were not different between treatment groups for either study. Ca intake decreased during BR (by 5.4 mmol/day in the AG study and 2.8 mmol/day in the EX study), resulting in lower absorbed Ca.
CONCLUSIONS: During BR (or space flight), Ca intake needs to be maintained or even increased with countermeasures such as exercise, to enable maintenance of bone Ca.
Authors:
S M Smith; C Castaneda-Sceppa; K O O'Brien; S A Abrams; P Gillman; N E Brooks; G J Cloutier; M Heer; S R Zwart; M E Wastney
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-5-27
Journal Detail:
Title:  Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA     Volume:  -     ISSN:  1433-2965     ISO Abbreviation:  Osteoporos Int     Publication Date:  2014 May 
Date Detail:
Created Date:  2014-5-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9100105     Medline TA:  Osteoporos Int     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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