UNLABELLED: We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest. Subjects ingested less calcium during bed rest, and with artificial gravity, they also absorbed less calcium. With exercise, they excreted less calcium. To retain bone during bed rest, calcium intake needs to be maintained. 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.
UNLABELLED: We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest. Subjects ingested less calcium during bed rest, and with artificial gravity, they also absorbed less calcium. With exercise, they excreted less calcium. To retain bone during bed rest, calcium intake needs to be maintained. 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 R Zwart; G E Crawford; P L Gillman; G Kala; A S Rodgers; A Rogers; A M Inniss; B L Rice; K Ericson; S Coburn; Y Bourbeau; E Hudson; G Mathew; D E Dekerlegand; C F Sams; M A Heer; W H Paloski; S M Smith Journal: J Appl Physiol (1985) Date: 2008-12-12
Authors: G Armbrecht; D L Belavý; U Gast; M Bongrazio; F Touby; G Beller; H J Roth; F H Perschel; J Rittweger; D Felsenberg Journal: Osteoporos Int Date: 2009-06-18 Impact factor: 4.507
Authors: Scott M Smith; Martina A Heer; Linda C Shackelford; Jean D Sibonga; Lori Ploutz-Snyder; Sara R Zwart Journal: J Bone Miner Res Date: 2012-09 Impact factor: 6.741
Authors: S M Smith; S R Zwart; M A Heer; N Baecker; H J Evans; A H Feiveson; L C Shackelford; A D Leblanc Journal: J Appl Physiol (1985) Date: 2008-12-12
Authors: Naomi Brooks; Gregory J Cloutier; Samuel M Cadena; Jennifer E Layne; Carol A Nelsen; Alicia M Freed; Ronenn Roubenoff; Carmen Castaneda-Sceppa Journal: J Appl Physiol (1985) Date: 2008-05-15
Authors: Scott M Smith; Sara R Zwart; Martina Heer; Edgar K Hudson; Linda Shackelford; Jennifer Ll Morgan Journal: J Bone Miner Res Date: 2014-07 Impact factor: 6.741
Authors: Thomas Lang; Jack J W A Van Loon; Susan Bloomfield; Laurence Vico; Angele Chopard; Joern Rittweger; Antonios Kyparos; Dieter Blottner; Ilkka Vuori; Rupert Gerzer; Peter R Cavanagh Journal: NPJ Microgravity Date: 2017-02-14 Impact factor: 4.415