title: Markers of bone metabolism during 14 days of bed rest in young and older men.
abstract: We aimed at comparing markers of bone metabolism during unloading in young and older men, and to assess countermeasure effectiveness.
  
  
  
  16 older (60±2 years) and 8 younger men (23±3 years) underwent bed rest (BR) for 14 days. A subgroup of the Older performed cognitive training during BR and supplemented protein and potassium bicarbonate afterwards. Biochemical markers of bone and calcium/phosphate metabolism were assessed.
  
  
  
  At baseline urinary NTX and CTX were greater in younger than in older subjects (P<0.001), but increased during BR (P<0.001) by a similar amount (P>0.17). P1NP was greater in young than in older subjects (P<0.001) and decreased during BR in the Young (P<0.001). Sclerostin increased during BR across groups (P=0.016). No systematic effects of the countermeasure were observed.
  
  
  
  In men, older age did not affect control of bone metabolism, but bone turnover was reduced. During BR formation markers were reduced only in younger men whereas resorption markers increased to a comparable extent. Thus, we assume that older men are not at an elevated, and possibly even at a reduced risk to lose bone when immobilized.
authors.affiliation: Department of Nutrition and Food Science, University of Bonn, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Buehlmeier
authors.forename: P
authors.initials: P
authors.lastname: Frings-Meuthen
authors.forename: N
authors.initials: N
authors.lastname: Mohorko
authors.forename: P
authors.initials: P
authors.lastname: Lau
authors.forename: S
authors.initials: S
authors.lastname: Mazzucco
authors.forename: J L
authors.initials: JL
authors.lastname: Ferretti
authors.forename: G
authors.initials: G
authors.lastname: Biolo
authors.forename: R
authors.initials: R
authors.lastname: Pisot
authors.forename: B
authors.initials: B
authors.lastname: Simunic
authors.forename: J
authors.initials: J
authors.lastname: Rittweger
mesh_terms: D000375:Aging / Q000378:metabolism*; D001510:Bed Rest / Q000009:adverse effects / Q000639:trends*; D015415:Biomarkers / Q000378:metabolism; D016723:Bone Remodeling / Q000502:physiology*; D001862:Bone Resorption / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers