title: Undercarboxylated osteocalcin, muscle strength and indices of bone health in older women.
abstract: We investigated the association between undercarboxylated osteocalcin (ucOC) and lower-limb muscle strength in women over the age of 70years. The study also aims to confirm the association between bone turnover markers and heel ultrasound measures. A post-hoc analysis using data collected as part of a randomized placebo-controlled trial of vitamin D supplementation. An immunoassay was used to quantify total OC (tOC), with hydroxyapatite pre-treatment for ucOC. We determined associations of absolute and relative (ucOC/tOC; ucOC%) measures of ucOC with lower-limb muscle strength, heel ultrasound measures of speed of sound (SOS) and broadband ultrasound attenuation (BUA), bone turnover markers (BTMs; P1NP and CTx) and the acute phase protein alpha-1-antichymotrypsin (α-ACT). ucOC%, but not absolute ucOC concentration, was positively associated with hip flexor, hip abductor and quadriceps muscle strength (all p<0.05). ucOC% was negatively associated with α-ACT (β-coefficient=-0.24, p=0.02). tOC was positively associated with both P1NP and CTx (p<0.001). For each per unit increase in tOC (μg/L) there was a corresponding lower BUA, SOS and SI (β-coefficient = -0.28; -0.23 and -0.23, respectively; all p<0.04). In conclusion, ucOC% is positively associated with muscle strength and negatively associated with α-ACT. These data support a role for ucOC in musculoskeletal interactions in humans. Whilst tOC is associated with bone health, ucOC% and ucOC may also be linked to falls and fracture risk by influencing muscle function.
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), College of Sport and Exercise Science, Victoria University, Melbourne, Australia; Australian Institute of Musculoskeletal Science, NorthWest Academic Centre, The University of Melbourne, Western Health, St Albans, Australia. Electronic address: itamar.levinger@vu.edu.au.
authors.forename: Itamar
authors.initials: I
authors.lastname: Levinger
authors.affiliation: Australian Institute of Musculoskeletal Science, NorthWest Academic Centre, The University of Melbourne, Western Health, St Albans, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Scott
authors.affiliation: Australian Institute of Musculoskeletal Science, NorthWest Academic Centre, The University of Melbourne, Western Health, St Albans, Australia; Rural Clinical School, The University of Queensland, Toowoomba, Australia.
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Nicholson
authors.affiliation: School of Medicine, Deakin University, Geelong, Australia.
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Stuart
authors.affiliation: Ageing Bone Research Program, Sydney Medical School Nepean, The University of Sydney, Sydney, Australia.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Duque
authors.affiliation: Ageing Bone Research Program, Sydney Medical School Nepean, The University of Sydney, Sydney, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: McCorquodale
authors.affiliation: Central Clinical School, Royal Prince Alfred Hospital, The University of Sydney, Sydney, Australia.
authors.forename: Markus
authors.initials: M
authors.lastname: Herrmann
authors.affiliation: Australian Institute of Musculoskeletal Science, NorthWest Academic Centre, The University of Melbourne, Western Health, St Albans, Australia.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ebeling
authors.affiliation: Australian Institute of Musculoskeletal Science, NorthWest Academic Centre, The University of Melbourne, Western Health, St Albans, Australia.
authors.forename: Kerrie M
authors.initials: KM
authors.lastname: Sanders
mesh_terms: D000368:Aged; D015519:Bone Density; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D015675:Osteocalcin / Q000097:blood*; D010919:Placebos
chemical_list: D010919:Placebos; D015675:Osteocalcin
keywords: Bone remodelling; Muscle strength; Older-adults; Osteocalcin; Undercarboxylated osteocalcin