Undercarboxylated osteocalcin, muscle strength and indices of bone health in older women.

Itamar Levinger, David Scott, Geoffrey C Nicholson, Amanda L Stuart, Gustavo Duque, Thomas McCorquodale, Markus Herrmann, Peter R Ebeling, Kerrie M Sanders

Journal: Bone 2015;64():8-12

PMID: 24662619

Full Text on Elsevier Science View on PubMed

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.

Address: 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: [email protected].; Australian Institute of Musculoskeletal Science, NorthWest Academic Centre, The University of Melbourne, Western Health, St Albans, Australia.; 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.; School of Medicine, Deakin University, Geelong, Australia.; Ageing Bone Research Program, Sydney Medical School Nepean, The University of Sydney, Sydney, Australia.; Central Clinical School, Royal Prince Alfred Hospital, The University of Sydney, Sydney, Australia.

DOI: 10.1016/j.bone.2014.03.008

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MeSH Terms: Aged, Bone Density, Double-Blind Method, Female, Humans, Osteocalcin, Placebos