title: A prospective study of the associations between 25-hydroxy-vitamin D, sarcopenia progression and physical activity in older adults.
abstract: OBJECTIVE
  Low 25-hydroxyvitamin D (25OHD) levels may be associated with both sarcopenia (the age-related decline in muscle mass and function) and low physical activity (PA). Our objective was to describe prospective associations between 25OHD, muscle parameters, and PA in community-dwelling older adults.
  
  
  METHODS
  Prospective, population-based study with a mean follow-up of 2·6 ± 0·4 years.
  
  
  METHODS
  Six hundred and eighty-six community-dwelling older adults (49% women; mean ± SD 62 ± 7 years old).
  
  
  METHODS
  Appendicular lean mass percentage (%ALM) and body fat assessed by Dual-energy X-ray Absorptiometry, leg strength by dynamometer, leg muscle quality (LMQ), PA assessed by pedometer, self-reported sun exposure by questionnaire, and serum 25OHD measured by radioimmunoassay.
  
  
  RESULTS
  Participants with 25OHD ≤50 nM had lower mean %ALM, leg strength, LMQ and PA (all P < 0·05). As a continuous function, baseline 25OHD was a positive independent predictor of change in leg strength (β = 5·74 kg, 95% CI 0·65, 10·82) and LMQ (β = 0·49 kg/kg, 95% CI 0·17, 0·82). Also, change in 25OHD was positively predicted by baseline %ALM (β = 2·03 pM/p.a., 95% CI 0·44, 3·62) leg strength (β = 0·30 pM/p.a., 95% CI 0·06, 0·53), LMQ (β = 4·48 pM/p.a., 95% CI 0·36, 8·61) and PA (β = 2·63 pM/p.a., 95% CI 0·35, 4·92) after adjustment for sun exposure and body fat.
  
  
  CONCLUSIONS
  25OHD may be important for the maintenance of muscle function, and higher skeletal muscle mass and function as well as general PA levels may also be beneficial for 25OHD status, in community-dwelling older adults.
authors.affiliation: Menzies Research Institute, University of Tasmania, Hobart School of Human Life Sciences, University of Tasmania, Launceston, Tas, Australia. dsscott@utas.edu.au
authors.forename: David
authors.initials: D
authors.lastname: Scott
authors.forename: Leigh
authors.initials: L
authors.lastname: Blizzard
authors.forename: James
authors.initials: J
authors.lastname: Fell
authors.forename: Changhai
authors.initials: C
authors.lastname: Ding
authors.forename: Tania
authors.initials: T
authors.lastname: Winzenberg
authors.forename: Graeme
authors.initials: G
authors.lastname: Jones
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D005260:Female; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology; D011446:Prospective Studies; D055948:Sarcopenia / Q000209:etiology*; D013648:Tasmania; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D