title: Motor function is associated with 1,25(OH)(2)D and indices of insulin-glucose dynamics in non-diabetic older adults.
abstract: BACKGROUND
  Advancing age is accompanied by changes in metabolic characteristics, such as reduced insulin sensitivity and low levels of vitamin D, which may exacerbate age-related declines in physical function.
  
  
  OBJECTIVE
  The aim of the present study was to determine the associations between insulin-glucose dynamics, vitamin D metabolites, and performance on a battery of motor tasks in healthy, non-diabetic older adults.
  
  
  METHODS
  Sixty-nine community-dwelling men and women (65-90 years) were recruited. Insulin-glucose dynamics were determined by an intravenous glucose tolerance test, and vitamin D metabolites were measured. Motor function was characterized by the time to walk 500 m, chair-rise time, lower body strength, dorsiflexor steadiness and endurance time, and muscle coactivation.
  
  
  RESULTS
  Significant unadjusted correlations were found between insulin-glucose dynamics and 1,25-dihydroxyvitamin D [1,25(OH)2D] with walk time, strength, steadiness, endurance time, and muscle activation (p < 0.05). A significant amount of the variance in walking endurance was explained by the sex of the individual, 1,25(OH)2D, and fasting blood insulin (R (2) = 0.36, p < 0.001). Strength could be partially explained by age, body fatness, and fasting glucose (R (2) = 0.55, p < 0.001).
  
  
  CONCLUSIONS
  Poor motor function in non-diabetic older men and women was associated with indices of insulin-glucose dynamics and the bio-active vitamin D metabolite 1,25(OH)2D. Walking endurance and strength were explained by 1,25(OH)2D and fasting blood glucose and insulin, even after adjusting for age, sex, and body fat.
  
  
  CONCLUSIONS
  Motor function in a relatively small sample of non-diabetic older men and women was associated with metabolic factors that increase in prevalence with aging.
authors.affiliation: University of Colorado Boulder, 354 UCB, Boulder, CO, 80309-0354, USA, Jamie.Justice@colorado.edu.
authors.forename: Jamie N
authors.initials: JN
authors.lastname: Justice
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Pierpoint
authors.forename: Diba
authors.initials: D
authors.lastname: Mani
authors.forename: Robert S
authors.initials: RS
authors.lastname: Schwartz
authors.forename: Roger M
authors.initials: RM
authors.lastname: Enoka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood* / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D009048:Motor Skills; D053580:Muscle Strength; D010807:Physical Endurance; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D001786:Blood Glucose; D007328:Insulin; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D