title: Effect of calendar age on physical performance: A comparison of standard clinical measures with instrumented measures in middle-aged to older adults.
abstract: BACKGROUND
  Decline in physical performance is highly prevalent during aging. Identification of sensitive markers of age-related changes in physical performance is important for early detection, development of therapeutic strategies and insight into underlying mechanisms. We studied the association of calendar age and familial longevity with standard clinical and instrumented measures of physical performance in a cohort of healthy middle-aged to older adults.
  
  
  METHODS
  Cross-sectional analysis within the Leiden Longevity Study consisting of offspring of nonagenarian siblings and their partners (n=300, mean age (SD) 65.3 (6.7) years). Standard clinical measures were 25-meter walking speed and total duration of the chair stand test (CST). Instrumented measures were determined using a body fixed sensor. Dependence of physical performance on calendar age and familial longevity (offspring versus partner status) was analyzed using linear and logistic regression, respectively, adjusted for gender and height.
  
  
  RESULTS
  Higher calendar age was associated with slower walking speed and longer duration of the CST (standardized β (95% CI) -.024 (-.042; -.006) and .035 (.014;.056), respectively). Instrumented measures showed similar effect sizes with strongest associations for gait stability and symmetry in mediolateral direction and for the extension and flexion phase of sit-to-stand and stand-to-sit transfers, respectively. No differences were observed between offspring of nonagenarian siblings and their partners.
  
  
  CONCLUSIONS
  Standard clinical and instrumented measures of physical performance are associated with similar effect size to age-related changes in physical performance observable from middle age. The potential added value of instrumented measures for understanding underlying mechanisms requires further attention.
authors.affiliation: Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands; Department of Internal Medicine, Section of Gerontology and Geriatrics, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: m.stijntjes@lumc.nl.
authors.forename: M
authors.initials: M
authors.lastname: Stijntjes
authors.affiliation: Department of Rehabilitation Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: C G M
authors.initials: CG
authors.lastname: Meskers
authors.affiliation: Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: A J M
authors.initials: AJ
authors.lastname: de Craen
authors.affiliation: McRoberts, The Hague, The Netherlands.
authors.forename: R C
authors.initials: RC
authors.lastname: van Lummel
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University, Amsterdam, The Netherlands.
authors.forename: S M
authors.initials: SM
authors.lastname: Rispens
authors.affiliation: Department of Medical Statistics, Section of Molecular Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: P E
authors.initials: PE
authors.lastname: Slagboom
authors.affiliation: Department of Internal Medicine, Section of Gerontology and Geriatrics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: A B
authors.initials: AB
authors.lastname: Maier
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D013997:Time Factors
keywords: Aging; Body fixed sensor; Calendar age; Familial longevity; Physical performance