title: Objectively measured physical activity and vitamin D status in older people from Germany.
abstract: BACKGROUND
  To analyse the seasonal relationship of objectively measured physical activity with vitamin D status in older persons from Southern Germany (latitude: 48.4°N).
  
  
  METHODS
  Physical activity was assessed in 1193 community-dwelling individuals aged ≥65 years (58% men) over 1 week using a thigh-worn accelerometer. Furthermore, the 25-hydroxyvitamin D (25(OH)D) level was measured. Least-square means of 25(OH)D serum levels were calculated for quartiles of average daily walking duration stratified by season and adjusted for gender, age and body mass index. Participants with prescribed vitamin D supplements were excluded.
  
  
  RESULTS
  Statistically significant linear associations between quartiles of walking duration with 25(OH)D serum levels were observed in all seasons but not in summer. Differences in 25(OH)D serum levels between the first and the last quartile were 3.42 ng/mL (p=0.002) in winter, 2.80 ng/mL (p=0.009) in spring, and 3.60 ng/mL (p<0.001) in the fall. The proportion of vitamin D insufficiency (<20 ng/mL) even in the highest quartile of walking duration was 45.3% in winter, 73.7% in spring, 17.4% in summer and 16.5% in the fall.
  
  
  CONCLUSIONS
  Although a positive dose-response relationship was seen between walking duration and the 25(OH)D serum level for most seasons, vitamin D insufficiency was still very prevalent even in high-active persons during all seasons.
authors.affiliation: Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany Department of Clinical Gerontology, Robert-Bosch-Hospital, Stuttgart, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Klenk
authors.affiliation: Department of Clinical Gerontology, Robert-Bosch-Hospital, Stuttgart, Germany.
authors.forename: Kilian
authors.initials: K
authors.lastname: Rapp
authors.affiliation: Agaplesion Bethesda Clinic, Ulm, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Denkinger
authors.affiliation: Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Nagel
authors.affiliation: Agaplesion Bethesda Clinic, Ulm, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Nikolaus
authors.affiliation: Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Peter
authors.affiliation: Division of Endocrinology, Department of Internal Medicine I, University of Ulm Medical Centre, Ulm, Germany LKC School of Medicine, Imperial College London and Nanyang Technological University, Singapore, Singapore.
authors.forename: Bernhard O
authors.initials: BO
authors.lastname: Boehm
authors.affiliation: Department of Internal Medicine II-Cardiology, University of Ulm Medical Centre, Ulm, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Koenig
authors.affiliation: Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany.
authors.forename: Dietrich
authors.initials: D
authors.lastname: Rothenbacher
mesh_terms: D061725:Accelerometry / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D000368:Aged; D015992:Body Mass Index; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004522:Educational Status; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D016018:Least-Squares Analysis; D016014:Linear Models; D008297:Male; D009043:Motor Activity; D015995:Prevalence; D012621:Seasons; D013472:Sunlight; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology; D016138:Walking / Q000706:statistics & numerical data*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: ELDERLY; GERONTOLOGY; PHYSICAL ACTIVITY; PUBLIC HEALTH; SEASONAL