title: Is calcaneal stiffness more sensitive to physical activity than forearm bone mineral density? A population-based study of persons aged 20-79 years.
abstract: OBJECTIVE
  The aim of this study was to investigate the associations between forearm bone mineral density (BMD), calcaneal stiffness, and physical activity levels in a normal population using different non-invasive methods.
  
  
  METHODS
  The participants were invited to undergo bone measurements using single photon absorptiometry of the forearm and quantitative ultrasound (QUS) of the calcaneal bone, and also to complete a questionnaire. Physical activity levels were designated low, moderate, and high in the question on leisure-time activity.
  
  
  RESULTS
  There were 956 participants included in the present study. Forearm BMD in the eighth age decade was 0.40 g/cm2 (95% CI 0.33-0.46 g/cm2) lower than in the third decade among women and 0.28 g/cm2 (95% CI 0.18-0.37 g/cm2) lower among men. The differences in calcaneal stiffness between the same age decades were 22.4 (95% CI 17.5-27.4) among women and 15.8 (95% CI 8.0-23.5) among men. The correlation between forearm BMD and calcaneal stiffness was 0.58 (95% CI 0.52-0.64) in women and 0.34 (95% CI 0.25-0.42) in men. Reported moderate and high leisure-time activity levels in both genders were associated with higher calcaneal stiffness but not with forearm BMD.
  
  
  CONCLUSIONS
  The QUS may be used to measure the effect of present physical activity levels on calcaneal bone at the population level. Further longitudinal studies are warranted in order to determine the most appropriate non-invasive method in population-based studies.
authors.affiliation: Primary Health Care Laboratory, Vadstena, Sweden. lotta.grahn-kronhed@telia.com
authors.forename: Ann-Charlotte
authors.initials: AC
authors.lastname: Grahn Kronhed
authors.forename: Inger
authors.initials: I
authors.lastname: Knutsson
authors.forename: Owe
authors.initials: O
authors.lastname: Löfman
authors.forename: Toomas
authors.initials: T
authors.lastname: Timpka
authors.forename: Göran
authors.initials: G
authors.lastname: Toss
authors.forename: Margareta
authors.initials: M
authors.lastname: Möller
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D015519:Bone Density; D002111:Calcaneus / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D005542:Forearm / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000175:diagnosis* / Q000517:prevention & control; D011877:Radionuclide Imaging; D011795:Surveys and Questionnaires; D013548:Sweden; D014463:Ultrasonography