title: Evaluating the relationship between muscle and bone modeling response in older adults.
abstract: Bone modeling, the process that continually adjusts bone strength in response to prevalent muscle-loading forces throughout an individual's lifespan, may play an important role in bone fragility with age. Femoral stress, an index of bone modeling response, can be estimated using measurements of DXA derived bone geometry and loading information incorporated into an engineering model. Assuming that individuals have adapted to habitual muscle loading forces, greater stresses indicate a diminished response and a weaker bone. The purpose of this paper was to evaluate the associations of lean mass and muscle strength with the femoral stress measure generated from the engineering model and to examine the extent to which lean mass and muscle strength account for variation in femoral stress among 2539 healthy older adults participating in the Health ABC study using linear regression. Mean femoral stress was higher in women (9.51, SD=1.85Mpa) than in men (8.02, SD=1.43Mpa). Percent lean mass explained more of the variation in femoral stress than did knee strength adjusted for body size (R(2)=0.187 vs. 0.055 in men; R(2)=0.237 vs. 0.095 in women). In models adjusted for potential confounders, for every percent increase in lean mass, mean femoral stress was 0.121Mpa lower (95% CI: -0.138, -0.104; p<0.001) in men and 0.139Mpa lower (95% CI: -0.158, -0.121; p<0.001) in women. The inverse association of femoral stress with lean mass and with knee strength did not differ by category of BMI. Results from this study provide insight into bone modeling differences as measured by femoral stress among older men and women and indicate that lean mass may capture elements of bone's response to load.
authors.affiliation: Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, United States. Electronic address: lsemani1@jhu.edu.
authors.forename: Lisa
authors.initials: L
authors.lastname: Reider
authors.affiliation: Beck Radiological Innovations, Inc., United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Beck
authors.affiliation: Center for Medicare and Medicaid Innovation, Centers for Medicare and Medicaid Services, Baltimore, MD, United States.
authors.forename: Dawn
authors.initials: D
authors.lastname: Alley
authors.affiliation: Novartis Institute for Biomedical Research, United States; Department of Epidemiology and Public Health, University of Maryland, School of Medicine, United States.
authors.forename: Ram
authors.initials: R
authors.lastname: Miller
authors.affiliation: National Institute on Aging, Longitudinal Study Section, United States.
authors.forename: Michelle
authors.initials: M
authors.lastname: Shardell
authors.affiliation: Department of Sociology and Anthropology, University of Maryland Baltimore County, United States.
authors.forename: John
authors.initials: J
authors.lastname: Schumacher
authors.affiliation: University of Maryland, School of Medicine, United States.
authors.forename: Jay
authors.initials: J
authors.lastname: Magaziner
authors.affiliation: Research Institute, California Pacific Medical Center, San Francisco, CA, United States; Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, United States.
authors.forename: Peggy M
authors.initials: PM
authors.lastname: Cawthon
authors.affiliation: National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control, United States.
authors.forename: Kamil E
authors.initials: KE
authors.lastname: Barbour
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, United States.
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.affiliation: Laboratory of Epidemiology and Population Sciences Intramural Research Program, National Institute on Aging, United States.
authors.forename: Tamara
authors.initials: T
authors.lastname: Harris
mesh_terms: D000368:Aged; D015992:Body Mass Index; D049628:Body Size; D001842:Bone and Bones / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D005269:Femur / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007717:Knee / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009132:Muscles / Q000473:pathology* / Q000503:physiopathology; D013314:Stress, Mechanical; D013851:Thinness / Q000473:pathology / Q000503:physiopathology; D016474:Weight-Bearing
keywords: Bone modeling response; Femoral stress; Muscle