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Objectively measured physical activity is associated with parameters of bone in 70-year-old men and women
Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Geriatric Medicine. Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine. (IHsport)
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. (IHsport)
Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Geriatric Medicine. (IHsport)
2015 (English)In: Bone, ISSN 8756-3282, E-ISSN 1873-2763, Vol. 81, p. 72-79Article in journal (Refereed) Published
Abstract [en]

As the world's population ages, the occurrence of osteoporosis-related fractures is projected to increase. Low areal bone mineral density (aBMD), a well-known risk factor for fractures, may be influenced by physical activity (PA). In this cross-sectional study, we aimed to investigate potential associations between objective measures of PA and bone properties, in a population-based cohort of 1228 70-year-old men and women. We measured volumetric BMD (vBMD, mg/cm3) together with cross-sectional area (CSA, mm2) by peripheral quantitative computed tomography at sites located 4% and 66% in the distal–proximal trajectory at the tibia and radius. We also measured aBMD (g/cm2) by dual energy X-ray absorptiometry at the femoral neck, lumbar spine (L1–L4) and radius. Participants wore triaxial accelerometers for 7 consecutive days to obtain objective estimates of PA. The intensity of the objective PA was divided into light (100–1951 counts/min [CPM]), moderate (1952– 5724 cpm) and vigorous (≥5725 cpm). Maximal accelerations for the anterior–posterior (z), medio-lateral (x), and vertical (y) axes were also separately assessed. Associations were investigated using bivariate correlations and multiple linear regression, adjusted for height, weight and sex. Vigorous PA showed the strongest association with femoral neck aBMD (β = 0.09, p b 0.001), while both moderate and vigorous PAs were associated with cor- tical area and trabecular vBMD in the weight-bearing tibia (all p b 0.05). Peak vertical accelerations were associated significantly with cortical area (β = 0.09, p b 0.001) and trabecular vBMD (β = 0.09, p = 0.001) of the tibia, whereas peak anterior–posterior accelerations showed no correlation with these properties. No positive association was found between objectively measured PA and bone parameters of the radius. In conclusion, vertical accelerations and moderate to vigorous PA independently predict bone properties, especially in the weight-bearing tibia, in 70-year-old men and women. 

Place, publisher, year, edition, pages
Elsevier, 2015. Vol. 81, p. 72-79
Keywords [en]
Physical activity, Aging, Peripheral quantitative computed tomography, Accelerometer, Volumetric BMD
National Category
Geriatrics
Identifiers
URN: urn:nbn:se:umu:diva-112194DOI: 10.1016/j.bone.2015.07.001ISI: 000365372800011PubMedID: 26151120OAI: oai:DiVA.org:umu-112194DiVA, id: diva2:876439
Funder
Swedish Research Council, 2011-2976Available from: 2015-12-03 Created: 2015-12-03 Last updated: 2018-06-07Bibliographically approved
In thesis
1. The Healthy Ageing Initiative: Prevention of falls and fractures
Open this publication in new window or tab >>The Healthy Ageing Initiative: Prevention of falls and fractures
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The world is currently experiencing a dramatic increase in the number of older individuals, an amount that is expected to double between 2015 and 2050. This increase will likely affect the prevalence of age-related functional impairments, such as those caused by fractures. Fractures are often immobilizing events leading to increased individual suffering and vast healthcare costs. Prevention of these events and detection of underlying risk factors are hence of utmost importance. Fracture prevention strategies have traditionally focused on strengthening the skeleton by improving bone mineral density, partly through the mechanical load of increased physical activity. However, research has shown that nine out of ten hip fractures are attributed to falls. While several risk factors behind falls have been identified, there is less knowledge about how aspects such as gait patterns and postural stability predict future falls. The aim of this thesis was to expand upon the current knowledge by investigating objective measures of physical activity in relation to bone parameters, and measures of gait patterns and postural stability in relation to incident falls, in a large population-based sample of 70-year-olds.

The samples investigated in the four included studies were drawn from the Healthy Ageing Initiative (HAI) cohort. Study I examined associations between physical activity, objectively measured using accelerometers, and bone parameters, measured by Dual-energy X-ray Absorptiometry and Peripheral Quantitative Computed Tomography. Study II examined how gait variability, measured using the GAITRite electronic walkway system, predicted incident falls in men and women. Studies III and IV examined how center of pressure (COP) sway and limits of stability (LOS), measured using a force platform, predicted incident falls. Independent prediction of bone parameters and incident falls were investigated using multiple linear and logistic regression models.

Study I revealed that moderate-to-vigorous physical activity and vertical peak acceleration independently predicted parameters of bone in the weight-bearing skeleton. Study II showed that women’s increased risk of falling could be explained by increased gait variability during dual-task assignments. Study III revealed that the risk of falling was increased by 75-90% for individuals in the highest quintile of COP sway. Study IV integrated COP and LOS data, showing that fall risk was increased by 9-16% per 1-unit increase in COP-LOS ratio. In conclusion, this thesis highlighted several objective predictors of incident falls among older adults. Future studies and recommendations should emphasize strategies to improve balance, muscle strength and physical activity in order to prevent falls and fractures.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2018. p. 52
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1944
Keywords
prospective falls, cohort study, fall risk, gait variability, postural stability, physical activity, bone properties, objective measurements, older individuals
National Category
Public Health, Global Health, Social Medicine and Epidemiology Geriatrics
Identifiers
urn:nbn:se:umu:diva-143873 (URN)978-91-7601-830-9 (ISBN)
Public defence
2018-02-09, KBE303 (Stora hörsalen), KBC-huset, Umeå, 09:00 (Swedish)
Opponent
Supervisors
Funder
Swedish Research Council, 2011-2976
Available from: 2018-01-19 Created: 2018-01-15 Last updated: 2018-06-09Bibliographically approved

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Johansson, JonasNordström, AnnaNordström, Peter

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