Poster Presentation 33rd ASM of the Australian & New Zealand Bone & Mineral Society 2023

Bone mineral density and sedentary ageing: a cross-sectional analysis (#220)

Julie A Pasco 1 2 , Kara B Anderson 1 , Kara L Holloway-Kew 1 , Lana J Williams 1 , Natalie K Hyde 1 , Pamela Rufus-Membere 1 , Mark A Kotowicz 1 2
  1. Deakin University, IMPACT-Institute for Mental and Physical Health and Clinical Translation, Geelong, VICTORIA, Australia
  2. Department of Medicine-Western Health, University of Melbourne, St Albans, VICTORIA, Australia

Introduction

Physical activity, particularly weight-bearing exercise and resistance training, are recommended for maintaining bone health during ageing. We investigated age-related patterns of bone mineral density (BMD) in association with non-specific physical activity levels.

Methods

Participants were 1021 women and 1397 men (aged 20-96y) from the Geelong Osteoporosis Study. Femoral neck BMD was measured using Lunar densitometers (DPX-L for women; DPX-L or Prodigy-Pro for men). Physical activity was self-reported using a 7-point mobility scale ranging from ‘very active’ to ‘unable to walk’ based on Metabolic Equivalent of Task values; descriptors for each intensity category were provided. For analyses, groups were collapsed into very-active, active and sedentary levels. Associations between physical activity and age were explored using sex-stratified multivariable regression models, in which cubic age adjustments were made for women, and linear adjustments were made for age for men and for weight for both sexes.

Results

For men, 305 (21.8%) were sedentary, 803 (57.5%) active and 289 (20.7%) very-active; for women numbers were 211 (20.7%), 542 (53.1%) and 268 (26.2%). For men, BMD increased with increasing levels of physical activity across all age groups (Figure). For women the pattern was less consistent. Regression modelling showed that for men, compared to the sedentary group, mean adjusted BMD was 2.2% greater for the active and 6.0% greater for the very-active group (both p<0.001). For women, mean adjusted BMD for the active group did not differ to the sedentary group (p=0.520), however, the very-active group had a mean adjusted BMD that was 3.7% greater than the sedentary group (p=0.004).

Discussion

For men, higher levels of general physical activity were dose-dependently associated with greater BMD at the hip, a weight-bearing site, across adulthood. The pattern for women was less clear; however, a very-active lifestyle was consistently associated with higher BMD in comparison to a sedentary lifestyle. 

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