Associations of daily walking steps with calcaneal ultrasound parameters and a bone resorption marker in elderly Japanese women.

Quantitative ultrasound (QUS) parameters of the calcaneus and bone resorption markers predict osteoporotic fractures. High levels of physical activity have positive effects on bone health. The purpose of this cross-sectional study was to investigate the effects of daily walking activity (number of steps taken), as an outcome of physical activity, on QUS parameters of the calcaneus and urinary deoxypyridinoline (DPD) in elderly Japanese women. The subjects were 113 postmenopausal women aged 60-85 years. The speed of sound (SOS), broadband ultrasound attenuation (BUA), and the stiffness index (Stiffness) of the calcaneus were measured with A-1000 (GE-Lunar, USA). Spot urine samples were collected between 09:00 and 10:00, and the levels of urinary DPD were measured. The subjects were instructed to wear a pedometer during waking hours for 7 consecutive days. In univariate analyses, steps/day significantly decreased with aging (r=-0.306, p<0.001). Steps/day showed significant positive correlations with SOS (r=0.252, p<0.01) and Stiffness (r=0.258, p<0.01). There was a significant decrease in DPD with steps/day (r=-0.262, p<0.01). These effects of walking on QUS parameters and DPD remained significant after adjustment for confounding factors by multiple regression analyses. We conclude that high levels of walking activity may be effective in both maintaining the levels of QUS parameters and reducing bone resorption, and hence preserve bone health in elderly women.