Effect of daily walking steps on ultrasound parameters of the calcaneus in elderly Japanese women.

In this cross-sectional study, we investigated the effect of daily walking steps on ultrasound parameters of the calcaneus in elderly Japanese women. The subjects were 143 community-dwelling elderly women aged 61-87 years (mean age 71.4+/-5.5 years). The speed of sound (SOS), broadband ultrasound attenuation (BUA) and the stiffness index (Stiffness) of the calcaneus were measured. Walking steps were recorded using a pedometer for 7 consecutive days as an outcome measure of physical activity. In univariate analyses, steps/day significantly decreased with aging. SOS, BUA and Stiffness showed negative correlations with age and positive correlations with weight. Linear relationships were not seen between any of the ultrasound parameters and daily walking steps. Then, the ultrasound parameters were adjusted for age and/or weight using multiple regression models, and the relationships between the adjusted ultrasound measurements and walking steps were examined using quadratic regression models. Walking activity up to approximately 12,000 steps/day was positively associated with the adjusted ultrasound measurements, above which additional walking steps had no positive effect. We conclude that daily walking steps may be suitable for evaluating the relationship between ultrasound parameters and physical activity in elderly women, but further research is needed to confirm the effect of daily walking steps on the rate of bone loss.