Effects of walking on bone quality as determined by ultrasound in the elderly.

In the present study, measurements of broadband ultrasound attenuation (BUA) were used as indications of bone quality in elderly residents of an old people's home. To investigate the possibility of using number of steps walked as an indicator of the role played by exercise on bone quality, we studied the relationship between BUA and the number of steps, taken as a measure of the number of impacts against the ground placing a direct mechanical stress on the bones. The subjects were 59 healthy elderly women with a mean age of 78+/-8 years who had no impairments in walking or daily life. A statistical analysis of the relationship between age, number of steps, BUA, stride length, and walking speed revealed that number of steps and BUA declined with age, and that BUA increased with a greater number of steps. Among other factors, age was found to be negatively correlated with weight (r= -0.343, P<0.01), BUA (r=-0.542, P<0.001), total number of steps (r= -0.524, P<0.001) and past exercise habits (r=-0.425, P<0.001). There were positive correlations between BUA and total number of steps (r=0.606, P<0.001), walking speed (r=0.460, P<0.001), stride length (r=0.373, P<0.01) and past exercise habits (r=0.429, P<0.001). These results show that the benefit to bone quality increases the more a person walks in daily life. The above demonstrates that degree of walking activity is positively correlated to bone quality among the elderly. These results also suggest that, when investigating the relationship between exercise and bone quality, one should look not only at distance and walking speed, but also number of steps as the number of impacts against the ground that place a direct mechanical stress on the bones. This may prove to be a useful indicator of bone quality in future use.