Objectives It is unclear whether gait speed can be used to predict bone status or to diagnose osteopenia or osteoporosis. The aim of our study was to determine whether the measurement of physical performance predicts bone strength in community-dwelling postmenopausal Japanese women. Methods We measured speed of sound (SOS), weight bearing index (WBI), maximum or usual gait speed, step length of each gait, single leg balance time with or without eyes closed, and grip strength among 1,061 postmenopausal women (mean age ± standard deviation 68 ± 8 years). Results After adjustments for age and body mass index, SOS was associated with maximum or usual gait speed and with step length during maximum speed gait, but not with WBI, grip strength, single-leg balance time with or without eyes closed, or step-length time during usual gait speed. When subjects were divided into quartile groups based on WBI (a marker of lower extremity strength), significant associations between usual or maximum gait speed and SOS were found only in the lowest and second lowest groups (first and second quartiles). Finally, analysis of sensitivity and specificity at various cut-off points of maximum gait speed to predict decreased SOS showed relatively high specificity compared with the corresponding sensitivity among those with low gait speed. Conclusions Maximum gait speed together with WBI may be a useful and specific test to predict bone status in postmenopausal older women.

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.

To understand the physical and other factors related to walking among the elderly residents of a Care House for the aged, the total number of steps walked were measured over a period of I week (Nov. 6-12. 1994) for 67 female residents (mean age 79 + 1 years). In addition, walking speed, stride length, and the time to climb 15 steps (stair-climbing time) were measured. To understand the indirect factors such as balance and agility that may control walking, tests were conducted on the subjects' ability to stand on one leg with eyes open and closed, and jumping reaction time. Results showed a negative correlation between total number of steps and age (r=-0.543, P< 0.01), jumping reaction time (r=-0.258, p<0.05) and stair-climbing time (r=-0.501, P< 0.01). However, a positive correlation was found between total number of steps and stride length (r=0.408, P< 0.01), walking speed (r=0.419, P< 0.01), self-rated health (r= 0.390, P< 0.05) and standing on one leg with eyes closed (r=0.258, P< 0.05). The total number of steps walked and physical factors, particularly physique and balance, were also closely related. The above suggests that a walking habit among elderly persons helps to slow the decline in physical strength, which is necessary to prevent falls. It is also reflected in the person's awareness of health and may increase the opportunities for leading an active daily life.

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