LaPorta Krum, L., Smith, S., Sanborn, C., Thompson, M.; Texas Woman’s University, Dallas, TX and University of Nevada, Las Vegas, Las Vegas, NV. laura.laporta@ccmail.nevada.edu.

The effects of walking exercise on bone mineral density (BMD) in postmenopausal women with low hip BMD have demonstrated variable results. PURPOSE: The purposes of this study were to: (a) examine step length, gait velocity, and vertical ground reaction forces (GRF) of women with normal and low hip BMD, and (b) determine whether GRF of women with low hip BMD could be increased by altering gait parameters. SUBJECTS: Fifty-two postmenopausal women participated in this study and were divided into two groups: Normal (n = 24) and Low Bone Mass (n = 28) based on BMD T- scores of the proximal femur. METHODS: Step length, gait velocity, and GRF were recorded during normal walking for all subjects. Women with low BMD (n = 28) also participated in three modified walking conditions in which step length and/or gait velocity was increased. ANALYSIS: Hotelling’s T² covaried with weight tested for differences between the groups in step length, gait velocity, and GRF. Correlation and regression analyses were used to determine the relationship between gait variables and BMD. Repeated measures ANOVA was used to test for differences between GRF produced during the normal and modified walking conditions in women with low BMD. RESULTS: Women with low BMD had longer step lengths (F_{(1, 52)} = 11.48, p < .001) and increased gait velocity (F_{(1, 52)} = 4.15, p < .05) than women with normal hip BMD. Lower GRF during walking was also related to lower BMD at the femoral neck (r = .44, p < .01), and total hip (r = .46, p < .01). Walking with a 20% increase in gait velocity independently or in combination with a 10% increase in step length increased GRF compared to normal walking (F_(1,28) = 33.90, p < .001). CONCLUSIONS: Walking exercises using increased gait velocity alone or in combination with increased step length increases ground reaction forces, which via Wolff’s Law could increase hip BMD. Future studies investigating the effect of modified step length and gait velocity on BMD of the hip during prolonged walking exercise are indicated to determine whether walking is a beneficial form of exercise to enhance BMD and reduce the risk of hip fracture. FUNDING SOURCE: None.

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