Habitual physical activity and bone mineral density in postmenopausal women in England

Background Reduced levels of physical activity have been found to be associ ated with an increased risk of osteoporotic fracture in a number of epidemi ological studies, and intervention studies have shown beneficial effects of exercise regimes on bone mineral density. It is not yet established, howev er, which specific forms of customary physical activity are most strongly a ssociated with bone mineral density in postmenopausal women. Methods A cross-sectional study was conducted in 580 postmenopausal women, aged 45-61 years, resident in Nottingham, England. The participants complet ed a detailed interviewer-administered activity questionnaire. Physical act ivity was assessed as total hours of participation per week in activities i ncluding housework, walking, gardening and sports. Stair-climbing and self- reported walking pace were also reported. Bone mineral density measurements were made using dual energy x-ray absorptiometry, measurements at five sit es were used in analysis. Results The strongest associations between the activity measures and bone m ineral density were for stair-climbing and walking pace, which both gave st atistically significant positive associations at the trochanter hip site an d the whole body. In women reporting a fairly brisk or fast walking pace, b one mineral density at the proximal femur was also significantly and positi vely associated with the frequency of walking at least a mile. There were n o significant associations with aggregate measures of total customary physi cal activity. Conclusions This study has identified two forms of physical activity, namel y stair-climbing and brisk walking which are associated with increased bone mineral density at the hip and whole body in postmenopausal women. Both ar e feasible forms of activity for promoting to middle-aged women.