Effect of exercise on extraskeletal risk factors for hip fractures in elderly women with low BMD:: A population-based randomized controlled trial

Introduction: Evidence on the effect of exercise on extraskeletal risk factors for hip fractures comes mainly from studies in voluntary low-risk women, and no population-based, long-term interventions have been performed in elderly women with low bone mass. The aim of this study was to determine the effect of long-term weight-bearing exercise on balance, muscle strength, and gait in elderly women at risk for fractures on the basis of a low baseline BMD. Materials and Methods: A birth cohort of 1690 women 70-73 years of age were invited to the radius and hip BMD measurements; 96 women were excluded because of medical reasons; 160 women with radius and hip BMD values of > 2 SD below the reference value were included in the trial. The participants were randomly assigned to 30 months of impact, balancing, and strengthening exercises or to no intervention. Main outcome measures were body sway length and leg strength at month 30. Secondary endpoints included gait speed, endurance, and grip strength. Outcomes were assessed at 0, 12, 24, and 30 months using blinded operators. Repeated-measures ANOVA was used to determine statistical significance. The analyses were performed on an intention-to-treat basis. Results: Body sway increased more in the control group than in the exercise group over time (time-group interaction, p < 0.001). Leg strength improved in the exercise group and decreased in the control group (interaction, p < 0.001). A significant time-group interaction (p < 0.001) in favor of the exercise group was found on the following secondary endpoints: the timed up and go test score, walking speed, and distance walked in 2 minutes. Conclusions: Weight-bearing exercise is an effective way of modifying extraskeletal risk factors for fractures in elderly women.