Motor speed and lower extremity strength as predictors of fall-related bone fractures in elderly individuals

Abstract

The purpose of this prospective population-based study was to examine the combined effects of motor speed and knee extension strength on risk of fall-related bone fractures in elderly individuals over a 10-year period. Participants were 307 men and women aged 75 or 80 years at baseline, who visited the research laboratory at the University of Jyväskylä, Finland. Multi-choice motor speed tests and maximal isometric knee extension strength tests were carried out at baseline. Information on fractures was collected from hospital and health center records. The presence of impairment was defined as a score in the lowest tertile of sex- and age-stratified distribution of results in each test. During the 10-year period, 93 participants had at least one fracture. In Cox proportional hazards models for motor speed and knee extension strength, the risk of fracture was almost double in the lowest vs the highest tertile of each test score. For those in the poorest speed and strength tertiles compared with the best speed and strength tertiles, the relative risk of fracture adjusted for age, sex and bone mineral density was 4.69 (95% confidence interval 1.72-12.81). Increased risk of fracture was observed for those with either slow motor speed or poor lower extremity strength; however, a combination of these impairments increased the fracture risk significantly when compared with those with no impairments. A co-impairment approach may prove useful in gaining better understanding of the risk of fall-related bone fractures and the development of effective interventions.