Relationship between knee extension force and stand-up performance in community-dwelling elderly women

Objective: To describe the relationship between knee extension force and st and-up performance. Design: Prospective, cross-sectional, descriptive, and correlational. Setting: Community. Participants: Fifty-five community-dwelling women 60 or more years old. Interventions: Information pertaining to stand-up performance was gathered via structured questions. The time to complete 1 sit-to-stand from a bench of known height (16in) was obtained in conjunction with subjects' ratings o f perceived exertion (RPEs) relative to the task. Bilateral lower extremity knee extension strength was measured with a hand-held dynamometer and norm alized against body weight. Main Outcome Measures: Total knee extension forces (raw and body-weight nor malized values) generated by each subject were correlated with 3 measures o f stand-up performance. Results: Low to moderate correlations (r = -.323 to -.526) were found betwe en knee extension forces and the stand-up performance measures of bench sta nd time and stand-up difficulties. Normalized knee extension force had a hi gher correlation than raw knee extension force with stand-up difficulties a nd RPE. Correlations were higher when the curvilinear nature of the relatio nship was taken into account. The highest correlation was between normalize d knee extension force and the RPE associated with the bench stand task (r = -.767). Conclusion: Knee extension force offers an important but incomplete explana tion of stand-up performance from low surfaces by elderly women. Interventi ons leading to increased knee extension force may improve stand-up performa nce.