Relationships among impairments in lower-extremity strength and power, functional limitations, and disability in older adults

Background and Purpose During the aging process, older adults may experience a loss of strength and power, which then may lead to functional limitations and disability. The purpose of this study was to examine how impairments in lower-extremity strength and power are related to functional limitations and disability in community-dwelling older adults. Subjects Thirty older adults (age [(X) over bar +/- SD], 77.3 +/- 7.0 years; 25 women and 5 men) with mild to moderate functional limitations participated in this study. Methods Lower-extremity strength, peak power, power at a low relative intensity, and power at a high relative intensity were measured with a pneumatic resistance leg press. Functional limitations and disability were assessed with the Short Physical Performance Battery (SPPB), the Six-Minute Walk Test (SMWT), and the Late Life Function and Disability Instrument (LLFDI). Results All measures of strength and power were related to functional limitations. Peak power demonstrated the strongest relationships with SMWT, the SPPB gait speed subscale, and the LLFDI functional limitation component. Power at a high relative intensity demonstrated the strongest relationships to the SPPB total score and the SPPB sit-to-stand subscale score. All measures of strength and power were indirectly related to the LLFDI disability component. Discussion and Conclusion Older adults should focus on increasing and maintaining lower-extremity strength and power across a range of intensities in order to decrease functional limitations and disability.