Hip extension strength: Description and validity of a new procedure applied to older women

OBJECTIVE: We sought to: 1) describe a new procedure for measuring hip extension strength and 2) examine the convergent and known-groups validity of measurements obtained using the procedure. METHOD: Forty women (72–98 years) volunteered for this cross-sectional, observational study of muscle strength and mobility. Hip extension strength as well as hip flexion and knee extension and flexion strengths were measured using a hand-held dynamometer (HHD). Hip extension strength was measured while participants were supine and the HHD was positioned under their slightly elevated distal leg. Participants were dichotomized as independent or dependent in sit-to-stand and walking. RESULTS: Hip extension strength was measured without difficulty or untoward effects. Relative to other ipsilateral measures of hip and knee strength, hip extension strength was found to correlate significantly (r = 0.345–0.584), to be internally consistent (alpha = 0.785 and 0.751), and to load strongly (0.733 and 0.705) on a common construct-lower limb strength. Hip extension strength (left+ right/body weight) discriminated (albeit weakly) between known groups, that is, participants who were dependent versus independent in sit-to-stand and walking. CONCLUSION: Based on these findings we recommend this procedure for measuring hip extension strength in older adults.