Threshold of lower body muscular strength necessary to perform ADL independently in community-dwelling older adults

Abstract

OBJECTIVE: To determine the thresholds of lower extremity muscle strength below which performing activities of daily living (ADL) is impaired in older adults. DESIGN: Cross-sectional. SETTING: Community. SUBJECTS: Forty-nine older adults (81-89 years) were divided into an independent group (n = 25) who needed no assistance and a dependent group (n = 24) who needed assistance to perform ADL. INTERVENTIONS: Not applicable. MAIN MEASURES: Functional independence measures to determine level of disability and muscular strength of hip flexors, hip extensors, knee flexors, knee extensors and ankle dorsiflexors assessed by a hand-held dynamometer (HHD). Muscle groups were tested separately for each leg and values were averaged for the two legs. A ratio of maximal muscular strength to body weight was calculated by dividing the muscular strength (N) by body weight (kg). RESULTS: Muscular strength thresholds to perform ADL independently were 2.3 N/kg for hip flexors, 1.7 N/kg for hip extensors, 0.7 N/kg for knee flexors, 2.8 N/kg for knee extensors and 2.8 N/kg for ankle dorsiflexors. CONCLUSION: The thresholds of lower extremity muscle strength below which assistance is required to perform ADL in community-dwelling older adults were identified. Furthermore, results indicate that the muscular strength of hip extensors is more important in performing ADL than other muscles of the lower extremities.