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

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.