Correlates of thigh muscle index with physical performance in ambulatory geriatric patients

Abstract

Objective: 1) to validate the correlation between the estimated dominant thigh muscle volume using anthropometric measurements and the physical performance of lower limbs in elderly adults at ambulatory clinics; 2) to examine the association between dominant thigh muscle index and frailty. Design: Longitudinal observational study. Setting: Outpatients at family or geriatric medicine clinics. Participants: One hundred forty-eight elderly adults aged 65-90. Measurements: The anthropometric measurements (including weight and thigh circumference), appendicular skeletal muscle mass by bioelectrical impendence analysis (BIA), quadriceps muscle strength, physical performance (including timed Up & Go test, 5-meter walking time, and handgrip strength) were examined at baseline and 1-year follow-up with the Fried Frailty Index evaluated concurrently. Results: The estimated dominant thigh muscle volume was correlated positively with quadriceps muscle strength and the predicted appendicular skeletal muscle mass but negatively with physical performance (timed Up&Go and 5m walking time) (p≦0.01). Dominant thigh muscle index (quadriceps muscle strength per estimated thigh muscle volume*1000 of the dominant leg) was marginally different between genders (p=0.06). Additionally, older age, weaker quadriceps muscle strength, lower dominant thigh muscle index, and longer time for TUG (timed Up & Go) test were associated with frailty status (all p-values < 0.05). Dominant thigh muscle index was an independent and protective factor associated with frailty after age adjustment. Conclusion: Using the equation with anthropometric measurements to estimate thigh muscle volume is a simple and noninvasive method. Moreover, dominant thigh muscle index helps detect frailty at an early stage and minimize the impacts of gender difference on frailty.