Identification of frailty is essential to understanding and mitigating age-related physical impairments. Previous studies have indicated that frailty phenotype can be identified through electromyography (EMG) when collected over the course of an 8-h day. However, long duration recordings challenge both the clinician and the older adults but activities of daily living that are most sensitive to changes in frailty status are currently unknown. The purpose of this study was to determine if muscle activity recorded during specific task, or groups of tasks, could be used to correctly classify middle-aged, non-frail, pre-frail, and frail older adult pheonotypes. Fifteen middle-aged (49±5years) and 76 older adults (77±8years) participated. Older adults were categorized as non-frail (n=49), pre-frail (n=20), or frail (n=7) using self-selected normal gait speed and a modified frailty index score. Bursts and gaps in EMG of the biceps brachii, triceps brachii, vastus lateralis, and biceps femoris were measured bilaterally during nine different functional tasks.
Relatively high levels of success for frailty group classification (near 90%) can be achieved from EMG. Bursts were more frequent and gaps fewer in frail compared with middle-aged and non-frail adults. The numbers of gaps and muscle quiescence in the upper limbs were particularly important. Changes in muscle activity offer predictive value in identifying frailty phenotype. Completing functional tasks (rising from the floor, toilet and chair) while undergoing EMG assessment can contribute to the identification of differences in frailty phenotype among older adults.