Daily electromyography in females with Parkinson's disease: A potential indicator of frailty

Females with Parkinson's disease (PD) are at increased risk for frailty, yet are often excluded from frailty studies. Daily electromyography (EMG) recordings of muscle activity can dissociate stages of frailty and indicate functional decline in non-neurological conditions. The purpose of this investigation was to determine whether muscle activity can be used to identify frailty phenotypes in females with PD. EMG during a typical 6.5-h day was examined in biceps brachii, triceps brachii, vastus lateralis and biceps femoris on less-affected PD side. Muscle activity was quantified through burst (>2% maximum exertion, >0.1 s) and gap characteristics (<1% maximum exertion, >0.1 s). Differences across frailty phenotype (nonfrail, prefrail, frail) and muscle (biceps brachii, BB; triceps brachii, TB; vastus lateralis, VL; biceps femoris, BF) were evaluated with a 2-way repeated measure ANOVA for each burst/gap characteristic. Thirteen right-handed females (mean = 67 ± 8 years) were classified as nonfrail (n = 4), prefrail (n = 6), and frail (n = 3) according to the Cardiovascular Health Study frailty index (CHSfi). Frail females had 73% decreased gaps and 48% increased burst duration compared with nonfrail. Decreased gaps may be interpreted as reduced muscle recovery time, which may result in earlier onset fatigue and eventually culminating in frailty. Longer burst durations suggest more muscle activity is required to initiate movement leading to slower movement time in frail females with PD. This is the first study to use EMG to dissociate frailty phenotypes in females with PD during routine daily activities and provides insight into how PD-associated motor declines contributes to frailty and functional decline.