Recruitment frequency of gastrocnemius lateralis in people with Parkinson’s disease during locomotion

Abstract

Motor impairments are one of the most disabling symptoms related to Parkinson's disease (PD) and negatively affect quality of life [1]. Recently aberrant motor control in this population was investigated by means of surface electromyography (sEMG) in terms of timing of muscle activation [2]. Yet, insights on the recruitment frequency during gait are still lacking. Therefore, this study aims to characterize muscle recruitment frequency in PD with respect to healthy controls during walking. Twenty-five people with PD (age = 64 ± 10 years; BMI =26±3) and ten able bodied subjects (age = 62±6 years; BMI =28±3) were included and underwent sEMG while walking on a 8 m walkaway at BiomovLab (University of Padova, Italy). Three bilateral strides per subject were considered (105 strides in total). Electrical activity of gastrocnemius lateralis (GL) was recorded. To identify onset and offset of the muscle activation, the wavelet-based algorithm presented in [3] was adopted. Then, each signal was digitized in accordance with the detected activation timing (0 = no activation detected, 1 = activation detected) and used to provide activation maps [4] for both the assessed populations. The following Fig. 1 reports the activation map of GL activation for PD and control populations in function of the number of subjects of the specific population where muscular activity is observed. Horizontal bars are grey-level coded, according to the number of subjects of the population where a GL activity is detected; black = activity detected in all subjects, white = activity never detected. PD population presents a very frequent GL activity (close to 100%) between 35% and 55% of the gait cycle, as expected. A relatively poor activity is detected in the other gait cycle phases. Although GL in PD is more frequently recruited in the same gait cycle phase of controls (≈ 70%), healthy subjects displayed more homogeneous GL activity over the whole gait cycle. These outcomes seem to suggest that PD patients are characterized by a reduced ability to adapt to gait-related needs compared to age- matched control subjects.