Protocol for bradykinesia characterization through the relationship between the movement initiation and the termination of the preceding movement

Bradykinesia is one of the motor symptoms of Parkinson's Disease (PD) and it is defined as the slowness in movement. This symptom is also related to two others: akinesia (the difficulty to initiate a movement) and hypokinesia (the decrease in the movement amplitude). One feature of PD is the difficulty to initiate volitional movement. In the literature, it has been raised the question rather this difficulty is due to prejudice at the end of the preceding movement/posture or to the impairment at the beginning of a new movement. Seeking deeper research in the literature about the relationship between the difficulty of initiating volitional movement and the impaired completion of the preceding movement, a literature review has shown a gap in this subject, moreover when it is referred to tasks involving multi-joint movements. Therefore, this work aims to be the starting point to elucidate the mentioned topics, presenting a protocol for the characterization of bradykinesia in subjects with PD through the evaluation of the relationship between the movement initiation and the termination of preceding movement in upper limbs while performing multi-joint tasks. This protocol has been designed based on a literature review and it consists of the following steps: electromyographic acquisition including temporal and inertial variables, description of the tasks involving multi-joint movement to be performed, design for tasks performance, and data analysis. Finally, this experimental protocol will be applied to healthy subjects and patients diagnosed with PD. With the application of this protocol, it is expected to better comprehend the factors behind the difficulty of initiating volitional movements, as well as to identify muscular and kinematic patterns related to bradykinesia. The knowledge of this relationship will support future studies to develop and seek technology/intervention that help people with PD.