Investigating the synergies of coordinated activities of upper limb muscles during flexion/extension motion

The human central nervous system (CNS) controls coordinated muscles that is known as muscle synergies instead of controlling each muscle separately. The redundancy of musculoskeletal structure to perform specific motion is the reason of applying muscle synergies to reduce the dimensionality of motor control. The goal of this work is to study the human upper limbs muscles coordination and indicate the performance of motor control to describe upper limb movement and to obtain the number of synergies required for the motion and realize the Timing of muscle activity with respect to the phases of movement. In this study, the shoulder flexion/extension motion is considered to evaluate the upper limbs muscle function. The upper limbs muscles electromyography data (EMG) is extracted by surface markers. As the result, three number of synergies was extracted based on the variance accounted for (VAF) index to describe how the human motor control is managed by the central nervous system (CNS). Knowing the dominant muscles in each synergy causes to design the rehabilitation exercises more effectively and design rehabilitation orthosis more precisely.