Effect of handedness on muscle synergies during upper limb planar movements

Handedness is a prominent but poorly understood aspect of human motor performances. Despite it is generally accepted that it results from differences in the neural control of the arm, the mechanisms at the origin of the side-difference in motor performances are still unknown. In this work, we propose to deepen this aspect by investigating muscle synergies organization. We obtained muscle synergies through the factorization of the superficial electromyographical (EMG) activity related to fifteen upper limb muscles in the dominant and non-dominant side of 5 healthy young right and left dominant subjects, while executing planar wide and tight circular trajectories. Our preliminary results showed that right and left handed subjects performed the circular trajectories with a different muscle organization. Moreover, a task-related side-difference in muscle synergies was observed. Further investigations in a larger cohort of individuals are necessary to determine the neural mechanisms generating the differences in number and organization of muscle synergies between left and right handed individuals.