Modifications of muscle synergies during adaptation to upper limb divergent force fields in healthy subjects

It is well known that people exposed to a robot-generated force field disturbing arm motion, are able to recover their unperturbed kinematic patterns. It has been also reported that muscle synergies undergoing the activation of many muscle groups are strongly consistent apart from external (e.g., reaching movements in the frontal or in the sagittal plane) or internal (e.g., severity and location of a cerebrovascular accident) constraints. Here, we investigated whether and how muscle synergies underlying the activation of upper limb related motor tasks, can be modified due to a divergent force field exposure. Results showed that muscle synergies can be significantly modified during the ongoing of the training. This open up new possibilities for the development of more effective neuro-rehabilitation protocols.