Developing new intermuscular coordination patterns through an electromyographic signal-guided training in the upper...

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• Muscle synergies represent coordinated intermuscular activation patterns crucial for neuromuscular control and learning.
• Existing research has not definitively established whether adults can intentionally alter or create new muscle synergies through short-term motor training.
• This study investigated the potential for expanding the repertoire of muscle synergies in the upper extremity (UE) using a novel exercise approach.

Purpose of the Study:

• To determine the feasibility of developing new muscle synergies in healthy adults.
• To assess if a short-term, isometric, electromyography (EMG)-guided exercise protocol can expand intermuscular coordination patterns.
• To evaluate the impact of this training on motor control and the conservation of existing synergies.

Main Methods:

• Ten participants underwent a six-week isometric training program focused on independent control of co-activated elbow flexor muscles.
• Electromyography (EMG) signals from 12 UE muscles were recorded during untrained tasks to identify muscle synergies using non-negative matrix factorization.
• Training task performance and individual muscle activity in time and frequency domains were quantified.

Main Results:

• Participants demonstrated the ability to utilize newly developed muscle synergies for untrained tasks within two weeks.
• Previously established muscle synergies remained conserved throughout the training period.
• Improved neuromotor control was observed, indicated by enhanced muscle activation ratios, target matching, and reduced task completion times.

Conclusions:

• The isometric EMG-guided protocol effectively expands the repertoire of muscle synergies in healthy adults within a short timeframe.
• This approach enhances motor control by facilitating the development of novel muscle coordination patterns.
• The protocol shows promise as a neurorehabilitation tool for addressing motor deficits linked to abnormal intermuscular coordination.