Temporal and spatial muscle synergy features and its neural origins during sit-to-stand and stand-to-sit tasks

Sit-to-stand (STS) and stand-to-sit (StandTS) play a vital role in our daily lives. These two transitional motions are considered crucial for independent living. Many people with neurological disorders that lack neuromuscular control lose the ability to perform the transition tasks normally. Several muscles act together to achieve these motions and the inability to perform these daily life tasks, therefore, present the need to understand why they are important and what is the role of muscle synergy in the performance of such tasks. Reduced number of synergies have been found in populations with neurological disorders and the differences in the number of muscle synergies reflect descending neural pathway disruptions and present a correlation with motor deficits. Therefore, this review aims to understand the importance of these two transitional motions and muscle synergy extensively to help develop targeted interventions for healthy and clinical populations.