Motor-Unit Recruitment Plays an Important Role in Determining the Relationship Between Muscle Force and Force Variability

Literature shows that force variability increases when force levels increase. However, this constant increase occurs only to a certain point (e.g., at around 50% of maximum voluntary contraction (MVC) and 80% MVC). After this point, the increase of force variability either slows The potential underlying mechanism accounting for the changing rate of increase in force variability is discussed in this brief review. It concludes that among several factors, motor-unit recruitment appears to be the most important factor in determining the relationship between force and force variability although both motor unit discharge rate variability and synchronization have a significant impact on force variability as well.