*Corresponding author:Wan X Yao, Department of Kinesiology, Health, & Nutrition College of Education & Human Development, The University of Texas at San Antonio, San Antonio, USA
Received: July 23, 2018; Published: September 10, 2018
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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 [1,2] or stops [3-5]. 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.
Keywords: Motor Unit Recruitment; Discharge Rate; Motor Unit Synchronization; Force Variability