A popular term that is tossed around among sportscasters and fitness professionals is "muscle memory." The basic premises behind muscle memory is the more you practice a skill, the better you become at it because the muscle "remembers" what to do. There is no doubt that proper practice yields improvement in performance, strength, coordination, etc. However, these changes are not due to muscle memory. There is no memory structure within the muscle itself, therefore, the muscle cannot remember or forget to do things. Every single muscle fiber is connected to the nervous system by the way of a motor unit. In order for a muscle to fire or contract, a signal must be sent to the fibers from the nervous system. The "memory" part is in the nervous system, and more specifically, in the brain. If you remember the first time you attempted to hit a baseball, shoot a basketball, ride a bike, etc., you were probably clumsy, uncoordinated, and had little success. Over time, you probably saw improvement. When we perform a skill we have little to no experience with, the nervous system does not know which muscles to recruit (activate), how many muscles to recruit, how frequently to recruit the muscles, and when to turn the muscles off. As we practice the skill, the nervous system begins to learn and remember, and recruits only the muscles needed to perform the skill, and at the right frequency and intensity. The nervous system also learns to turn off muscles that are not needed to perform the skill and would hinder performance. So, the theory of muscle memory is actually a complex process that involves both the nervous system and the muscular system. But, there is no memory structure within muscle, so the term muscle memory is fiction.
