Muscle memory can best be described as a type of movement with which the muscles become familiar over time. For instance, newborns don’t have muscle memory for activities like crawling, scooting or walking. The only way for the muscles to become accustomed to these activities is for the baby to learn how to do these things and then practice them with a great deal of trial and error. Gradually, as the baby becomes a skilled walker, he falls less, is able to balance, and finally is able to incorporate other activities into his life such as running.
Although the precise mechanism is unknown, what is theorized is that anyone learning a new activity, or practicing an old one has significant brain activity during this time. The walking child is gradually building neural pathways that will give the muscles a sense of memory. In other words, even without thinking, the child is soon able to walk, and the muscles are completely accustomed to this process. The child doesn’t have to tell the body to walk; the body just knows how to do it, largely because neurons communicate with the muscles and say, “walk now.”
Muscle memory thus becomes an unconscious process. The muscles grow accustomed to certain types of movement. This is extremely important in different types of training for sports. The more often you do a certain activity, the more likely you are to do it as needed, when needed. If you’ve kicked thousands of field goals, exercise physiologists assume that the likelihood of being able to kick one during an American football game is pretty good through this memory. You don’t have to think, “I need to make this kick.” Your body already knows how to do it.
This is one of the reasons that with many activities that involve the body’s muscles, like playing an instrument, learning appropriate technique is always stressed. You want your muscle memory to reflect the correct way to do things, not the incorrect way. Your muscles can actually play against you if you’ve constantly been practicing something the wrong way.
Music teachers often make this argument. It’s a lot harder to teach someone who’s been playing an instrument for a few years because the first step is breaking them of all the bad habits they’ve acquired, which are now part of the muscle memory. Similarly, if you learn to bat, throw, kick or pitch wrong, the memory has to be overcome, and new neural pathways formed to be a better athlete.
Most top level athletes and performers in a variety of fields believe that muscle memory is best developed when the same activities are practiced over and over again, with any corrections of form that are needed. Continual practice may mean you can make that perfect golf swing every single time (or almost), or hit a high note every time if you’re a singer.
It does appear though, that despite practice, attitude can interfere with the process. Nerves can lead to clenched muscles that can’t quite perform, as they would probably do if you weren’t thinking about it. A sense of being unable to perform as you would wish may also affect the muscles. The processes are still complex, and the “confidence factor” needs to be taken into account in future studies on muscle memory.