Muscle memory, despite what the name implies, does not refer to memory stored in the muscles. The memories, of course, are stored in the brain and they serve as a cache of often enacted tasks by the muscles. It can be classified as a form of procedural memory. It explains how you can be very good at doing something through repetition. Similarly, it also explains how you can be terrible at the same thing.
If you constantly practice the same song on the piano over and over, the idea is that you are going to get better. As the old adage says, “Practice makes perfect”. As you do something more and more, you build up procedural memory and your brain instructs your muscles to carry out the task. Muscle memory, however, does not care whether you are doing good or bad at whatever it is you are doing. This means if you always make mistakes while playing a certain song on the piano, then you are going to make the same mistakes repeatedly. You can say that you might be wasting time just practicing how to be bad. But what’s more frustrating is that you didnít have to fail in the first place. When you commit the same mistakes over and over again, muscle memory kicks in and you do those mistakes inevitably. That makes the same mistakes harder to correct later on. This is where the saying, “You can’t teach an old dog new tricks”, comes in.
The secret to developing good muscle memories is to put emphasis on the quality of the quantity. You may have probably read from Malcolm Gladwell’s book “Outliers”, that a person needs 10,000 hours to be great at doing a certain thing. This can be true assuming that you do the right things while practicing. But if you put very little attention to the details, all you might be doing is building procedural memory the wrong way. You will just be good at repeating the same mistakes. This is why it helps to practice at a slow pace at first. Learning how to play a song on the piano, for instance, must not be rushed. You can break up the song into multiple parts and master each one before proceeding to the next. Practice the parts slowly until you can play them perfectly and then itís time to speed things up a bit. In general, terms, when you want to learn something, take it little by little and work your way up gradually. Take frequent breaks. Stay patient. The more you rush, the more you are likely to develop muscle memories that are hard to reverse.