"Muscle memory" has always been synonymous with "sports learning" and is a procedural memory, which involves consolidating specific sports tasks into memory through repetition. When an action is repeated for a long time, it creates a long-term muscle memory for this task, and finally makes it go on unconsciously. This process reduces the need for attention and creates the maximum efficiency of the motor and memory system. Examples of muscle memory can be found in many daily activities, such as riding a bicycle, typing on a keyboard, entering personal identification numbers, playing musical instruments, playing poker and martial arts, and even dancing. These activities will become automatic and improve with practice. This is what we often say "Practice makes perfect"!

The main brain area involved in sports learning is cerebellum. Some motor learning models related to cerebellum, especially Marr-Albus model, proposed a single plasticity mechanism, which involved the long-term inhibition of synaptic projection from cerebral cortex to Purkinje cells in cerebellum (LTD). The modification of these synaptic activities regulates the input and output of sports, which is the key to sports learning. However, contradictory evidence shows that a single plasticity mechanism is not enough, and multiple plasticity mechanisms are needed to explain the storage of motor memory over time.

Regardless of its mechanism, the research on cerebellar-dependent motor tasks shows that the plasticity of cerebral cortex is very important for motor learning, even if it is not necessarily used for memory. Basal ganglion also plays an important role in memory and learning, especially in stimulus-response connection and habit formation. When learning sports tasks, the basal ganglia-cerebellum connection is considered to increase with time.

In the first paragraph of the article "The Power of Habit", the author uses an example of an amnesiac patient to illustrate that some behaviors are beyond the control of the brain. The old man named Eugene lost his memory because of illness. He won't remember what he said a few minutes ago, but scientists were surprised to find that although Eugene couldn't remember what happened a few minutes ago, he got up every morning to get something to eat in the refrigerator, and he took his kitchen to make breakfast and go to the toilet every day.

But when scientists asked Eugene to draw a road map from the bedroom to the kitchen, Eugene couldn't draw it. Even once Eugene went out for a walk and came back, but he couldn't even draw a map from the bedroom to the kitchen. How can he find a home a few blocks away? For scientists, this is incredible. After a lot of research and experiments, it is finally concluded that these behaviors of Eugene are all habits formed by the brain before, so that Eugene can clearly remember the way home when he has amnesia.