I answered this question that was posed on line
What process does a swimmer need to follow to make a meaningful change in his or her swimming stroke? What’s the expected timeframe for change, and is the timeframe different depending on what aspect you’re trying to change, e.g., does it take longer to change something involving the head… or the body… or the arms… or the feet?
Before I can answer some of the questions I need to cover a few global items that affect everything. Also this is a cliff note version since to really cover this in depth would require quite a number of pages of thoughts.
We all think of the muscles as being the prime movers with regards to mechanics, but cut to the quick, what makes us move is that chain of neurons all involved the process of dictating the exact power and timing of the working muscle. So when we talk about making changes to patterns or positions, we have to understand that we’re not attempting to change the pattern relative to the muscles, but we’re changing the patterns relative to the neuronal activation patterns in the brain.
When dealing with change we can’t just look at the moving part and try to restructure the pattern of movement relative to that part, we have to understand that there are a variety of elements involved in supplying information to the brain with regards to that pattern. Those elements include: the motor cortex, the somatosensory cortex, the visual cortex, and the vestibular system. So when you make a change, you have to account for all those elements, and you have to create circumstances where the athlete is wired into how each of those elements impacts what they are trying to do. I’ve talked before on this site about how the visual cortex is a major player with regards to supplying the brain with muscle management information, and more often than not, when you take the visual out of the equation, you allow the sensory cortex to get more involved in helping make the change. Plus you don’t have the eyes getting in the way by trying to push the brain to go back to the original patterns based on what it sees. So creating new patterns results in the creation of new neuronal activation patterns, and the subsequent wrapping of myelin to enhance the speed and strength of the electrical signal sent through that circuit. I mention that since to get myelin to wrap, you have to be working in a state of total focus on the subject material. To do anything less might result in miss steps back to the original patterns and result in total confusion in the brain as to what the goal is.
To answer the question as to whether different things take longer or less time. I would suspect that activation patterns that are extremely complex will be harder to break because of the inherent complexity. The time to get to a point where the new pattern or position is ingrained is still relatively similar.
Last but not least, this experiment on monkeys is probably the best experiment I’m aware of that catalogues how long it might take to fully develop a new pattern of movement. In the experiment they amputated the middle finger of the monkeys to see what would happen to all the neurons currently involved in managing that finger. Post op the area in the brain that managed the middle fingers went dark. After a period of time the management of index and ring fingers began to take over some of the neurons formerly associated with the middle finger, and after 30 days there was a loose brain map associated in that area connected to the other fingers. After three to four months the takeover of the area was complete. How this relates to change is that it takes about a month to establish the new pattern in the brain, and about 3-4 months to get that pattern to a point where you don’t even to think about it anymore, it just happens.
So the key to being successful in making changes:
Understand you’re changing the neuronal network associated with that movement
Understand that you have to consider many elements relative to that change
Know that it requires absolute focus on the task at hand to get the myelin wrapped
That it takes about a month to develop a loose network associated with the movement patterns and about 3-4 months to entrench it.