Stillness of one s hand does not. Short people are better pianists than tall people because short people are more coordinated than tall people. If large random samples of short and tall people were taken, they would most likely result in two normal distributions reflecting the fact that the majority of both populations were of average coordination with a small percentage of both populations above average and a small percentage of both populations below average. Playing legato builds technique. I played legato over a five year period with no noticeable improvement in my technical ability.
Piano technique has nothing to do with the development or strengthening of muscles.
Rather, the ability to play a piece or passage with physical ease is due to the proper coordination of opposing muscles. The ability to perform any task is based on the coordination of muscles. However, kinesiologists physicians who are experts in the science of human motion maintain that coordination is dependent upon, and is enhanced by the proper development of muscles. A woman capable of performing the task of walking bends incorrectly while lifting a heavy object and severely pulls a muscle in her back. The woman can no longer walk and must rest until the muscle can once again support the coordinated movements of that particular task.