The secret of quick and efficient movement of the left arm is to use the shoulder muscles to move the arm and forearm. The hand is never the driving force behind the action. It is relaxed, and it is brought into place by the musculature of the shoulder. The forearm is then called upon for a more accurate adjustment, while the wrist and fingers maintain their optimized positioning as described above.
The eyes determine the end point of the hand, allowing the brain to calculate the distance between the start and end positions easily.
© Jean-François Desrosby (D.Mus.) 2019
Biomechanics and performance psychology for musicians and guitarists 