What is ISR? Part 1: The Serve

What is ISR? First let me say I dislike technical terminology and especially acronyms. I think tennis can be and should be explained in simple language any coach or player can understand. But this term ISR has now worked its way into the discussion of tennis technique much the way the term pronation did over a period of years. So what is ISR? How does it work? And what value does understanding it have for players and coaches? The most common use of the term is in understanding the serve motion. But in reality ISR is present to a greater or lesser extent in all the strokes: forehands, both types of backhands, and even volleys. So let's explore all that in this new series, starting with the serve. Definition ISR stands for internal shoulder rotation. But in tennis the term shoulder rotation can be very confusing because we think of shoulder rotation as the turning of the upper body backward in the preparation and forward in the swing phase of the strokes. In tennis when we think of shoulder rotation we think of the turn first and then the forward swing. That's not what the term ISR means. Technically it...