What is ISR?
The Forehand Volley
John Yandell
One of the last times I saw Vic Braden was in the media lounge at Indian Wells. I forget what we were talking about but at some point he pointed at his upper arm and said something like "Johnny this joint is the key."
I think he was talking about the serve. But as I have continued to study tennis strokes over the years, I think his point applies to all the motions—even the volleys.
So in this article let's see how that works on the forehand volley.
The rotation of the upper arm in the shoulder joint goes in two directions. Clockwise rotation is ESR, or external shoulder rotation. Counterclockwise is ISR, or internal shoulder rotation.
It's been well documented in the serve, (Click Here), in the forehand (Click Here), in the two hander (Click Here) and also in the one-handed backhand. In all these cases it makes a critical contribution to racket head speed.
And you know what? It does on the volleys as well. So let's look at the forehand volley first.
Understanding these two rotations explains a disconnect in the way the volley is usually taught.
"Keep the racket in front of the body." That is maybe the most common advice coaches give on the volley.
Except that's not what happens. To a greater or lesser extent, depending on the ball, the racket head goes back beyond the plane of the body. But how and why?
To answer we have to understand the position not only of the racket head, but of the hand. On most forehand volleys, the hand stays more or less at the front edge of the body, or goes back at most to the mid torso.
The additional movement of the racket head isn't a function of hand movement, it's the function of the rotation of the entire hitting arm structure in the shoulder joint.
In the case of the forehand volley, this is ESR, or the backward, clockwise rotation of the hitting arm from the shoulder. The hitting arm and the racket rotate backward as a unit.
. This rotation can be relatively slight, only a few degrees. Or it can be much more depending on the ball.
The rotation is then forward. This is ISR. It's combined with the forward rotation of the shoulder, which is what drives the hand.
Whole Motion
So let's look at this in the context of the whole motion. The forehand volley starts with a shoulder turn, and also the movement of the opposite arm across the body.
It's basically a unit turn, similar to what happens on a forehand groundstroke. But is around half or less, something like 45 degrees.
This is then followed by the backward external rotation. The hitting arm and racket rotate backward as a unit.
The hit itself is then driven by two things. The forward rotation of the torso and the forward or internal rotation of the hitting arm.
On a routine shoulder high volley the backward and therefore the forward rotation can be relatively slight. A few degrees each way.
A good question is should players try to consciously execute this rotation? I say no. It's one of those things that the body knows how to do automatically.
Really High
But on a really high ball this rotation can be much more extreme. In this case the hand and arm will move back further as well.
Look at the extreme Sampras example. The backward rotation extends until the racket is basically parallel with the court!
So is this more extreme external backward rotation something players should model and consciously try to execute? Again I say no.
It's probably something instinctive or intuitive. If your basic technique is solid it will probably happen.
The player should focus on the turn and the forward rotation of the torso, just like on a shoulder high volley. If you try to do it purposely you will probably exaggerate the motion even more and end up not making the volley.
I could be wrong, but I think it's one of those mysterious aspects of technique that you can't think your way through. Let me know in the Forum if you agree—or not.
Next, how do these rotations apply on the backhand volley?
