What is ISR?
Part 3: One Handed Backhand
John Yandell
If you have studied much slow motion video of one handed backhands, one thing that may have puzzled you—as it did me--why was it almost all top players tend to open the face of the racket to at least some degree toward the end of the backswing.
When I was making the Visual Tennis instructional video many years ago, I wanted to demonstrate the simplest possible on edge swings with the racket face perpendicular to the court throughout the motion, including the take back. Yet in filming to create the models I noticed that I unconsciously was doing the same thing, rotating the racket face back slightly open before starting the forward swing.
Technically this backward rotation is called ISR—internal shoulder rotation, or the counterclockwise rotation of the upper arm in the shoulder joint. In the last two articles we've seen how this works on the serve (Click Here) and the forehand (Click Here). So now let's explore how it works on the one-hander.
Extreme?
You can see this rotation in our classic video of Ken Rosewall above, hitting what appears to be an almost flat slice drive. The backwards rotation is quite extreme.
And you can see it as well in the great modern topspin one-handers of players like Roger Federer, Dominic Thiem, Stan Wawrinka, and Stefano Tsitsipas And you can see it as well in their one-handed slice backhands.
The question is why? As we have seen in the other articles, the rotation of the arm in the shoulder joint is like a secret biomechanical element in the generation of racket speed. It's been identified by biomechanists like Brian Gordon (Click Here) and Bruce Elliot, especially on the serve. I remember one of the last times I ever saw Vic Braden at Indian Wells, he pointed at his upper arm and said something like “Johnny this is the rotation we need to understand."
But, particularly on the one-hander, this understanding has never been recognized much less passed into common teaching terminology. This is one thing that has continued to amaze and excite me in working on Tennisplayer for almost 20 years, it seems there is always something new or additional to explore and understand.
Two Rotations
ISR is one half of a pair of rotations. The other is ESR—external or clockwise rotation of the upper arm in the shoulder joint. In the last two articles we have seen how these rotations work together.
On the serve, ESR sets up the massive ISR rotation of the arm and racket. This is when the racket edge ends up on edge perpendicular to the court in the extension of the motion.
On the forehand we see a more complex pattern. Typically, there is internal rotation at the start of the motion. Followed by external rotation moving into the backswing. Then massive internal rotation in the forward swing ending in the windshield wiper finish.
On the one handed backhand, the pattern is different. We see ISR or internal shoulder rotation in the backswing, opening the face. This sets up ESR or external rotation in the forward swing.
Depending on exactly how open the face is, this external rotation in the forward swing is to a matter of degree. On the topspin drives this seems to be 45 degrees or more.
It varies with the player as in so many elements. But it's gotta be a power source. Or you wouldn't see it so universally.
It's there to a lesser or greater to degree in all pro one-handers. The racket face then goes from some degree of open to square at the contact and into the follow through.
This forward rotation is critical. At the extension the racket face rotates until it is perpendicular to the court. But again this movement is not an element that is discussed in teaching.
In slice backhands, the rotation is usually less, at least compared to Rosewall. Less rotation is especially common in the more extreme modern slice forehand when the forward swing is far more downward with the tip of the motion with the racket ends up pointing downward at the court.
But it is still elemental in the swing. So what does this mean for us?
Not in my opinion something that should be modeled. I had a student years ago who had an extreme version of the open face backswing and he took it way behind his body. He absolutely could not hit his backhand crosscourt.
It made him so late at contact that at best he could hit a slice down the line. He used to like to play sets and it was sad. He'd hit slice backhands down the line or to the center. Off those I could hit forehand crosscourts that he couldn't cover.
Understanding?
It's great to understand the biomechanics. But understanding biomechanics are not necessarily the answer to having a great one-hander.
Regardless of the backswing, the rotation finishes with the racket on edge. This is the key in all one handed backhand drives. 90 degrees of rotation in the forehand swing will give you a very good one-hander.
Understanding is great. Hope this article clarifies a lot. But then there is how to hit the shot.
I say model the simple model of a backswing that stays on the players' side with the racket vertical face. And yes you will probably develop naturally some additional rotation in the backswing. If you can't resist experimenting with this on purpose be careful!
