Measuring Change:
Radar Technology in Teaching
By John Yandell
Do alleged technical "improvements" in your strokes actually make a difference in the effectiveness of your shots? Most players have wondered that, and every teaching pro who is honest with himself has as well--myself included.
Now there is a way to answer that question quantitatively. An example: my student Ken So, increased his ball speed on his forehand by 15% in an hour. That's a huge gain at any level.
How do I know this is true? Because I measured it with a new generation radar gun called the Pocket Radar, (Click Here). This is a very cool piece of technology: compact, easy to use, and inexpensive at about $300.
How valuable is it? It changes the way the game should be taught, as valuable and essential as high speed video. It's the missing piece that validates the entire teaching process.
It works like this. Point the Pocket Radar at the line of the shot as the ball comes off the racket, push one button, and the speed of the ball comes up on the digital display.
It's very accurate according to company tests versus the pro systems, is battery powered, and yep, it fits in your pocket. (Or around your neck with the strap that comes with it.)
Obviously, the technology isn't just for working on the forehand. You can apply it to any stroke.
And yes, some people are obsessed with how fast they can serve. That's why they want a radar gun to prove that to themselves or others. However, if you are like a few players I've tested, your claim that you can hit that serve 120mph might face an unpleasant reality check.
But back to the case at hand. How did we use it in creating the dramatic improvement in the forehand of my friend, chiropractor, and student Dr. Ken So? Ken took up tennis as an adult and has continued to play and improve continuously over the years.
He and I worked together in the 1990s and you can see the influence in his forehand of the forehand model from my book, Visual Tennis. (Click Here for a link to the book that first presented the system.) That model is based on an eastern grip, begins with a unit turn, has a relatively compact backswing, and has a smooth long finish.
When Ken and I reconnected recently I thought his swing still looked way better than the huge majority of players at the San Francisco Tennis Club where we both belong, including a lot of players with much higher NRTP ratings than Ken.
But could his forehand be significantly better? More of a weapon? Definitely. And the radar gun provided the evidence.
Here is the process we followed. Without telling Ken what I was doing I had him warm up and then hit forehands while I measured the ball speed off his racket. At the same time, I filmed his forehand using my Casio high speed camera.
For the measurements to be viable the incoming speed of the ball also needed to be consistent. I measured that as well as the ball came out of my Sports Attack ball machine.
I looked for forehands where Ken both found the center of the racket and the ball landed in the court. I recorded 10 of those. The ball speed off his racket ranged from 46mph to 58mph.His average forehand ball speed was 53mph.
Then we went inside my office just off the court and took a look at his technique. Since I first worked with Ken, I have spent more than 15 years studying pro tennis in high speed video. The result has been greater knowledge and corresponding advances in my teaching models for all the strokes.
On the forehand the first important change in my approach over time has been increased emphasis on the body turn and especially the stretch of the left arm across the body--something I've written about many times on Tennisplayer. (Click Here for one example.)
Following the Visual Tennis model, Ken had a good turn--again way better than most of his fellow club members. But I felt pushing the turn further to the pro checkpoints from my revised model would make a big difference.
All the top players have some version of this turn with the left arm stretch. But no one demonstrates it more purely than Roger Federer.
The turn is initiated with the body--the torso and the feet. The racket stays in front of the body but starts to move back as the body turns.
The shoulders then continue to rotate until they have turned more than 90 degrees to the net--more like up to 120 degrees.
The left arm stretches fully across so that it is perpendicular to the sideline and parallel to the baseline. The head is facing the ball with the chin turned over the left shoulder. This position is critical in pro tennis, but translates to players at virtually any level. It is a pro technical element that virtually any player from the 2.5 level up can easily adopt. So we looked at the high speed of Roger's turn side by side with Ken's. We saw the differences.
Then we went out on the court and Ken worked on physically modeling the left arm stretch and the checkpoints, as well as visualizing what the turn looked like in his mind's eye. I let him hit a few balls to get the feel of the new position, then I got out the radar gun again.
I looked for the same two characteristics. Solid contact and a ball that landed in the court. On the first 10 ball trial we saw an immediate increase in ball speed.
The range of his forehand speeds was 57mph to 60mph. The average was 58mph. That was almost 10 percent more ball speed, virtually instantaneously. And less speed variation from ball to ball.
Then I had Ken go back to working on the model and the feeling of the stretch without the ball and on the imagery. Then we did a third trial.
The ball speed increased again. The range was 58mph to 62mph. The average was 60mph. 7 of the 10 forehands were 60mph or higher.
So in an hour his forehand went from an average of 53mph to an average of 60mph. That's an increase of almost 15%. And corresponding, 15% less time for the opponent--a huge factor, especially for club players.
Ken was happy. And so was I. I knew that I had seen this type of speed increase with hundreds of players at all levels over the years. But the radar gun took that belief to a new level of certainty.
The other phenomenal benefit of having actual speed data lies in explaining the feeling that goes with a world class technical forehand. Many times players report that the forehand feels "easier" when they execute the left arm stretch.
Sometimes though they wonder if that feeling of ease is a good thing. Maybe they aren't trying hard enough? And with that doubt comes the tendency to muscle the ball rather than let the power unwind naturally from improved technique.
The fact is that a rocket forehand hit with world class technique does feel effortless. That's one of the greatest things about tennis--that feeling.
I'm sure I will be writing more about my experiences with pocket radar. Stay tuned for that. It's a critical step in the evolution of coaching.
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