Pronation is one of the most important, yet least understood motions in the tennis serve. Serve pronation is critically important technique that allows you to accelerate your racket head through the tennis ball, adding spin and power. Every high-level tennis player – whether in college or on the pro tour – uses pronation when he serves.
So what exactly is tennis pronation? If you take your hands and place them out in front of yourself with the palms facing each other, and then rotate at the forearm and the wrist together downwards, that is pronation. If you rotate your arm and wrist the opposite direction so that the palms of your hand face upwards, that is supination. So rotating down is pronation, and rotating up is supination.
A different way to think about tennis pronation is using the karate chop analogy. If I karate chop towards the camera and then pronate, my palm will face the camera.
My favorite way to think about tennis pronation is to use the cellphone analogy. If I’m talking on the phone, and I want to show you who I am talking to, I have to pronate my wrist to show you the screen. If I want to look at the screen, I have to supinate my forearm and wrist back.
Let’s now look at me shadowing pronation on the tennis serve. What you see in the video is that I start my upward swing towards the tennis ball by swinging up on edge with the racket (like a karate chop), almost like I am trying to frame the ball. I then pronate with the forearm and the wrist to get my strings facing the tennis ball at contact on my serve. If we continue playing the video forward, you can see that I keep pronating through contact into my follow through.
Let’s now take a look at tennis serve pronation from the back view at 2:20 in the video above. Again, you can see that I swing up on edge at the tennis ball, but then I pronate to open the strings up to the ball before contact. It almost looks like I’m high-fiving the tennis ball with my arm, wrist and racket. If we watch it again, you can see that I continue pronating on my serve through contact and into my follow through.
How exactly does pronation add power and spin to your tennis serve? When I swing up on edge at the tennis ball and then pronate, I rotate the racket 90 degrees in a very short period of time. If I allowed that rotation to continue at that speed, you can see that the tennis racket spins on its axis quite quickly. That spin has a rotational energy associated with it, and with a serve at a high level, it’s quite a bit of energy. When I pronate and make contact with the ball, that rotational energy is transferred into the tennis ball, and that’s what adds power and spin to the tennis ball.
Now, I want to be clear, because the act of pronating itself doesn’t add spin to the tennis ball. Spin is added to the ball by brushing across the tennis ball, and we have already established that pronation makes the tennis racket move faster. If you can move the racket faster across the tennis ball faster, you will apply more spin to the ball, and more spin means more control.
Let’s now look at some high speed video of former ITF World #1 Junior Frank Salazar and see how he prontates just before he makes contact on his tennis serve. Let’s start him out in the racket drop position, and as he starts to swing up you can see that his tennis racket is on edge to the tennis ball. From this spot, he’s going to pronate to make contact with the tennis ball. Let’s rewind and watch how as he pronates, the tennis racket really starts to accelerate more than it had previously. After contact, Frank continues pronating into his follow through. Again, by adding pronation to your tennis serve motion, you will add that power and spin that is so important to the modern game.