Ball Spin in Pro Tennis

John Yandell

The two primary characteristics of the shots hit in professional tennis are that they are hit with great velocity and heavy spin. Because of the radar guns on the serve, at least something was known quantitatively about the velocity of the ball.

The study of ball speed conducted by Advanced Tennis researchers showed that the radar guns told only the first part of the story about ball speed in pro tennis. We found that the ball slows down dramatically on the serve from the initial velocity recorded by the radar gun, both before and after the bounce, and did the same on the other shots as well.

Questions Regarding Spin

A first serve might be traveling 120mph when it left the racket, but how fast was that serve spinning? How much more spin was there on a "spin" second serve compared to a first serve? What about the heavy topspin forehands of the European players? How did this compare with players with a more classic style? How "flat" was a flat ball? How "heavy" was heavy or exaggerated spin? Did balls hit with underspin spin more or less than topspin? What about volleys and dropshots?

In 1997, we got the chance to answer some of these questions. Working with a team of other researchers from Cislunar Aerospace, and USTA Sports Science, we had th e unique opportunity to film U.S. Open on Arthur Ashe Stadium court.

During 4 days of filming, we were lucky to capture enough footage to measure the spin rates on almost twenty of the top players in the world, both men and women. From the raw data, we were able to analyze the spin on over 700 individual shots, including 1st and 2nd serves, groundstrokes hit with both topspin and underspin, return of serves, volleys, overheads and drop shots.