The Sampras Serve: The Heaviest and the Greatest?
By John Yandell
Sampras' motion frame by frame.
If you watched any of the recent exhibitions between all-time greats Roger Federer and Pete Sampras you were probably amazed at the effectiveness of Sampras’ serve. The fast courts were to Sampras’ advantage, but it was obvious that even at age 36 his delivery is still amazing.
Federer has made a habit of neutralizing Andy Roddick’s 140-mph serve with his phenomenal returns. But against Sampras, Federer struggled to put the ball in play and many of his returns appeared uncharacteristically weak. Sampras’ ball somehow just looked different—it appeared much “heavier” than the top servers in the current pro game. Was that an illusion? Or is there really something unique in his motion that makes his serve different?
I think the answer is yes. To explore how Sampras hits a heavy ball, let’s start with some research into the relationship between speed and spin in his motion. Then we’ll look more at the motion itself, using high-speed video footage filmed at another exhibition match, this one versus Sam Querrey at the Tiburon Peninsula Club in Marin County, Calif. We’ll see several distinctive elements that explain the quality of Sampras’ ball and his success against Federer. These unique components in his motion make Sampras’ serve one of the greatest, if not the greatest, of all time.
Heavy Ball
Speed and Spin
Research based on quantitative filming in actual match play reveals that Sampras achieves phenomenal spin rates. This is what sets his serve apart. It’s probably best understood as a high-velocity kick.
Throughout his career, the speed on his first serve typically ranged between 115 mph and 130 mph—fast, but not the fastest even in his own day. What distinguished his delivery was the total amount of spin, and especially the type of spin, compared to other pros. Research shows that Sampras was averaging over 2500 rpm of total spin on his first serve. That’s a phenomenal amount of rotation. It’s 50 percent more spin than many other servers with similar velocities. Just rev up the tachometer on your car to 2500 rpm if you want to feel how much force this involves.
The research also shows that as important, or more important than the total amount of spin is the type of spin. Of particular importance is the topspin component. First, it’s important to realize that a pure topspin serve is a myth. The research conclusively demonstrates that the majority of the spin on all serves is sidespin.
Yet we found that on average, Sampras’ topspin component was 35 percent, much higher than other servers we measured. To use the familiar analogy of a clock face, his ball was spinning from 8 o’clock to 2 o’clock. This diagonal was steeper than any other player we studied. So the factors that make Sampras’ serve appear different are more total spin, and especially, more topspin. The higher topspin component means that the ball is significantly higher and heavier at the time of the return. The data showed that Sampras’ serve bounced six inches higher than a serve hit at the same speed with a smaller topspin component. The ball height at the moment of the return could be above five feet. That puts the ball at about shoulder height for a player who is six feet tall.
Sampras’ serve also was literally heavier because it was spinning up to 20 percent faster after the bounce. The physics of the ball bounce on the court surface are complex. But, suffice it to say, a ball coming into the bounce with more topspin will interact with the court differently, conserve more of the energy in the serve, and leave the court with additional spin compared to a ball at a similar speed but with more sidespin.
This is the secret of the so-called “heavy” serve and why Sampras’ ball just looks different. The total amount of spin and the relatively high amount of topspin make the return much tougher because the ball is bouncing higher and spinning significantly faster at contact. A former tour player once compared trying to return Sampras’ serve to trying to return a bowling ball. To him it seemed physically impossible with a tennis racquet.
The Motion
How does Sampras produce this unique ball? For starters, look at the depth of his racquet drop. The racquet falls along his right side and the face of the racquet is on a plane that is perpendicular to his torso. Notice how his upper arm is almost in line with his shoulder. This shows his tremendous shoulder flexibility.
Now watch the action of the hitting arm frame by frame going up to the ball. The elbow extends. Then five or six frames before the contact, watch the hand and racquet start to turn into the shot. As this rotation progresses the wrist moves from a laid back to the neutral position at contact.
Now the hand and arm rotation continues into the follow-through, rotating primarily as a unit from the shoulder joint. The extent of Sampras’ arm rotation, typically referred to as “pronation,” is incredible, easily 90 degrees after contact.
Ball Position
The key to the topspin is the placement of Sampras’ toss. Compared to most other top servers, his toss is further to his left and closer to the edge of his head at contact. His motion to the ball, then, is more radically upward with his hand and racquet. This explains the “high” elbow position in his motion as well. The arm releases and bends sooner than in a motion that is moving more from left to right.
Knee Bend and Torso Rotation
Two other important factors contribute to the total energy that gets transferred into this 125 mph super-heavy kick delivery: Sampras’ incredible body rotation and the explosive uncoiling of his legs.
Coil and Knee Bend
Sampras starts his motion with his shoulders basically square to the baseline, but during his windup he turns off the ball as far as any player in the game since John McEnroe. This body turn is key to understanding his massive combination of velocity and spin. Because he turns so far, Sampras naturally gets tremendous leverage when he rotates back into the ball. The amount of body turn is directly related to his stance. If you draw an imaginary line across his toes, and another imaginary line across the front of his chest, they are essentially parallel at the completion of the turn. Put another way, the angle of his stance corresponds to the angle of his body at the completion of his turn.
Sampras’ turn also aids disguise. Federer commented after one of the exhibition matches that he could not read Sampras’ serve. Like McEnroe before him, the radical forward body rotation into contact probably disguises the path of the racquet, a critical factor given the micro-fine timing required to hit the modern pro return. His disguise is probably also related to that ball position at contact. Incredibly, Sampras is able to hit to anywhere in the service box with the left-positioned toss.
Legs
The footage shows that Sampras still has that same tremendous knee bend—the second factor in adding energy to his delivery. But it’s important to understand that the coiling of the legs really only begins after he has released the toss.
Note that as the toss arm is going up, he is standing almost straight up with just a little flex in the knees and his weight appears equally distributed on his feet. As the tossing arm continues to extend, he begins to drop his weight, bending his knees and then shifting the majority of the weight onto the left front foot.
The completion of the knee bend coincidences with the completion of the turn, and with the full extension of the tossing arm. The legs, hips and shoulders all uncoil as he launches upward into the ball and outward over the court. The ball is tossed in front, but note that the actual position of the racquet when it strikes the ball is just at the front edge of the body—roughly even with the front of his face.
The explosive full body motion, full racquet drop, incredibly flexible shoulder, and ball position are the factors that account for the incredible weight of shot, or “heaviness,” that surprised Federer. The fact is that Sampras still serves as well or better than any player in the current game—and probably in the history of tennis.
