The Three Service
Rhythms

By Doug Eng, EdD PhD

The service motion is arguably the tennis stroke with the greatest variety, and perhaps also the most analyzed. Debates on the ideal toss, how power is generated, and the use of the wrist have been hotly contested, and tennis coaches and players will probably never reach agreement on these issues.

In this new series of articles, however, I want to investigate a less well-known and less discussed aspect of the serve that is just as important or more important in developing a great serve. This is the rhythm of the motion.

I believe there are three distinct rhythm styles.

These are:

To comprehend what goes on in high level serving you have to understand rhythm styles and what they mean. And the same goes for building or improving your own service motion.

The Three Rhythms (left to right): Andy Roddick in the abbreviated rhythm, Andy Murray in the classic rhythm and finally Dinara Safina in the staggered rhythm.

Classic, Abbreviated, Staggered

In the classic service rhythm, the hands move down together and then up together. Andy Murray and Roger Federer are two great examples. At the toss, their racket arms tend to point backwards and away from the body, at a height somewhere in the mid torso range.

But if we look at the pro game we also see there are two other successful options. Andy Roddick, one the game's all time great servers, uses an abbreviated rhythm. With his shortened backswing, this means that he keeps his racquet hand much higher at the toss. Gael Monfils and Rafael Nadal are also abbreviated rhythm players.

Still other players use what I call a staggered rhythm, tossing the ball when the racquet hand is much lower, down near the hips. Jo Wilfred Tsonga, Tomas Berdych, Robin Soderling, Dinara Safina and Venus Williams are all examples of staggered rhythm servers.

So what are the real differences in the 3 styles? In this first article, I will present some quantitative measurements involving the release of the toss, the toss height, and the timing of the motion.

I believe that these differences in rhythm style inevitably lead to other important technical differences in the motion. This is because rhythm and technique are intertwined in a cascade-like chain reaction. What happens at point A will affect B and eventually point C.

These differences, though not usually noticed, have important consequences for the development of the serve at any level. This is also why trying to patch a stroke by focusing just on one part or aspect of the motion is often ineffective.

Those are issues I will look at more closely in part 2. In a third article, I'll share my thoughts about the three options and how to put all various components together for yourself depending on your own rhythm style.

The Data

At the start of my study, I looked at the motions of nearly 100 ATP and WTA touring pros in high-speed digital video. From there, I did an in-depth study of 36 pros (23 ATP and 13 WTA) by studying 75 individual video clips. The selections were based partially on popular interest in particular players, but also on the quality of the videos (e.g., those that gave unobstructed views and the best angles).

My research shows, first, that understanding the toss height is critical in understanding the differences in the three serving rhythms. Toss height has been the subject of considerable debate, with many opposing theories. One argument is that the ideal toss height should be just at the height of the contact point. At the other extreme, you hear that the toss height should be two feet above the contact point, or even more.

The low toss argument is that the ball reaches zero velocity at the top of the toss, and is supposedly easiest to hit. The high toss argument is that more time is required in modern serving with the use of increased torso rotation and deeper knee bends. Researchers such as Howard Brody have also argued that the velocity of a dropping ball from a higher toss naturally contributes to topspin.

My own analysis of the serves of top players shows that the toss height can not be developed based on some arbitrary principle. There is no one correct answer. Rather, I believe, toss height is a function of the server's natural rhythm. My study shows there are direct correlations between rhythm style, the point of release of the toss, the height of the toss, and the timing between the toss and the contact.

Release Points

Let's start our exploration of these issues by measuring the relationship between toss release points and rhythm style. The release point is defined as the moment when the ball completely loses contact with the tossing hand.

Although not commonly understood, the point at which players release the ball can vary substantially. Video analysis shows that touring pros release the ball anywhere from about eye level to 10 inches above the head.

There are excellent servers at both ends of that range. James Blake had the lowest release I studied at about eye height. Fernando Gonzalez and Marat Safin released as high as 9" or 10" above the head. But I found these were the exception and almost all releases were head high to 4" above the head.

When I looked closely at these release points, I found there was a direct correlation between rhythm style and the height of the release. To determine this, I measured the position of the racquet and racquet hand and arm at the moment the ball cleared the player's hand.

The differences were small, but statistically significant. Abbreviated rhythm players had the lowest release, on average a half an inch above the head. Staggered rhythm players had the highest release, at 2.5 inches. The classic rhythm players were in between, 2 inches above head level.

Tossing Height

The second variable I studied was tossing height, and the timing between the moment of release and the contact. Again I found a direct correlation with rhythm style. For both men and the women, the abbreviated rhythm used the lowest toss, followed by the classic, and then the staggered.

For abbreviated players, the toss was 20.5 inches above the contact point. For the classic players the toss was about 23 inches above contact point. For the staggered rhythm the height was about 29 inches.

Timing

A third variable to look at was the timing between the moment of the release and the contact. How did the actual time interval relate to tossing height?

If you time from the release point to the contact point, you find that in pro tennis there is a substantial range of intervals. In my analysis, I found the timing varied from about 0.6 to 1.24 seconds. This means some players are using more than twice as much time between the release of the toss and the hit.

A possible complication in correlating timing and tossing height is the difference in the height of the release points. Another is that players, including tour-level players, have different backswing speeds and even hitches in the backswing.

For example, the most likely service rhythm to have a hitch or pause is the abbreviated motion. The least likely is the staggered motion because the racquet arm starts upward relatively late and must keep moving in order to catch up to the tossing arm.

Yet, despite theses differences in the exact release point and in backswing speed, there is still a very strong correlation between the height of the toss and the timing from release to contact point. By the way, no player in this study hit the ball at the apex of the toss, despite what some coaches may claim.

The table shows the average time from release to contact as correlated with the height of the toss. For the men the shortest time from release to contact was for the abbreviated, followed by the classic, and then the staggered.

For the women, the abbreviated also had the shortest interval. However the interval for the classic rhythm actually turned out to be longer than for the staggered.

Interestingly, the lowest toss and fastest rhythms were for Rafael Nadal and Donald Young. They both tossed with an apex as little as 6-8" inches above the contact point, with a duration of 0.6 to 0.7 seconds between release and hit. What makes this unusual is that Nadal's rhythm is abbreviated while Young uses a classic rhythm with the racquet arm almost parallel to the ground at the release point.

Racket Hand Height

Now, after looking at my data on the toss, let's go back and review the position of the racket hand at the moment of release, and correlate this with the variables we've analyzed. Now we can see a more complete picture of the differences in the rhythm styles.

For the abbreviated rhythm, the hand and racquet are usually in a position at or above the shoulders, similar to Rafael Nadal or Andy Roddick. With the classic rhythm, the arm is stretched away from the body, pointing backward, similar to Andy Murray or Roger Federer. With the abbreviated rhythm, the hand and racket are quite low, below the waist with the racquet head pointing somewhat down, similar to Tsonga or Berdych or Safina.

With the abbreviated rhythm, the racquet tends to travel the least distance, the toss is relatively low and the rhythm fastest. With the staggered rhythm, the player has barely begun the backswing and the racquet must travel the farthest. Therefore the ball toss must be generally the highest and the rhythm the slowest.

But the classic and staggered motions were similar in timing and toss height compared to the abbreviated. Some classic servers tend to slow down or momentarily pause the racquet when the tip is pointing upward, which may increase the overall time. The staggered motion keeps moving so the racquet ar can catch up. Therefore timing on the classic motion tends only to be slightly faster on average than the staggered motion.

The abbreviated rhythm is least likely to tilt the shoulders initially since the racquet arm often goes almost straight up. Therefore the shoulders tend to be almost parallel to the ground and the release tends to be closer to the top of the head.

The staggered rhythm initially creates the greatest shoulder tilt as the racquet arm remains down below the waist. Hence, the release point tends to be higher due to the greatest initial shoulder tilt. Because the shoulders are tilted at release, the wrist tends to extend slightly in order to give an accurate vertical toss. If there were no wrist extension, the ball toss would be backwards.

This staggered rhythm has been most criticized as difficult due to the length of the arm swing after the toss and the height of the toss required. However, in this first article, I want to simply observe and classify rather than critique mechanics and techniques.

The abbreviated rhythm has gained plenty of interest in the last few years, especially with the emergence of Andy Roddick. In addition, Rafael Nadal, Gael Monfils, and Justine Henin also use this rhythm. But the abbreviated motion isn't new. In the 1980s, Ed Krass, a noted coach in Florida and former college coach endorsed this motion. When the ball is released on the toss, the racquet arm is generally at or above the shoulders already.

Although I classify these individual rhythms together, often the racquet may be in different positions such as straight over the head or just above shoulder height (e.g., Roddick) at release.

One important factor to consider is gender difference. On all three rhythms, WTA players served at slower times as shown in the above table. Naturally, their tosses are also higher.

I offer a simple explanation: as with speed velocities, men generally serve harder and achieve greater racquet head speed. Most WTA players cannot generate the same racquet head speed on the backswing as ATP players. This is important to note since many criticize female pros for not generating higher speeds and spin.

Rhythm and Other Elements

So serving rhythm is defined by the relationship between the position of the arms at the toss, the tossing height and the timing of the motion.

Keep in mind these relationships are general correlations and there are exceptions. Tennis players are humans with individual differences. However rhythm style is critical because I believe it influences other key movements in the motion.

My research shows me that players have certain co-ordinations and/or swing speeds in different parts of their motions that lead them to develop particular rhythm styles over time. Or it can be the other way around.

The point is that rhythm styles effect how players use the kinetic chain, in which forces move upwards through the body starting from the ground. Especially in the serve, the chain can be complex because several body parts may be undergoing simultaneously actions involving different types of movement such as rotation around different axes, flexion, and extension. The difficulty lies in the number of variables and dimensions.

Basically, however, I want to make the case that since the movements of multiple body parts occur simultaneously, different initial movements lead to slightly different subsequent movements and results.

Specifically I believe the arm positions and rhythm style can affect both the initial footwork and the subsequent upward or forward leg thrust towards the ball. This means there is a relationship between the rhythm of the arms and:

These are some of the issues we will delve into in Part 2. Stay tuned!

Note: special thanks to USTA Player Development and Bobby Bernstein for use of video clips at the 2008 US Open.