Ball Speed in Pro Tennis
Pro ball-speed study from high-speed video: how fast do pros actually hit, and what happens between racquet and opponent.
Ball Speed in Pro Tennis
By John Yandell
What happens to the speed of the ball over the flight of the serve?
It's indisputable that pro tennis has become a supersonic sport. But what do we REALLY know about the incredible speeds of the shots hit by the best players in pro tennis?
We know from the radar guns that pro serves routinely reach serve speeds of 120 to 130mph, and that players such as Andy Roddick and Taylor Dent are capable of hitting serves that reach speeds of 150mph--and more.
But what part of the serve does the radar gun reading represent? What happens to the speed of the serve over the course of its flight to the receiver? Is it going still 120mph at the time of the return?
What about the speed of the other shots besides the serve? How fast are players hitting forehands, backhands, volleys, overheads and returns? A common perception is that a great return can come back faster than the serve. How does this perception square with reality? The answers we found to all these questions may surprise you.
It happens too fast for the human eye to see. For this reason, it has gone completely unnoticed by experienced students of the pro game. But the results of our analysis showed that the ball actually slows down dramatically as it travels between the players. Virtually every shot in pro tennis loses at least 50% of its speed by the time it reaches the opponent. That's right, half--and usually even more. This was true on the serve. It was also true on the groundies, the returns, volleys, and overheads.
Let's look at how we did our study and the results on all the strokes. I think you'll find it as fascinating as we did. At the end, we'll also see some important implications for coaching and playing that can have a huge effect on your ability to time the ball, particularly on your opponent's biggest shots.
What about the speed of all the other shots besides the serve?
The Project
In 1997 and 1998 Advanced Tennis researchers, working in collaboration with Cislunar Aerospace in an educational program funded by NASA, set out to do the first ever study of ball speed in pro tennis. To do this, we filmed several matches played by the great Pete Sampras. We used two cameras set at right angles high above the court, one shooting across the net, and the other across the baseline.
Advanced Tennis principal scientist Nasif Iskander then digitized dozens of Pete's shots, capturing the trajectory of the ball in its flight between the players' rackets. Using an original piece of motion analysis software he created, Nasif was then able to measure the speed of the ball and how it changed over the course of the flight of each shot. (AdvancedTennis.com)
All told, Nasif analyzed over 50 Sampras hits by plotting over 4000 separate points in the flight of his and his opponent's shots. For the first time we had data on the speeds of the shot patterns of a world class player. This included the initial speed of the ball on every stroke and what happened to this initial speed both before and after the bounce, and at the time the opponent hit the next ball.
To understand the speed of the ball over the flight of the shot, we filmed the trajectory with two wide cameras.
Results
Nasif found that the maximum speed recorded by the radar guns on the serve corresponded pretty closely with our digitized shot analysis. The average speed for the Sampras first serves in our digital analysis was 120mph. The average radar gun speed for the same serves was 117mph, a difference of less than 5%.
What spectators see on the radar guns is probably fairly accurate (although possibly less accurate on wide serves which travel at more of an angle to the radar gun beam.) But that's just the initial speed. What about the rest of the flight of the serve? What happened to it in the 3/4s of a second or less it took for Pete's serve to reach his opponent's racket?
The answer is that over the course of its flight, that 120mph serve actually slowed down to under 60 mph. It was going less than half its initial speed at the time of the return. This dramatic deceleration occurred in only a fraction of a second--3/4s of a second or less. So why and how does this happen?
There are two factors. The first is air resistance prior to the bounce. By the time the ball had bounced on the court, every Sampras shot--serve, groundstrokes, volleys--had lost roughly 25% of its initial speed due to the effect of the air on the ball, technically, the "drag".
The second factor is the friction of the bounce on the court. At the bounce, the ball lost another 25% of the initial speed, or slightly more, due to the friction between the bottom of the ball and the court surface. This is a radical change in speed that occurs in only 4 milliseconds or 1/250th of a second.
In total, Nasif analyzed 29 first serves. The analysis program showed that the average maximum speed of these serves was 120mph. Before the serve bounced in the service box, this average speed of these serves was down to 87mph due to the air resistance or drag on the ball as it traveled toward the receiver. After the bounce, the average speed serve was down to 62 mph. In the 4 milliseconds that the ball was in contact with the court, it lost 25mph.
Number of Serves
MPH
Pre-Bounce
Post Bounce
End
29
120 MPH
87 MPH
62 MPH
54 MPH
Then, as the ball traveled toward the opponent after the bounce, it continued to lose even more speed. At the point the player hit the return--or the ball passed the baseline in the case of an ace--Pete's serve lost on average another 8mph. So that first serve may start off at 120mph, but it reaches the receiver at about 54mph. The following chart breaks it down so you can see the serves in both courts, both wide and down the middle.
Sampras 1st Serve:
Number of Serves
Location
Max MPH After Hit
Pre-Bounce MPH
Post Bounce MPH
End MPH
4
Deuce DTheM
127 MPH
89 MPH
67 MPH
58 MPH
7
Deuce Wide
113 MPH
81 MPH
57 MPH
50 MPH
13
Ad DTheM
123 MPH
90 MPH
63 MPH
55 MPH
5
Ad Wide
117 MPH
86 MPH
60 MPH
53 MPH
The Return of Serve
If the first serve in pro tennis is losing half its speed prior to the return, what about the speed of the return itself? Is it possible that the perception that the return can be "faster" than the serve actually true?
Nasif was able to measure the speed of 10 returns hit by Pete's opponents, as well as 3 returns hit by Sampras.
So is the return ever "faster" than the serve? Let's clarify the question. Is the initial velocity of the return faster than the initial velocity of the serve? Definitely no.
Is it possible that a great return comes back faster than the serve?
The initial velocity of the return is nowhere close to the initial velocity of the serve. The fastest return measured was a backhand hit by Sampras opponent Jonathan Stark that reached 70mph. The fastest return measured for Sampras was a forehand at 65mph. So the returns we recorded had an initial velocity equal to at most 60% of the initial velocity of a first serve. But put the question another way. Is the speed of the return faster than the speed of the serve just before it is hit? That answer is yes.
As outlined above, the analysis showed that by the time of the return, a 120mph first serve has slowed down by more than half, traveling at roughly 55mph. Our analysis also revealed that the initial velocity of many returns was higher than than that. On Pete Sampras's fastest return, for example, the speed of the serve had slowed 60mph at the time of the return. Sampras's return had an initial velocity of 65mph, about 10% higher than the speed of the ball at the time of the hit .
The fastest return we recorded, a backhand hit by Jonathan Stark, left Stark's racket at 70mph. This return was on a Sampras serve with an initial velocity of 125mph. that 125mph serve had slowed to 54mph just before Stark's hit. Stark's return added 16mph to the ball speed, increasingl the speed of the ball by about 30%. For the 3 Sampras returns studied, Sampras averaged 56mph, an increase of about 4mph over the speed of the incoming ball.
Pete's returns averaged 56 mph off the racket--about 4 mph faster than the speed of the ball prior to contact.
It should also be noted, however, that the average initial velocity of the return could also be less than the speed of the oncoming ball. For example, one Sampras backhand return left his racket at 49mph, 6mph slower than the incoming ball which was 55mph.
Based on the limited number of returns analyzed, it is difficult to conclude what the maximum potential speed of the return might be. Most all of Sampras's returns showed a slight increase in speed. One return by an opponent showed a 30% increase in speed. We can speculate that the most aggressive returners in the game could hit returns with even more velocity, approximating or exceeding the velocities of the groundstrokes as analyzed below.
Returns Over the Course of the Flight
After leaving the racket, the returns showed substantially loses in this initial velocity over the course of the flight. In fact the percentage of speed lost was slightly more on the returns than it was on the serves. Sampras' returns averaged an initial speed of 56mph, but slowed to an average of only 20mph at the end of their flight.
These 3 returns were typical of the returns of Pete's various opponents, which also lost well over a third of their speed before the bounce. The bounce of the ball on the court caused the shot to lose over a third of the remaining speed. After the bounce, the return continued to slow down, losing another 15-20%.
Sampras' Forehand Return:
Forehand Returns
Pre-Hit Speed
Max MPH After Hit
Pre Bounce MPH
Post Bounce MPH
End MPH
1
60 MPH
65 MPH
40 MPH
30 MPH
24 MPH
Sampras' Backhand Return:
Number of Backhand Returns
Pre-Hit Speed
Max MPH After Hit
Pre Bounce MPH
Post Bounce MPH
End MPH
2
48 MPH
51 MPH
32 MPH
21 MPH
18 MPH
The Groundstrokes
This was in fact almost exactly the same speed the ball was traveling before the hit on Sampras's groundstrokes, an average of 19mph.
Our data showed that 9 Pete Sampras forehands had an average initial velocity of 76mph, with the fastest being 82mph. On the backhand, we measured 2 Sampras hits that averaged 69mph.
This equaled an average increase of over 50mph in the speed of the ball compared to its speed just before the hit, which averaged about 20mph.
The pattern of deceleration on the groundstrokes closely matched that of the serve and return. On average Sampras's groundstrokes started at about 70-75mph and finished at about 30mph.
Sampras Forehand:
Number of Forehands
Pre-Hit Speed
Max MPH After Hit
Pre Bounce MPH
Post Bounce MPH
End MPH
9
19 MPH
76 MPH
49 MPH
34 MPH
31 MPH
Sampras Backhand:
Number of Forehands
Pre-Hit Speed
Max MPH After Hit
Pre Bounce MPH
Post Bounce MPH
End MPH
2
17 MPH
69 MPH
49 MPH
32 MPH
28 MPH
Pete's backhand volley averaged a little over 40mph off the racket.
The Net Game
Our study was able to analyze the speed on 10 Sampras volleys as well as 4 overheads. Five forehand volleys had an average initial speed of 47mph, with the highest hit at 60mph. On the backhand side, 5 volleys averaged 44mph with a high of 54mph. In general, then the volleys had about 60% of the initial pace on his groundstrokes.
His volleys left his racket consistently faster than the speed of the incoming ball. The average incoming ball was traveling about 40 mph at the time of the hit, for an increase of around 5mph.
The deceleration pattern on the volleys followed that of the other strokes. On average the volleys lost about half their initial speed after the bounce, and almost 60% of their speed by the end of their flight. This means that a volley that started out at around 45mph slowed down to about 20mph at the time of the next hit.
Sampras Forehand Volley:
Number of Forehand Volleys
Pre-Hit Speed
Max MPH After Hit
Pre Bounce MPH
Post Bounce MPH
End MPH
5
38 MPH
47 MPH
31 MPH
22 MPH
19 MPH
Sampras Backhand Volley:
Number of Backhand Volleys
Pre-Hit Speed
Max MPH After Hit
Pre Bounce MPH
Post Bounce MPH
End MPH
5
42 MPH
44 MPH
34 MPH
21 MPH
19 MPH
The initial speed of the overhead can exceed 100mph.
The Overhead
We were also about to capture and track the speed of 4 overheads, which rounded out a very complete picture of ball speed in Pete's game. The initial speed on the Sampras overhead approached the speed on his first serve, averaging 110mph on the 4 overheads measured, with a high of 118mph.
The Overhead We were also about to capture and track the speed of 4 overheads, which rounded out a very complete picture of ball speed in Pete's game. The initial speed on the Sampras overhead approached the speed on his first serve, averaging 110mph on the 4 overheads measured, with a high of 118mph.
Sampras Overhead:
Number of Overheads
Pre-Hit Speed
Max MPH After Hit
Pre Bounce MPH
Post Bounce MPH
End MPH
4
25 MPH
110 MPH
89 MPH
62 MPH
54 MPH
Summary
Due to the brilliant work by Nasif, this study gave us the first understanding of the general parameters of ball speed at the highest levels of pro tennis. As we already knew from the radar guns, points begin in pro tennis with serves traveling at 120mph or more. But the speed of a 120mph serve slows to around 55mph by the time of the return.
The average speed of Pete's forehand volley was 47mph.
The return in tennis can either increase or reduce the speed of the ball, so that it begins its flight back to the server at between 50-70mph. By the time the return reaches the server, the speed of the return has fallen into the 20-30mph range.
The initial speed on the groundstrokes ranged on average between 60 and 80mph, but again the ball slows to 30mph or less over the course of the flight. The volleys, hit in the air before the bounce, usually register 40-60mph coming off the racket, compared to abouty 40mph for the oncoming ball. Overheads can approach the speed of the serve, averaging well over 100mph and ranging up to as high as 120mph.
In the broadest terms we can say that the ball loses around 25-30% of its speed in tennis before it bounces, and another 20-25% after the bounce, for a total loss of about 50% between the hit and the bounce. Before the opponent strikes the ball, the shot can lose up to another 10% of its top speed. This means that over the flight of the shot, it loses at least 50% -- 60% of its total initial speed.
SUMMARY: Ball Speed
Shot
Pre-Hit Speed
Max MPH After Hit
Pre Bounce MPH
Post Bounce MPH
End MPH
Serve
----
120 MPH
87 MPH
62 MPH
54 MPH
Forehand Return
60 MPH
65 MPH
40 MPH
30 MPH
24 MPH
Backhand Return
48 MPH
51 MPH
32 MPH
21 MPH
18 MPH
Forehand
19 MPH
76 MPH
49 MPH
34 MPH
31 MPH
Backhand
17 MPH
69 MPH
49 MPH
32 MPH
28 MPH
Forehand Volley
38 MPH
47 MPH
31 MPH
22 MPH
19 MPH
Backhand Volley
42 MPH
44 MPH
34 MPH
21 MPH
19 MPH
Overhead
25 MPH
110 MPH
89 MPH
62 MPH
54 MPH
Teaching Implications
We think that the high shot velocity of pro tennis is one of the greatest difficulties for players--dealing with the frightening pace of a first serve from Andy Roddick or a huge forehand from Agassi, Safin, or Moya.
What our study suggests however is that the problem of timing the ball in tennis is more complex than that. Not only must the players deal with shots that routinely travel over 100mph, they must deal with radical changes in shot speed, changes that happen in fractions of a second and are in fact invisible to the human eye. A first serve in pro tennis decelerates from 120mph to 60mph or less in two thirds of a second, losing most of it's speed after the bounce in the critical instant a player actually makes his return.
Focus on the bounce and especially the path of the ball from the bounce to the hit.
So one problem is dealing with the deceleration, but a second equally difficult challenge is timing the ball when the range of initial speeds varies so much. they must deal with a very wide range of initial shot speeds. The ball may be traveling 120mph when it leaves the racket on the serve. But it's initial speed is only one third as high on a volley, around 40 mph. So the rhythm and timing of hitting a passing shot off a volley is radically different from that of a return.
This all suggests that the real key to timing is focusing on the changing speed of the ball. This means feeling the speed of the ball off the racket and then tracking the path as it decelerates. This process is most critical after the bounce when every shot loses the most speed.
Have you ever had the experience of consistently miss timing big serves? A common tendency is to panic, swing too early, and actually get of the ball. Knowing about the deceleration pattern gives you a key to overcome this. Because the ball loses so much speed when it hits the court, the returner has about 1/3 of his total time to make the return after the bounce.
By focusing on the ball trajectory and especially the critical component after the ball bounces, you can get in sync with the radical speed changes in the shot, and adjust your timing to the actual speed of the exchanges with your opponent, no matter what your level. This will work on the return where the ball speed is the highest. It will also help solve the problem at the other end of the spectrum--getting over anxious on the slow "easy" balls most people feel they should put away, but often miss.
The problem with the slow ball is that you have more time--more time to think--and especially, more time after the bounce when the slow ball slows down even more. Focus on watching the ball at the bounce--and especially, as it approaches the top of the bounce just before the hit. The results can be miraculous.
Here's one personal example of how it can work. After we first developed our results, I shared them with a fellow teaching pro and practice partner. Then we experimented with his return. He decided to key on watching the bounce on the court and the trajectory of the ball between the bounce and the hit. I served points in a game to 11. Although he usually returns well anyway, the first time he tried this key, it was amazing. He literally couldn't miss.
Usually I can get at least some free points against him with my serve--but this time none at all. He began ripping return winners on both first and second serves. It felt like I couldn't win a point on my own serve. "I had chills going up and down my spine," he reported. "I had total confidence I could make the return, but it went beyond that because I also felt I could do anything I wanted with the ball."
Try it for yourself, and let us know what you think. In the next article, we'll share our results from a similar study we did regarding the spin levels in pro tennis--something else that had never been previously studied.
John Yandell is widely acknowledged as one of the leading videographers and students of the modern game of professional tennis. His high speed filming for Advanced Tennis and Tennisplayer have provided new visual resources that have changed the way the game is studied and understood by both players and coaches. He has done personal video analysis for hundreds of high level competitive players, including Justine Henin-Hardenne, Taylor Dent and John McEnroe, among others.
In addition to his role as Editor of Tennisplayer he is the author of the critically acclaimed book Visual Tennis. The John Yandell Tennis School is located in San Francisco, California.
Source: tennisplayer.net archive — Ball Speed in Pro Tennis.docx (John Yandell teaching library, 2002-2022). Extracted and rendered as HTML for Tennis Future Lab.