Tuesday, November 13, 2007

Informal stroke speed survey of US tennis-Postscript

After the last post where I reported stroke speed measurements for high school varsity tennis players, I received a comment from a reader who raised some interesting questions that I felt would make the basis of an interesting post and becoming a starting point to share some other interesting stroke speed-serve speed, specifically-“phenomena” with you.

The two main questions raised in this reader’s comment were as follows:

Q1: You mentioned the wide range of skills among the high school players you measured. In a future post would you be willing to break out your data to show the difference in ball speeds between the couple best players and the run of the mill HS player?

A: The average fastest serve for three 5A State singles (#1 to #3) champions was 104.7 MPH.

The average first serve (all serves combined) was 94.5 MPH.

The average second serve was 73.9 MPH.

The serve speeds of these State high school singles champions are comparable to the speeds demonstrated by the typical Nationally-ranked 18-and-under junior boy (see the post titled “Memo to American college and junior players: Find another 30 MPH ASAP!) whose average first serve was 91 MPH and average second serve was 71 MPH.

Q2: Also, how much variance is there in the Division I ball speed data? Having measured, using a RADAR gun and video analysis, the serve speeds of several Division I male players (from one team), I'm surprised that the average first serve speed you found for Division I players is just 90 mph. My measurements found first serves to be on average more than 10 mph higher than that. My measurements were in practice, though, and not in competition so that might explain much of the difference. For instance, the players were simply hitting hard first serves, not mixing up the speed and spin as they do in matches.

A: The way I measure serve speeds, I record the speeds of individual serves and note what type of serve (flat, slice, topspin, or kick) was struck. So, when I report the average serve speed for either first or second serve, the speeds of all serve types are lumped together in that figure. So, on first serves, the faster flat serve speeds are averaged together with the slower slice and topspin serve speeds.

To address the comment, if we consider the average fastest serve speed for 1st serve for the D1 players I’ve measured, that average fastest 1st serve speed is comparable to the serve speed measurements made by the comment author (which I am now pretty sure that he measured the average fastest 1st serve speed) :

102.4 MPH (speed range was 81 to 120 MPH, mine) versus 100 MPH (his)

What’s also interesting to mention here is the trend I’ve noticed in the speed differential between the different serve types, i.e. flat versus slice and flat versus topspin/kick serves.

What’s interesting is that the speed differential between the different types of serves is relatively consistent even between the vastly different competitive levels from ATP pros down to 3.5 to 4.0 high school varsity players.

What I mean by this is:

The speed differential between a flat and slice serve is between 15 and 20 MPH at every playing level from the top ATP pros down through the NTRP 3.5 to 4.0 crowd.

For example, Andy Roddick’s flat serve averages typically averages around 135 to 140 MPH whereas his slice serve typically registers between 117 to 12 MPH. The typical NTRP 4.0 hits his fastest flat serve around 85 MPH, and his slice serve averages around 65 to 70 MPH.

The speed differential between a flat and topspin serve is typically 20 to 25 MPH for all playing levels I’ve measured so far.

FYI, if you are wondering what the difference between a topspin serve and a kick serve is, the easiest way is to distinguish them is to observe the direction the ball moves after the bounce.

A topspin serve bounces straight ahead or slightly toward the middle of the court relative to the original flight path of the serve, whereas a kick serve bounces toward the side fence (for right-handed servers, the bounce is toward the right side fence and for lefties, it’s toward the left side fence).

The speed differential between a flat and kick serve is typically between 25 to 30 MPH for all playing levels I’ve measured so far.

Why are kick serves slower than topspin serves? The answer is because of the slight difference in the arm swing path between the two serves—the additional sidespin applied to the kick serve by moving the toss further overhead decreases the forward momentum of the arm swing slightly resulting in a slightly lower overall racket speed (and therefore, (s)lower ball speed).

So, based on this consistent speed differential between the four main types of serves, I can essentially predict what the serve speed “profile” of a player is based on a single serve speed measurement. For example, if a player hits a kick serve at 75 MPH, the fastest flat serve they can hit will be in the range of 100 to 105 MPH. And if a player can hit a flat serve at 105 MPH, their slice serve will range from 85 to 90 MPH.

Are there exceptions to this “rule” of serve speed differential?

Of course there are… And the exceptions are of course, those players who can hit the absolute fastest serves (into the service boxes, of course)… i.e. the Andy Roddicks and Ivo Karlovics of the world, that is…

Roddick, for example, in the match he played today in the Masters Cup against Davydenko, routinely hit his flat first serve around 230 KPH or 143 MPH and his kick second serve around 160 KPH or 99 MPH….

This makes for a speed differential of 44 MPH!

But, I think you’ll agree, that in terms of on-court effectiveness, that 44 MPH difference doesn’t really have the same impact on Andy as it would for many lower-level competitive players whose maximum first serve speed is maybe, on a really good day, around 90 MPH. These are the same players who, after missing the box with their “90 MPH bombs”, then follow up with a massive 46 to 51 MPH topspin, “get it into the box” sitter that “quacks” as it flies over the net, to avoid the dreaded double-fault!

So, to close out this post, here's a memo to those of you who are standing, lifelong members of “Club 46”:

1) In order to hit an effective spin (second) serve, you need to generate the same amount of racket speed as you would on your flat serve to create both the necessary spin (for control) and ball speed (so your serve doesn’t quack and get smacked into all corners of the court by the returner).

2) If you want to hit a relatively effective topspin or kick serve, you need to be able to hit your topspin/kick serve around 70 to 75 MPH (air speed) to generate enough height and speed after the bounce to prevent most players from smacking your serve to all parts of the court without conscience.

3) Of course, if you can’t hit your flat first serve around 100 MPH, there’s basically no way (given the laws of physics governing the universe we inhabit) you can generate enough racket speed to hit a 70 to 75 MPH topspin/kick serve. So, if that’s your situation, may I suggest you start training with the SpeedChain to help you develop that extra 20 to 30 MPH you need to reach “Club 100”?


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At 7:57 AM, Anonymous Anonymous said...


Can you please comment on the breakdown of first serve types
among the different level players.

That is, what fraction of first
serves are flat, topspin, slice
etc. Also, as many comment "flat"
isn't really flat - how do players
choose the level of spin?



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