## Sunday, December 11, 2011

### Swinging Volley

My forehand backswing tends to be a bit long and "slappy". I've been trying to shorten the swing, but haven't had much luck.  Being almost 50 years old with 40 years of tennis under my belt makes any change tough.  One thing that seems to help is taking the ball out of the air from the baseline, a full-court swinging volley.  He's a compact version of my forehand doing just that.

Compare the length of that swing to any of the swings below.

### Forehand Balance and Swing Exercise

The exercise below, borrowed and slightly modified from Ray Brown, has been helping me make my forehand better. I'm trying to keep my racquet up until my legs begin to extend. I'm also trying to delay the forward swing of the racquet until my hips then shoulders have begun rotating toward the ball.

I'm trying to do this exercise a couple of times per day (backhand, too) for maybe five or ten minutes at a stretch. Then I try to feel this rhythm and timing in my swings when I hit balls. So far I feel like it's helping. At the risk of falling for the post hoc ergo propter hoc fallacy, I had never hit a 91 mph forehand before doing this exercise, but did afterwards.

### Better than B.E.S.T?

OK, so the study looked at complex pattern recognition not tennis strokes, but the little cartoon in the video intro shows a tennis player.  So...

Check this out.  "Learning high-performance tasks with no conscious effort may soon be possible."

Sweet.  Bring it on.

## Saturday, December 10, 2011

### Mike Agassi, B.E.S.T. Pioneer?

Below I wrote a bit about Brian Gordon's B.E.S.T. System for tennis mechanics. As the game of tennis has evolved, players have less and less time to execute their groundstrokes. Incoming ball speeds are getting higher and higher. In order to achieve high racquet speeds under extreme time duress, players have learned to shorten their backswings yet still produce high racquet speeds. They do this through what Brian calls "neuromuscular optimization".

Working with Rick Macci, Brian has developed a method, a progression, for teaching these optimal neuromuscular processes in young tennis players. I don't, yet, know the details of this teaching methodology. I hope to learn it in the next several months. In the meantime, I remembered the early training of Andre Agassi as Andre described it in his book, Open. Below I'll describe roughly what Andre described on pages 26-30 of that book. It sounds like Andre's dad, Mike, was following a B.E.S.T protocol, though the abuse Andre describes probably isn't part of Brian and Rick's system!

So how did Mike Agassi train Andre? First, the set-up.

Mike rigged up a ball machine to shoot balls at 110 mph down at Andre from an elevated position at the net. The placement and orientation of the ball machine did two things. First it deprived Andre of time. A ball shot at 110 mph from about 39 feet away was till traveling at 87 mph at the bounce. That's an average speed of about 145 feet per second. With Andre crowding the baseline, he had about 270 milliseconds from the time the ball left the machine until it hit the ground. That's very near the limits of human reaction times. Mike was definitely putting Andre under time pressure!

Second, the angle of the incoming ball forced Andre to take the ball on the rise. I don't know how high the machine was, but it's likely that the balls would still be rising as they hit the fence behind Andre if he didn't hit the ball. An ascending angle of incidence is the most difficult for applying topspin, meaning you need more racquet speed to put topspin on a ball ascending into your strings than on one descending into your strings. So Andre was forced to swing fast if he was going to put topspin on the ball.

Finally, Mike made the net six inches higher than standard so that Andre would be sure to clear regulation height nets. If Andre was going to get the ball over this higher net and down into the court at high ball speeds, he would need tremendous topspin to do so.

So what did Mike want Andre to do in these conditions? Well, first he wanted him to hit a million balls. Literally. Each year. Mike's goal was for Andre to hit 2,500 balls per day. That's 17,500 per week and almost 1 million balls per year. Brian Gordon says that extreme repetition is the only way to ingrain the neuromuscular patterns necessary to hit tennis balls well. Check. A million hits a year is a lot of repetition.

Second, Mike insisted that Andre take the ball early, take it on the rise. He wanted Andre to shorten his backswing. Always short. That's the modern evolution Brian talks about. No time for a "backswing the size of West Texas" he told me the other day. Check.

Mike insisted that Andre swing hard. "Hit the ball hard," he kept saying. So a short backswing while generating high racquet speed. Modern. Check.

Mike was constantly on Andre to "brush the ball", to hit topspin. "More topspin," Mike would yell. So by taking the ball on the rise, hitting hard, and brushing the ball for topspin, Andre had to swing very fast. Modern.

Mike was also intolerant of errors, particularly errors into the net. Mike would "foam at the mouth" when Andre would hit the ball into the net. He was unhappy with errors wide and long, too, but the errors into the net seemed to set him off.

Mike forced Andre to hit literally millions of shots under extreme time pressure, with short backswings, high racquet speed, while generating high ball speeds and spins. That's what the modern game demands of players. That's what the B.E.S.T. System seeks to train, if I understand it well enough.

I'm not endorsing Mike's methods for everyone. Andre clearly hated every second of this experience.  But it looks to me like Mike trained Andre well for the modern game of tennis. No question Andre learned what Mike wanted him to learn.

## Friday, December 09, 2011

### 100 mph Forehand

Huh.  The crappy pro from Case 2, Miikka Keronen, hit a 100 mph forehand today.  My 91 mph forehand from Wednesday looks wimpy.  No data on the revolutions per minute.  That will have to come later.

Does this mean we're qualified to teach high speed forehands?  To a moron, it means exactly that.

### Good Player to Good Coach Paradox

In order to perform motor skills well, especially under stress, the skill needs to be automated.  Conscious control of the process destroys performance.  Implicit learning, learning a player cannot articulate, appears to produce the most stability under stress.  So even conscious awareness of mechanics early in the process may not be the best way to learn.

So, a good player is an "unconscious" player.  How does John teach Tom how to do something that John does unconsciously?  One way is to simply demonstrate the skill and say "Do it like this."  If John goes beyond that demonstration and simple instruction, he's flying blind.

What's  most likely is that John will simply say things he's heard his coaches or other coaches say about how to perform a stroke.  Those things may or may not be correct and have nothing to do with John's skill as a player.

The only way for a good player to become a good coach, at least for automatic processes, is for the good player to learn all about mechanics and how people learn.

What advantage does the good player's skill offer in that process?  I'd say it's at least as likely to be a disadvantage as an advantage.

UPDATE:  Here's a nice little article from Psychology Today on unconscious competence and what conscious thought can do to performance.  It's based upon an anecdote, but an interesting one.

### B.E.S.T System

I am highly skeptical of the role of coaching, particularly when it comes to telling tennis players how to hit the ball.  I don't think we coaches know much about mechanics and I think we know less about helping players learn proper mechanics, if proper mechanics even exist.

There is one notable exception.  Brian Gordon has done extensive, quantitative, precise work on tennis mechanics.  He has the science education and more importantly the science experience to back up what he says.  Brian and Rick Macci have worked to put together a method for teaching highly advanced stroking techniques.  I haven't seen or evaluated their teaching progression, yet, but based upon what I know of Brian, I'm betting it's many steps ahead of what most of us coaches are doing.

I highly recommend you visit his site 3D Tennis Technologies and have a look around.  The best information on the B.E.S.T System is a bit hard to find.  Click the Enter Here button under the Information Zone.  See below.

## Thursday, December 08, 2011

### 91 mph Contact Point

I don't hit the ball particularly hard.  I generally hit a rally ball in the mid-50s mph.  If I want to be crazy steady, I'll drop that below 50 mph.  Part of that is because I live and play at 5300 ft above sea level.  Controlling the ball in this thin air isn't so easy.   If I want to push the issue a bit I'll up it to the mid-60s.  My big shots tend to be maybe 75 mph.  Nothing special about those ball speeds.  Many kids and all really good college and professional players can do better than that.  I've been clocked hitting over 80 mph in rallies on occasion, but that's pretty unusual for me.  Over 90 mph?  I'd never done that.  Until yesterday.

I hit a forehand yesterday that was measured with a RADAR gun at 91 mph.  That's very fast for me. For several minutes before cracking 90 mph I was hitting only in the low 80s mph due to a contact point not quite far enough in front of me.  Maximum racquet speed doesn't occur alongside the body.  It occurs at a point somewhat closer to the net.  Moving my contact point roughly foot forward gave me roughly 10 mph more.

So if you're having trouble hitting as hard as you think you should, check to see if moving your contact farther in front, toward the net, gives you a little more pop.

## Saturday, December 03, 2011

### Careful, Teaching Pros

Check out this forehand and tell me if you think the technique is sound based upon traditional forehand templates:

Looks downright crappy to me and everyone I've showed it to.  It elicits chuckles.  Nobody chuckles when it comes at them from the other side of the net!

If your concept of a technically sound forehand doesn't include what you see in that video, you'd better rethink your concept of sound technique.

Oh, and I'm not sure how you'd have to define "still" to say his head is still on any of the shots.

### Practice with Lesser Players

I just stumbled across a good post by Jeff Salzenstein.  It shows Colorado junior Max Roder hitting with ATP pro James McGee.  Both players are getting a good practice session.  Jeff's message is that you don't always have to hit with better players to get good practice.  That's obvious, but parents and kids way too often forget it.  They say they have to practice with better players to get better.  Not true.  If it were true, Roger Federer could not have practiced and improved over the last decade, since until recently there were no better players for him to practice with.  Even now, he doesn't practice with Djokovic and Nadal very often, if at all.  I guess none of those guys can improve.  Ha.

To amplify Jeff's message I thought I'd post a video of Dominic Inglot, former Virginia Cavalier and current ATP pro who was also in Colorado recently.  Dominic joined Miikka for a hit at The Ranch Country Club in Westminster.  Here's a few seconds of Dominic warming up (Sorry, no audio so don't adjust your speakers!).
Obviously Dominic is a way better player than Miikka, but Dominic didn't complain for a second.  He got a great workout and excellent practice.  He was grateful for the opportunity to come and practice while he was in town.

Don't be a snob and think you're too good to practice with someone.  Don't fool yourself into thinking that you can only get better by playing with better players.  The only way to get better is to practice.  So practice.

## Friday, December 02, 2011

### Rules or Exceptions?

"Watch the ball into your strings."

"Stay sideways." (usually said about a one-handed backhand)

"Stay down."

If these are rules, then I sure see more exceptions to them than I see great players following them.  Maybe these are rules to be broken.

## Monday, October 03, 2011

### Borg Vilas Shot Location Chart

I watched the video of Borg and Vilas that I had mentioned before (see this post) and charted approximately where each shot landed.  The result is the photo below.  The "R" was Vilas' return of serve.  The circled "83" was where Borg's approach shot landed.  Vilas missed that shot long to end the point.  Including the serve and return (which I didn't number), the rally was 86 hits, including the missed shot at the end.

As the shot chart shows, you can't have that long a point if you're hitting many balls close to the lines.
I was always taught, and still teach myself, that you want to keep the ball deep.  Seems like both guys wore out the service line area to me.  That isn't considered good depth.  But on this point, on this surface, with these balls, two members of the tennis hall of fame thought this depth was good enough.

I think this targeting is probably good enough for those of us not destined for the hall of fame.

## Sunday, July 10, 2011

### Discovery Learning

I just came across an article from The Mathematical Association of America, 1999, by Keith Devlin.  The article is called The Greatest Math Teacher Ever, Part 2.  A couple of excerpts that relate to teaching tennis the un-academy way.

He developed a method of teaching that became widely known as "the Moore method". Its present-day derivative is often referred to as "discovery learning".
Discovery learning is popular in tennis today, especially with younger kids.  Guided discovery is another name.  How's it work?
Part of the secret to Moore's success with his method lay in the close attention he paid to his students. Former Moore student William Mahavier addresses this point:

" Moore treated different students differently and his classes varied depending on the caliber of his students. . . . Moore helped his students a lot but did it in such a way that they did not feel that the help detracted from the satisfaction they received from having solved a problem. He was a master at saying the right thing to the right student at the right time. Most of us would not consider devoting the time that Moore did to his classes. This is probably why so many people claim to have tried the Moore method without success."
Can this work in tennis?  Probably not with large groups of kids, and probably not without a lot of hard work and planning by the instructor.  It's easy to tell kids how "load their legs", how to "make a unit turn", and how to move their arms on a serve.  What's not easy is to guide their discovery.
Plan well in advance and be prepared to really get to know your students. Halmos puts it this way: "If you are a teacher and a possible convert to the Moore method ... don't think that you'll do less work that way. It takes me a couple of months of hard work to prepare for a Moore course. ... I have to chop the material into bite-sized pieces, I have to arrange it so that it becomes accessible, and I must visualize the course as a whole -- what can I hope that they will have learned when it's over? As the course goes along, I must keep preparing for each meeting: to stay on top of what goes on in class. I myself must be able to prove everything. In class I must stay on my toes every second. ... I am convinced that the Moore method is the best way to teach there is -- but if you try it, don't be surprised if it takes a lot out of you."

### Shut Up!

As coaches and teachers we talk too much.  Just shut up and let the students learn.

“The best way to learn is to do; the worst way to teach is to talk.”  -- P.R. Halmos

That's the first sentence of an article called "The Teaching of Problem Solving"Paul Halmos was a mathematician.  He may as well have been a tennis coach.

Hat tip to Seth Roberts for mentioning the Halmos article on his blog.

## Thursday, July 07, 2011

### What a Drag

When a ball moves through the air a force called drag slows the ball down.  The drag force acts in the opposite direction of the ball's movement.  Here's the equation for drag force:

F=Cd*A*d*(v^2)/2

I got this equation from page 362 of The Physics and Technology of Tennis by Brody, Cross, and Lindsey (BCL).  In the equation, Cd is the drag coefficient of the ball, A is the cross-sectional area of the ball, d is the density of the air, and v is the ball's velocity.  BCL give values of 1.21 kg/m^3 for d (sea level), and 0.55 for Cd for a new tennis ball.  The ball's cross sectional area is pi*r^2, where r is the radius of the tennis ball (roughly 33 mm).

Having fun yet?

There's an even more fun equation a few pages later (p. 388) in the appendix on ball trajectories.  In this equation we've ignored the relatively minor vertical component of a ball's velocity and are only looking at the horizontal component.  When you hit a ball toward the other side of the net, how much does it slow down?  Since I'm interested in the effects of lower density air on the flight of a tennis ball, these are the equations that I care about.  Here's the equation:

t = (e^(k*Cd*x)-1)/(k*Cd*v0)

This tells us how long it takes (t, measured in seconds) a tennis ball (with a coefficient of friction Cd) to travel a particular distance (x, measured in meters) when moving through air for a specific initial velocity (v0, measured in meters per second).  In addition to the terms just mentioned we have two other terms to define.  The term e is simply the base of the natural logarithm.  The term k is a bit more complicated.  We'll use an equation from BCL (p. 387) to define k,

k=(d*pi*R^2)/(2*m)

Argh.  More undefined terms.  We used d above, and it's the density of the air.  R is just the radius of the ball, roughly 33 mm (.033 m), and m is the mass of the tennis ball (57 g or 0.057 kg).  Pi is pi.

So for a sea level standard tennis ball,

k = (1.21*pi*0.033^2)/(2*0.057)
k = 0.0363 m^-1

Back we go to our more interesting equation, armed with a value for k,

t = (e^(k*Cd*x)-1)/(k*Cd*v0)

Let's plug in some numbers and see how long it takes a ball hit at 70 mph to travel 80 ft.  We're imagining a player standing a little bit behind his own baseline, perhaps, hitting a forehand to roughly the far baseline.
We have to convert feet to meters and mph to m/s.  Google will do that for us, spitting out 31.3 m/s for 70 mph, and 24.4 m for 80 ft.

We already said that Cd for a new tennis ball is 0.55 according to BCL.  Let's plug and play:

t = (e^(0.0363*0.55*24.4)-1)/(.0363*0.55*31.3)
t = 1.004

Let's round that to 1.0 sec.  How cool is that?  Must have picked those numbers to come out that way!

So how much does the air slow down a ball moving horizontally?  Well, without air we know how long a ball leaving the racquet at 31.3 m/s would take to travel 24.4 m by dividing the second number by the first.

t = 24.4/31.3 = 0.78 sec

So this forehand took 28% longer to go 80 ft through air than though a vacuum.  By playing at sea level instead of outer space (or the moon), we bought ourselves 0.22 sec to get to this ball.

Now for the big question:  How much time do we lose in Denver?

The density of air in Denver is not 1.21 kg/m^3.  It's about 0.84 times that, or roughly 1.02 kg/m^3.

Back to our equation.  Where does the density of air come in?  It comes in via that pesky k.  Recall

k=(d*pi*R^2)/(2*m)

There's d in there.  So we need to recalculate k for Denver rather than sea level.

k = 1.02*pi*0.033^2/(2*.057)
k = 0.0306

Should we call that kd for Denver?  Back to the time equation:

t = (e^(kd*Cd*x)-1)/(kd*Cd*v0)

Plug in some numbers and let Google give us a value for long it takes a 70 mph forehand to travel 80 ft in Denver:

t = (e^(0.0306*0.55*24.4)-1)/(0.0306*0.55*31.3)
t = 0.964 sec

We've lost some time by moving up to Denver.  But not much.  We've only lost about 0.036 sec.  That's a loss of 3.6% (again note the easy math because of the 1.0 sec transit time at sea level!).

Trouble.  In earlier posts, I've been assuming that the ball slows down 16 to 17% less slowly in Denver than it does at sea level.  All good players say the ball travels faster through the air up here than down there.  What gives?

What gives, indeed!

It could be completely due to the extra bounce of the ball.  The high-altitude balls do tend to bounce a bit more up here than balls bounce at sea level.  That 9% livelier ball, plus this roughly 4% less time due to thinner air, may add up to a difference that we all notice.  If you can simply add these effects, then 13% or so livelier game probably is a big deal.

Since I screwed up so badly on my prior estimation of the effects of our air on the ball, I'll keep my mouth (or fingers) shut until I've given this some more thought.

## Wednesday, July 06, 2011

### A New Can of Balls

UPDATE: The other tests I referred to in this post were flawed. I dropped balls from a lower height and assumed, incorrectly, that the coefficient of restitution would be the same as if I'd dropped them from the 100 inch ITF specification. Turns out the COR decreases as velocity increases. So the prior tests over-estimated the 100 inch rebound.

I just opened a new can of Penn Championship High Altitude tennis balls.  The balls had been sitting at 68 F degrees for a week.  They averaged about 57 to 58 inches of rebound when dropped from 100 inches (68 F degrees).  That's within the sea level specification of 53 to 58 inches.  Nice.

But I've tested other balls that rebounded 62 inches.  Well, that makes sense.  The specification range for high altitude balls is 48 to 53 inches at sea level.  So that means my range at 5,300 ft is roughly 57 to 63 inches.  So if I happen to get a high altitude ball that's at the low end of the specified range, I'll have a ball in Denver that is within the sea level specification.

That's just luck, of course.  We're still stuck with balls that, on average, exceed the mid-range of the sea-level specifications by about 8%.  Since the balls slow down less up here once hit, that's a big problem.

I've tested roughly 9-month-old balls and they're at the bottom end of the sea level spec for rebound.  Nobody seems to like the sound and feel of those balls up here.  Maybe nobody likes balls at the bottom of the spec at sea level either.  I don't know.  But up here, balls that meet the rebound spec, still leave us with a game that's about 16% faster through the air.

Lighter balls slow down more, but they feel odd, too.  Balls with fluffier naps may be the answer.

The Prince Tournament ball fluffed up a lot.  Maybe I'll have to track down more of those.

In the meantime, I still think the Stage 1 "green" ball is a better compromise than the current high-altitude ball.  We used them for an "elite" junior group today and the play was more fun, I thought.  Then I hit with some on an artificial grass court and again the play was fun.  It's nice to have time to set up and it's nice to be able to take a cut at the ball.  Both are not too common at this altitude.

## Monday, July 04, 2011

### What's Wrong With French Tennis?

A friend recently attended a USTA High Performance Coaches Workshop.  At the workshop he was told that France has 10x as many juniors than the US playing tournament tennis.  The message was that we're doing something wrong in the US.  Could be.  Probably.

But the most recent ATP World Tour rankings show the US with nine men in the top 100, while France has eight.

Spain leads the way with fourteen.  No word from the USTA on how many juniors play tournaments in Spain.

Once proud Sweden has one, same as Australia and Great Britain.  Fewer than Kazakhstan.

Maybe it's a prosperity problem.  More prosperity means higher opportunity cost of becoming a tennis champion.  You'd think rich countries would produce more great players since it costs a lot to become great at tennis.  But maybe it doesn't cost much to become great at tennis and the more important factor is how much are you giving up to become a great tennis player.

Maybe rich countries can afford more coaching and more coaching ruins players.

## Friday, July 01, 2011

### Defense, Defense

The two best defenders in the draw have advanced to the 2011 Wimbledon gentleman's final.  Nadal beat Murray (the third or fourth best defender) in four sets in one semi, while Djokovic beat Tsonga (not a very good defender) in four sets in the other.

A quick and crude look at the stats shows simply that the guy with the least unforced errors advanced in each match.  Nadal had just eight unforced errors in for sets.  Murray had forty-four.  That's an enormous advantage for Nadal.  Djokovic made just fourteen unforced errors in his match compared to thirty-four by Tsonga.

This doesn't mean that Nadal and Djokovic were just pushing, far from it.   Nadal hit seventy-four winning shots (winners plus forcing Murray errors) and Djokovic hit 107 (winners plus forcing Tsonga errors).  Dokovic's ratio of winning shots to unforced errors was 7.6 to 1.  That's awesome.  But not as awesome as Nadal's ratio of 9.25 to 1.

The losing semi-finalists had much worse winning to losing shot ratios, naturally (3 to 1 for Tsonga and 2 to 1 for Murray).

Neither Nadal nor Djokovic hit as many outright winners as their opponents today, but both obviously hit a lot of winning shots, in Djokovic's case, more winning shots than Tsonga hit.

The defenders won, but they had to win the matches.  Their opponents didn't just hand them the matches.  You wouldn't expect that in a Wimbledon semi.  But for players well below this level who do not aspire to this level (and if you aspire to this level you don't need my advice!), the simple take-home message is the guy who gave away the fewest points won both matches.

### Over Training?

Now that it's clear we are playing a much tougher, faster game of tennis at high altitude, is it possible we have an advantage up here when we go to lower altitudes?  Since the ball comes at us much faster and bounces much higher, are we training ourselves to play higher speed, higher quality tennis?  Since we're forced to hit through much smaller vertical acceptance windows, are we becoming more precise than our low-altitude counterparts?

I think the answer is yes to all the above.  I think players ages about 13 to 20 years old have a hard time learning and mastering the game up here, because it's so much harder.  We don't see many great players who were born, raised, and trained exclusively at high altitudes, so I think it's reasonable to assume that the thin air hinders development for the reasons I've discussed in previous posts.  But...

If you mastered the game at lower altitudes, learned to be patient, develop points, play with high racquet speed generating high ball velocities and spin rates, then at some point you may benefit from playing at high altitude.

Those of us who've lived up here for a long time certainly have adjusted to the game.  It no longer feels crazy to me like it did when I came here thirty years ago.  If I play a bit at lower altitudes, the ball seems hard to control at first when I come back, but it's nothing a few minutes of hitting doesn't cure.  And it's hard for me to get any depth on the ball at first down at sea level, but again, it's nothing that a little bit of hitting won't cure.

So, if we can avoid the impatience that this altitude can breed, if we can avoid the illusion that we can end points quickly, and if we can train ourselves to go for balls we don't think we can get to,  I think we can benefit from playing up here.

I think we've had plenty of players do well in senior age group play on a national basis.  That's evidence that playing up here can make you a better player at sea level.

I still think we need to replicate the low-altitude game with a much slower ball at this altitude.  But it's nice to know we can benefit from cracking open a can of jumpers when we feel the need.

## Wednesday, June 29, 2011

### Ball Test

UPDATE 10/4/2012: The tests below failed to take into account the effect of changing coefficient of restitution (COR) with respect to velocity. Therefore, these tests, conducted with a drop height of less than 100 inches, do not reflect the rebound characteristics required by the ITF specifications. My simplifying assumption, that I could drop the balls from lower heights, was wrong.

Science is about experiments.  Enough theorizing.  I went to the BRG Lab and tested some tennis balls.

I didn't have the skill or the inclination to set up a standard testing station, so instead I picked a convenient height -- the BRG water heater -- and measured it.  57.5 inches.  My thermometer said it was 68 F degrees, exactly as specified by the ITF.  According to the ITF specifications (click), a ball dropped from 100 inches should rebound between 53 and 58 inches at sea level.  I'm at about 5,300 ft, but I want to find a ball that rebounds 53 to 58 inches up here to replicate what sea level players experience in terms of the ball's bounce off the ground.  A rebound height of roughly 30.5 to 33.5 inches from my lower drop height approximates the sea level specs (I did some algebra to find that range).

First I dropped a two-day old Penn Championship High Altitude ball.  The ball rebounded roughly 36 inches in three drops.  That's about 12% above the spec range midpoint.  In line with my previous predictions.

Next I dropped an old Penn Championship High Altitude ball.  I opened this ball's can in October of 2010 (it's 6/29/2011 today).  I dropped this ball twice and it rebounded about 31 inches and 32 inches.  Nicely in the spec.

Then I dropped a year old (at least) Tretorn FunLite ball.  This is a "green" transition ball made for U10 tennis.  It is supposedly a 25% reduced bounce and flight ball.  This ball rebounded 32 inches.  Nicely in the spec.

Then I dropped a Penn Control+ green dot ball.  Like the Tretorn FunLite, this is a 25% reduced bounce and flight ball.  This ball rebounded roughly 32.5 inches.  Within the spec range.

Geez, no wonder my low-altitude friends say those transition balls seem "less weird" to them than our normal high-altitude balls.

So which ball should be the preferred ball for tennis at my altitude?

UPDATE:
I tested another ball today, the Wilson Green Dot reduced speed, transition ball.  Like the Penn Control+ and the Tretorn FunLite, this ball is marketed as a 25% reduced speed ball.  The first time I tested this ball, it really hopped, coming in at 62.5 inches, dropped from 100 inches.  That's way too high.  But the ball was really hot.  After being out of its can for about six hours, and out of the heat for about four hours, the ball rebounded 54.5 inches.  Nicely in the 53 to 58 inch spec range.  I'll test it again tomorrow after it's been at 68 F degrees for 24 hours [UPDATE:  No change from night before, i.e. roughly 54.5 inches].  This ball has a mass of 49 grams, so it should slow down nicely as it moves through our thin air.   Good possibility for replicating low-altitude play at my altitude.

## Monday, June 27, 2011

### High-Altitude Tennis Balls

The ITF and USTA standards for high altitude play specify a ball that rebounds from 48 to 53 inches when dropped from a height of 100 inches at sea level.  The standard for normal balls, that is low-altitude balls, is for them to rebound from 53 to 58 inches when dropped from 100 inches at sea level.

Since the high-altitude balls have the same mass and volume, I assume that this means that pressurized high-altitude balls are simply pressurized less so that they rebound less.   The standard calls for a high-altitude ball to rebound roughly 91% of the low-altitude ball at sea level.  Since the air at a mile high has roughly 84% of the pressure of air at sea level, we can assume that the high-altitude ball will rebound higher at a mile above sea level than a normal ball will rebound at sea level. [See UPDATE below]

This is moronic. [It would be moronic if true. It's not. See UPDATE below.]

The only accommodation made in the rules for high-altitude play is for a ball that bounces roughly 10% higher than a standard ball does at low altitude.  The ball has the same nap, volume, and mass.  So not only does the ball come off the racquet 10% faster than a ball does at low altitude, it slows down over 16% less slowly.

Oh, and when our rocket ball hits the ground remember it will bounce 10% higher than what our low-altitude counterparts are dealing with.

No wonder we don't develop any good players up here.

Why in the world isn't the standard for the high-altitude ball, when tested at sea level, to rebound to a height that is more like 84% of the sea level ball?  That ball, when brought to Denver, for example, would at least bounce the same as a ball at sea level (the pressure differential between the inside and the outside of the ball being the same).

Too bad the bigger balls failed and disappeared.  Those would be an improvement, though they'd clog up ball machines and tubes.  Probably wouldn't fit through the bottom slats of hoppers, either.  Oh well.

We're screwed up here.

UPDATE. It turns out that there's more, or less, to rebound than the pressure difference between the inside and outside of the ball. Probably the rubber material plays a role, too. So, in testing some balls more recently, I've discovered that the high altitude ball, which rebounds between 48 and 53 inches when dropped from 100 inches at sea level, does in fact rebound between 53 and 58 inches when dropped from 100 inches at 5300 ft above sea level.

## Thursday, June 23, 2011

### Zen Tennis

Can tennis be a meditative experience?  I think so.

Timothy Gallwey's The Inner Game of Tennis and Inner Tennis: Playing the Inner Game were very successful in their day.  They helped me for a time.  I was a nightmare on the court 99.99% of my competitive career.  The 0.01% of the time when I wasn't a nightmare I owe to Tim Gallwey.  I had some of my best results during the 0.01% of the time I was under his spell.

During my last summer in junior tennis I read Timothy Gallwey's Inner Game of Tennis.  The book got me to relax and just play the game, accept what happened.  Before and after that summer, I was a terror on the court.  I was fiercely competitive.   I was extremely hard on myself.  I would do anything (short of cheating, which luckily I outgrew before I discovered tennis) to not lose a match.  If I lost I was furious.  Points.  Games. Matches.  Any loss, any poorly struck shot, drove me into a blind rage.  I made Nastase, Connors, and McEnroe look like altar boys.   But the summer I read Gallwey's Inner Game I became calm.  I mean really calm.  No fits of rage.  No tournament directors wishing I'd die a painful death.  I even recall some officials in St. Louis that summer saying how great I was to have in their tournament (I lost in the feed-in consolation finals to my friend, Isaac Menda, a much better clay court player than I was).  Boy was that rare.  I digress.

So, can tennis be a meditative game?  I think it can.  I think my experience shows it can.  I finally achieved some national success the summer I wasn't a nut.  I think Bjorn Borg's success shows it's possible.  Borg wasn't some barefoot, zen wack-job, but he wasn't a rager, either.  He didn't complicate the game.  He just tried to get the ball back one more time than his opponent.  He ralaxed in the rallies.  He tried like hell to win.  He ran down every damn ball with everything he had.  He'd play a point all day if he had to.  But he accepted what happened to him.  At least that's how he seemed to those of us who watched him play.  He walked away from the game when he no longer wanted to play.  Amazing.

I've always thought of tennis as boxing without the blood.  Two men enter the cage and one man comes out.  The other guy goes home.  I loved that about tennis.  But there's another way to think about it.  The zen way.

Can the zen way work?  Borg's career indicates it can.  At lower levels, I know it can.  At lower levels, players lack the skill to win many points.  Most points are lost.  By lower levels, I'm talking about levels of tennis below the upper echelon's of men's Division I college tennis.  Players on top 50 teams can win points.  They win matches.  But below that level of skill, vastly more points and matches are lost than won.  That means a player that simply relaxes into the rallies, tracks balls down and gets them back in play, is going to "win" many more matches than he (or she) loses.  What's the best mindset to play this sort of tennis?  The zen mindset.  Just relax and let the points happen.

The key to rallying the ball is a quiet mind.  If you feel the need to press the issue, to force your opponent into errors or to hit winners yourself, you'd better be damned skilled if you want to win.  If you want to "win" matches by letting your opponent lose, you'd better be able to quiet your mind and be patient in a rally.  You'd better be accepting of your opponent's winners.  Most competent players can hit a lot of winners.  They just can't hit enough of them to beat a competent opponent.  Not below the upper levels of men's D1 tennis, or below the very best junior players in the world.

I don't know if zen tennis is the most exciting hobby in the world, but relishing in the act of running down shots and sending them arcing back over the net can be fun and relaxing.  It can also be very successful, I think.

Give it a try and see if you aren't way more successful than you think you'll be.  It's worked for me and I think it worked for Borg.  It can work for you.

### Tennis's Siren Song

To hit a tennis ball hard is pretty easy.  To hit it pretty hard and get it in is also pretty easy.  To hit it pretty hard and get it in often enough to play good tennis is very hard.  Let's go to the numbers.

If you're a basketball player and you make 85% of your free throws, you're considered among the best of the best.

If you're a baseball pitcher who throws strikes 85% of the time, you're better than good.  You're great.

If you're a young hockey goaltender and you save 85% of the shots you face, you're darn good.

How about if you play tennis and can hit the ball in the court 85% of the time at a given speed and spin?  How good are you?

Well, if the ball doesn't come back much, then you're awesome.  But nobody can hit a ball in the court 85% of the time and have it not come back, unless we're talking about overheads and volleys struck just above the net!  Nope, any shot that you can put in the court 85% of the time is likely to come back most of the time, too.

So, what does that mean for your rallying?  If you and a partner decide to rally back and forth, hitting shots that each of you can get in 85% of the time, what is the probability that you'll succeed on any given attempt?  In order to execute a ten shot rally, you and your partner need to hit ten consecutive shots in the court.  That means you need to multiply 85% times itself ten times.  We write that 0.85^10 (the "^" being the way of denoting an exponent).  Whipping out my trusty calculator and entering 0.85^10, I get roughly 0.197.  That means you have less than a 20% chance of hitting ten balls in a row with your partner.  You'll need to try, on average, five rallies before you'll get to ten consecutive hits.

That's not very good.  What if you want to make it to twenty hits? You're down under a 4% chance of doing that.  You'll need to try 25 times for every successful 20-ball rally.

It's pretty alluring to hit a ball at a velocity that you succeed at 85% of the time.  Frankly, I think it's pretty alluring to hit the ball at a velocity that I succeed at 75% of the time.  The bad news is that I'm likely to make 10 consecutive hits (forget my opponent) only about 5% of the time at my 75% success rate pace.  That's horrible.  By choosing to hit at a pace where I can get the ball in three out of four shots, I'm going to lose to anyone who can make me hit more than three shots a point.  Why?  Because 0.75^3 = 0.42.  I'll succeed in making three consecutive shots less than half the time.  That's a losing proposition in tennis.

No wonder pushers win.  They just put the ball in play and let the Siren Song of high-paced tennis draw their opponents into failure.

### Wall Practice

I've written about this before, but I thought I'd mention my wall practice yesterday and compare it to how most kids practice.

I grabbed a 75% compression ball and stood roughly 20 - 25 ft from a backboard that had a line at net height and a 9 sq ft square, the bottom of which is 3 ft above the net line.  I hit soft topspin forehands and backhands up into the square for 3 minutes.  I counted 96 hits.  I got a quick drink and repeated this exercise with a high-altitude ball.  Same number of hits.  All but a couple of my hits were in the square.  None were below the net line or over the fence.

I got another drink and did a 10 minute round with the 75% compression ball again.  That ball moved more in the wind, bounced a bit more erratically, so I thought it would be more challenging.  I didn't count the hits this time, but my distance from the wall and hitting pace were the same as the first two rounds, so I must have hit roughly 320 shots in the ten minutes.  Again, no shot "missed" or bounced twice and all but a handful of shots went into the square.  I probably failed to put topspin on three or four balls during that time.  I just brushed up on the ball, lifting it with topspin into the 3' x 3' square.

So in 16 minutes of hitting, I hit roughly 500 shots.  Tack on a couple of minutes between rounds and we'll call it 20 minutes total, that's as many shots as I would hit rallying non-stop with a partner who never misses in about 35 minutes.  Basically I was able to cut my practice time in half.

Of course, hitting gently against a wall isn't the same as hitting gently on a court.  But it does help me do what all great players do, that is make solid, consistent contact between the racquet and the ball.

Could a coach feeding balls to a student get the results that my wall practice got?  Would a coach tossing or hitting balls to the student be as good for consistent ball contact as my wall practice?  Would the coach's admonitions to "move your feet", "load on the outside leg", "make a unit turn" etc enhance or degrade the feedback I got by hitting balls into that wall?

When I watch players hit fed balls, I see a radically variable error rate.  Some kids don't miss much.  Most kids miss a ton, especially relative novices.  This high error rate trains failure.  The wall rally trains success.

### QuickStart Tennis League

It's time to ditch the model of tennis lessons and clinics, especially for little kids.  This summer we started a QuickStart tennis league in our area.  We have three clubs participating and we've divided the league into three divisions: red, orange, and green.  The red plays on the red court (36') with the red balls and smallest racquets.  These kids tend to be age 7 or younger.  The orange plays on the orange court (60') with small racquets.  These kids are roughly 8 and 9 years old.  The green plays on the green court (78') with the green (75%) balls.

The league has been a huge success.  The kids love it.  They move from club to club each week, with one division at each club.  The kids wear the t-shirts of their club.

At the same time, we've struggled with our QS lesson groups at our club.  The kids in those groups are not doing the league, for the most part.  The kids in the lessons are motivated about like you'd expect kids to be in lessons.  Not.  We do the best we can to keep things fun and lively, but the kids like the lively games, not tennis.  They have no desire to learn to play tennis because they're just in lessons, without the carrot of matches or tournaments.  That's no way to run a junior program.

All other sports, well the popular ones, have leagues.  Kids sign up for a baseball league.  They sign up for a basketball, hockey, football, or soccer league.  They get put on a team.  The teams have practices and games.  That's the model we need for U10 tennis.

Scrap the b.s. "lessons".  Lessons suck.  They kill the joy of any activity.

## Wednesday, June 22, 2011

### Shot Tolerance

So how many balls are you willing to hit to win a point?  As many as Borg and Vilas?

FYI, I estimate their average ball speed in the 50 – 55 mph range.  Different era, but how many of our junior players hit the ball better than Borg and Vilas?  For those of you at high-altitude, keep in mind that for an equivalent acceptance window you'd have to keep your ball speeds in the 45 – 50 mph range.  That feels darn slow if you're any good.  But can you hit fifty or more balls in a row, stress free, hitting harder than that?

## Tuesday, June 21, 2011

### Pay Juniors

What can the USTA do to produce world class tennis players?  I vote for paying junior players.  Take the budgets dedicated to all the training centers and high-performance coaches and spend it on juniors.  Spend it in two ways.

First, go back to covering the expenses of endorsed juniors for the bigger national junior tournaments.  Use sectional and USTA funds to cover the airfares and the hotel expenses of juniors who qualify for national tournaments based upon their results in their sections.  The only way to earn this money will be to play in, and succeed in, sectional tournaments.  Each section will get an allotment of spaces in the national tournaments, like when I was a kid (my section got one or two slots -- we weren't very populous and we weren't very good!), and will endorse and pay the expenses for those kids.

Second, award prize money to the top finishers in those national tournaments.  With feed-in consolation at all the events, paying the top finishers in all the events should not be difficult.  I'd pay the winner, runner-up, third, fourth, fifth and sixth place finishers for sure.  That would cover the winner and runner up in the back draw.  I'd probably also pay out another half a dozen or more places.  I think the winner could get $5,000 or$10,000, with the rest of the money scaled down.  I think that would generate some great competition.

My inclination is to only pay prize money for the biggest national tournaments, but I'd be open to the idea of some lesser prize money at the national open tournaments, too.  The reason I'm hesitant to pay the national opens is that there are too many of them.  I want the best players to play each other and I want them to do it often with a lot on the line.

Having the best US juniors play each other in big, national tournaments six to ten times a year seems like the best way to develop great players.

In between those tournaments, the best players will be able to spend their prize money on coaching or academies or travel to other tournaments.

Oh, I realize that this scheme would jeopardize the amateur status of US juniors.  So what.  Sham amateurism was killing tennis before 1968.  Open tennis has been wonderful.  Sham amateurism was ruining track and field.  That scam ended many years ago.  If the NCAA has a problem with this, they can solve the problem with one simple rule change:  professional players are welcome in college tennis.  End of problem.

Do colleges care if drama or music majors accept pay for performance?  I didn't think so.

### The Fate of the Server

Interesting article in the Wall Street Journal today on big servers and Wimbledon (click).  The best part is about the young Canadian, Raonic.

## Monday, June 20, 2011

### Freedom to Learn

I'm quite sympathetic to the views expressed by Peter Gray in these posts at Psychology Today.  I was never a fan of school when I was a K-12 student.  I took to it more when I was in college.  But I've grown even less fond of schooling as I've grown older and wiser.

This relates broadly to tennis as more and more people try to learn tennis in "academies" and other school-like settings.  I think that is a very bad trend.

### The Human Nature of Teaching

For you tennis teachers, players, and parents out there, here (part 1, part 2part 3) is a very interesting three-part series of essays on teaching in hunter-gatherer societies by Boston College psychology professor Peter Gray.

## Sunday, June 19, 2011

### Margin of Safety

"Margin of safety, the three most important words in investing."
Those are the words of Warren Buffett, the most successful investor in history.  Buffett became the richest man in the world by compounding an initial investment of $100 in the Buffett Partnerships to a fortune exceeding$50 billion.

"I've had people hand me more major championships than I've won."

Those are the words of Jack Nicklaus, winner of eighteen professional major golf championships, most in history.

So how do we play tennis with a margin of safety so that people will hand us matches, and maybe even major championships?

Let's "invert, always invert" in the words of the great mathematician Carl Jacobi.  How do we play low margin of safety tennis?

Well, to play low margin of safety tennis, we should aim close to the boundaries, that means hit low, deep, and to the sides.  That way we bring the net (low), the baseline (deep), and the sidelines (sides) into play.  All three of the places our shots can miss are in play.

What else?  Well, we should definitely hit hard.  Our acceptance windows get exponentially smaller the harder we hit, so high pace is key to low margin of safety tennis.

How about spin?  Well, we should avoid topspin at all costs, since that increases our acceptance window.  Slice is the best since that reduces our acceptance window the most.  If we can't slice the ball for some reason, flat is the next best thing.

Where should we stand for groundstrokes?  The closer in the better.  Our acceptance window increases as we move back behind the baseline, so try to hold that baseline and hit balls inside the baseline whenever possible.

Since we're inside the baseline, should we take the ball on the rise?  Absolutely, for two reasons.  First, taking the ball on the rise makes it very hard to hit topspin, which we noted above we definitely want to avoid.  Second, if we take the ball on the rise, especially just after the bounce, we can strike the ball down around our knees, or even lower if we can short-hop the ball.  The higher we strike the ball the larger our acceptance window is and we want to keep that window small to keep our margin of safety as low as possible.

How about changing the direction of the ball?  Change it.  Sending the ball back where it came from dramatically reduces left-right errors, again increasing the margin of safety.  Changing the direction from a cross-court ball that crosses your body by going down the near line is a great way to reduce your margin of safety.  And since you're going down the line, make sure to hit the ball very hard.  The high velocity ball down the line has a much smaller acceptance window than a ball played back cross-court or to the middle.

So, there you have it, a great recipe for playing low margin-of-safety tennis.  Hit balls low and hard to the deep corners, using slice or no spin.  Make sure you take the ball early, on the rise, and inside the court, if possible.  Take cross-court balls down the line.

To play high margin of safety, just invert the above paragraph.

There are many ways to tennis heaven, and playing low margin-of-safety is one of them, though I see many more successful high-margin-of-safety players at all levels.  But you gotta do what you gotta do.  My guess is if you love the low margin game, I'll be seeing you in the back draw.

## Friday, June 17, 2011

### Vertical Acceptance Window and Mile High Tennis

In order to hit the ball over the net and have it land on or before the far baseline, the ball must leave the racquet within a certain "vertical window".  From simulations done by Howard Brody (Tennis Science for Tennis Players, pp 99-100) I noticed that this window gets cut in half (shrinks by 50%) as you increase your initial ball speed from 56 mph to 67 mph for balls hit at sea level.  That means if you avoid the sidelines, good advice in rally situations, you more than double your chances of getting the ball in if you hit the ball 56 mph rather than 67 mph.  A 67 mph shot is getting pretty fast for most people, but it's not crazy fast.  I can hit a ball over 80 mph and I'm not a big hitter at all.  Most juniors around here can hit forehands 90 or 100 mph.  Yet, I see almost nobody at my mile-high altitude sustaining rallies in the 60 mph range.  Why not?  Do we suck?  Hardly.

Our air is less dense than air at sea level, 0.84 compared to 1.00 roughly.  To compensate for this, the ITF allows us balls with reduced compression, 9% less than standard balls.  That means the balls bounce a bit lower and come off the racquets a bit slower.  So they make it harder to hit the ball 56 mph or 67 mph in the first place.  But the balls are otherwise the same as low-altitude balls, same size, mass, and nap.  So once we hit them, they do not slow down as quickly in our air.

A ball with an initial velocity of 47 mph in Denver will have the same vertical acceptance window as a 56 mph ball struck at sea level.  A ball struck at 56 mph in Denver will have the same vertical acceptance window as a ball struck at 67 mph at sea level.  Our vertical acceptance window gets cut in half at relatively slow ball speeds.  It's just not that hard to hit a ball 56 mph.  Almost anyone can do that.  But due to our dramatically reduced vertical acceptance window, very few people can control a rally at that speed at high altitude.

The window shrinks even more quickly as the speeds get up over 67 mph at low altitude or 56 mph in Denver.  Very, very few people can sustain a rally with initial ball speeds over 70 mph at low altitude. I have timed many rallies between very good players (tour and college level men and women) and in those rallies, initial ball speeds above 70 mph were rare.  None of those 70 mph rallies were at high altitude.

It makes sense then that good players in Denver would have enormous trouble sustaining rallies with ball speeds above 60 mph.  No wonder tour pros avoid high altitude.  They're not good enough to play here!

## Tuesday, June 14, 2011

### Satisfactory Results

To achieve satisfactory investment results is easier than most people realize; to achieve superior results is harder than it looks. – Benjamin Graham

Benjamin Graham, the father of security analysis and the author of The Intelligent Investor, may as well have been talking about tennis. I think it's surely true that to achieve satisfactory results, that is, to win more than you lose, to become pretty darn good at the game, is easier than most people think. Why do I say this? Because tennis matches at all but the highest levels are lost, not won. That means all you have to do to win at most levels is get the damn ball over the net and into the court. That's easier than most people realize, if they make that the goal.

But they don't make that the goal. They try to hit the ball harder than they can control. They try to hit the ball lower over the net than necessary. They try to hit the ball a little closer to the lines than they are capable of over-and-over again. I know almost nobody who hits a rally ball at a speed that they know they can make 50 or 100 times in a row. Why not? Because to do that you run the risk of being called a pusher. Who want's to be called a pusher?

So if you just put balls in play over and over and over again, if you try for every ball and play within yourself, you'll find that over time you will have very satisfactory tennis results.

If, however, you want to be exceptional, to be among those who are capable of winning matches, then you are in for a long, tough struggle. I'm not saying you shouldn't embark on that journey. Mastering anything is very rewarding. The downsides to failure in the pursuit of tennis mastery are low. Unless you spend your whole life pursuing that dream, to the expense of your family, a job, any life savings, you probably won't regret trying to become exceptional at tennis.

But you will fail a lot along the way. Hitting winning shots is hard enough against a quality opponent during practice. It gets harder during matches and harder still during tournaments. As the stakes go up, the pressure goes up, and the low margin of safety inherent in the winning shots begins to take its toll. Even at the very highest levels of tennis, very often the defensive player will win against the offensive player (see Nadal vs Federer, for example).

So embark on the journey toward greatness if you'd like. But if you want to have satisfactory results, it's easier than you probably realize. Get the damn ball in play. Do that over and over again and see what happens.

Good luck.

### National Federation

In an earlier post I wrote that I don't think big, top-down systems will develop world-class tennis players.  They may work in smaller, homogeneous countries.  There is some evidence that such systems enhance player development in France and Spain, for instance.  I suspect those may be short-term phenomena, but time will tell.  I'm even more skeptical of a top-down, nationwide system in the USA.

The USA has over 300 million people and a tremendous variation among the people, in ethnicity, income, culture, interests, you name it.  The USA is a diverse country.  The most diverse country in the world, I bet.  So what is USTA Player Development to do?  How can they run a system that produces world-class players?  What would such a system look like?

We had a system, or at least a structure of tennis, that produced world-class players in the past.  It was an evolved structure that included country clubs, tennis clubs, public parks, high schools, colleges, and universities.   Tournaments were held in a wide variety of venues, organized by private clubs, schools, cities, and the USTA itself.  The system was diverse, like the country itself.

This structure still exists, but is deemed to be inadequate since the US has failed to dominate the world tennis scene since the retirements of Jimmy Connors, John McEnroe, Jim Courier, Michael Chang, Pete Sampras, and Andre Agassi.  Andy Roddick and James Blake held top-10 world rankings for several years in the 2000s, with Roddick winning the US Open.  Mardy Fish, Sam Querrey, and John Isner have been ranked in the 10-30 range recently.  But that's not good enough, according to the USTA and the American tennis public.  We need to be number one again.  We need to win major tennis tournaments again.  We.  One of us.  An American.

Well, then.  We must do something.  Design another system.  The problem is, we didn't design the first system.  We don't know how to design a system that produces major champions and the number one tennis player in the world.  We never designed the old system.  It evolved.

Might a better system evolve?  How could the USTA enhance the chances of a better structure, or at least enhance the chances of another flowering from our current system?

I think the best way to do that is to continue to sponsor tournaments like they always have.  I think they should scrap large-scale plans and instead fund thousands of small-scale experiments.  Thousands of small-scale experiments would remain faithful to the structure of the country and to the structure of the existing tennis system. One experiment I would like to see is prize money for junior tournaments, say the 16s and 18s.  Allow juniors to play NTRP adult tennis.  Get passionate little kids playing adults as soon as they want to.  Provide seed money for a bunch of sand-filled carpet courts in California and the Southwestern US so kids can learn to slide like they'll need to on clay.  Those are just a few ideas.  We're only limited by our imaginations.

If any of the experiments prove successful, try to scale them up.  Try them in other locations.  See if they generalize.  If not, no big loss.  Spread the money among thousands of competing organizations.

Tennis is an individual game.  Great players share many qualities, of course.  But I'm skeptical of a national system for producing individual greatness in tennis or in anything else.  Especially in the USA.  I'm much more optimistic about diverse, micro-experiments in a diverse country.

## Monday, June 13, 2011

### Altitude: Hypothesis

My contention is that we cannot properly train kids to play low-altitude tennis at high-altitudes.  Training world-class tennis players is a fools pursuit for most of us, obviously, but humor me.  In the USTA's Intermountain Section, most of the tennis is at high altitude, Denver and Salt Lake City.  Las Vegas is at much lower altitude so I'll ignore the success of Andre Agassi in this discussion.

We have produced very, very few top-ranked juniors nationally, and almost no world-class tennis players in the higher altitudes of the US.  Utah had Brad Pearce and Greg Holmes.  Colorado had Jeff Salzenstein.  I'm sure I've missed someone, but that's about it.

Here's a testable hypothesis.  The Intermountain Section (excluding Las Vegas) produces some very highly ranked juniors in the younger age groups, but the longer the kids train at high altitude, the further they fall behind their peers.   It seems reasonable to me that we would see good little kids come along at about the same rate as other areas, but that as the kids grow and the game gets faster, the negative affects of the altitude (ball control, bad reaction habits) begin to exert their influence.  So that by the time we get to the older junior age groups and the college and professional ranks, the ratio of high-altitude players in the higher rankings falls.  In this analysis I exclude kids who spend some years here as kids, but who move to a lower altitude to train later.  I'm interested in kids who spend the vast majority of their time training at altitude.

If I get the time to go back and look at the USTA ranking data over the years, I will report those results here.  I hope that someone beats me to it.  I am quite curious to learn if my hypothesis holds.

### More on Altitude: Balls and Courts Part 2

Paul Lubbers made the two obvious suggestions to help us account for our thinner air.  First he suggested the "green" ball.  That's the 25 - 30% reduced compression ball.  It's actually a combination of lower compression and less mass that makes for a roughly 25 - 30% reduction in speed.  Second he suggested clay courts.  Good suggestions, both.  But both have problems.

First, the ball.  The green ball over-compensates for the thin air at the altitudes where I live (roughly 1600 meters above sea level).  Since this is all about me, and not about people living at 1700 or 1900 meters, that solution doesn't quite cut it.

Second, the clay court option.  As I've written before, we live in a dry climate.  Clay courts are prohibitively expensive for most cities, clubs, etc.  The under-ground hydration systems work well, but they are expensive and any problems are rough since the system is under the courts.

A friend suggested to me that the reason we have only a 9% reduction in compression may (and I stress MAY) be that the ball manufacturers can still pass off the high-altitude ball as a lower-priced option at lower altitudes.  The lowest quality ball sold at discount stores needn't be "approved for tournament play" to sell well.  And those buyers won't notice a 9% difference.  That's only a couple of weeks or months of aging and that's not a big deal to less serious players.  But if the manufacturers were to make a ball that was 17% lower compression, well, that may be a bit too much to ask low-altitude discount shoppers to buy.  I am not an industry insider so I can't say if this is true or not.  But I think it's reasonable.  Ball manufacturers, like all manufacturers, like to have outlets for excess manufacturing.

We may be stuck up here taking the lesser of evils approach.  I believe that training and playing with lower compression balls is the lesser of evils.  Sure, our players will struggle controlling the ball when we go to lower altitude, but at least we'll be prepared to play long points.  The shorter points at low-altitude will be a relief!!

## Sunday, June 12, 2011

### Altitude, the Ball, and Habits

I live at a relatively high elevation, roughly 5,300 feet (1600 meters) above sea level.  The air up here is roughly 16-18% thinner, measured in density or pressure.   In order to compensate for this difference in atmosphere we play with a ball that is roughly 9% lower compression than the standard low-altitude tennis ball.  A lower compression ball will not move as fast as it comes off the racquet.  But our high-altitude ball is the same volume, weighs the same, and has the same nap as the low-altitude ball.  There exist larger balls that are approved for play at altitudes above 4,000 feet, but I haven't seen one of those in many years.

It doesn't seem to me, both thinking about it and from my extensive experience playing at both lower and higher altitudes, that a 9% difference in compression compensates adequately for our differing environment up here (and higher).  Maybe it's not a big deal to tennis federations and ball manufacturers.  How many tennis players live at altitudes above 5,000 feet?  Not many relative to the total tennis market.  So this isn't a huge issue to anyone but us high-altitude tennis players.  But what are the ramifications of learning to play and playing at this altitude with a ball that compensates for roughly half the difference between sea level and our altitude?

I think there are two main problems.  First, we cannot control the ball as well as our counterparts at lower elevations.  We have to impart way more topspin, hit the ball much slower, or hit the ball much lower to get it over the net and into the court.  This affects how kids learn to play the game and how the game is played by adults.  Second, we develop bad reaction habits in two respects.  First, we think that our finishing skills are better than they are so we relax after hitting a shot that, if played at lower altitude, would come back.  That is, our opponent at a lower elevation would get to a marginal ball that our opponent up here cannot get to.  So we think our finishing skills are better than they are.  Second, we give up on, don't chase, a marginal ball that we could have gotten and played at lower altitude.  We learn that certain shots are not within our range, so we don't go for them.  But our range is partially determined by the amount that the air slows down our opponents' shots.  So we learn to not try to get balls that we could get, at the margin, at lower elevations.

These are significant detriments to developing and mastering tennis skills and to playing the game in a way that succeeds at lower elevations.  So what can we do?

We can use an even slower ball and slower courts.  I may have written about this before, but there exist balls that are 25% to 30% slower than regular low-altitude tennis balls.  Penn makes one (called the Control +, I think, with a green dot on it) and so do Wilson, Prince and Tretorn (the Fun Lite).  These balls are both lighter (so the air slows them down more) and lower compression (so the initial velocity is lower) than "regular" balls.  That means they are also much slower than the 9% lower-compression high-altitude balls we play with up here.   These balls over-compensate for the thinner air up here, but in many respects that's better than our current under-compensating balls.

Since our environment (dry) isn't conducive to inexpensive clay courts, most of our courts are fairly quick.  So we have thin air (fast) and hard courts (faster than most clay).  Unless we can get slower courts, perhaps a ball that compensates for both our thin air and our predominantly faster courts would allow us to develop better players in Denver, Salt Lake City, Mexico City, Johannesburg, and Quito.

Those balls exist now.  Why do we continue to use balls that do a half-assed job of simulating the game the rest of the world plays?

UPDATE:  I just attended a USTA Player Development workshop focused on high-performance training.  The workshop was in Denver.  Mile High City.  I asked for help with the effects of the thin air.  "I can't help you," said Paul Lubbers, USTA Coaching Education Director.  Well there you go.  As I said, we're on our own.

## Tuesday, June 07, 2011

### String Lubrication

After reading about the spin-producing benefits of lubricating tennis strings, I thought I'd try it out.  I went to WalMart and bought some WD40.  I strung a Prince EXO3 Tour 100 with 17 gauge Gosen Polylon at 51 lbs.  About an hour later I sprayed the strings and began to play.  I don't know if I was producing more spin than if I had not sprayed since I have no way to measure spin, either before or after.  But I was producing a fair amount of spin.  I also could tell that the strings were springing back nicely.

This spring-back was in contrast to how the same string at the same tension in the same racquet performed for a friend of mine this weekend.  His strings moved and failed to snap back.  Consequently he got only three hours or so from a full bed of polyester string.  My next step will be to spray his racquet and see how it changes the spring-back and durability for him.

During my 90 min hitting session, I chose to reapply the WD40 once near the end.  I had no good reason to do it, other than I had the lubricant with me and thought my opponent would get a kick out of it.  I couldn't really tell much difference before and after the reapplication.

UPDATE:  I have a racquet strung with Luxilon that I've only hit with for a few minutes (15 roughly) that is starting to move and not snap back.  Today I'll spray those strings and see if they spring back better.  Another update later.

UPDATE 2:  Failure regarding the Luxilon Adrenaline 1.25 mm lubricated with WD40.   I hit with it today for about an hour, in addition to roughly an hour two days ago after I strung it.  The strings seemed to spring back better than before.  Unfortunately the strings broke in roughly two hours of hitting.  I had hoped for much better.

UPDATE 3: Silicone spray works better than WD40. It lubricates the strings but doesn't get on the balls or the court, at least not nearly as much as with WD40. I don't know if I get more spin, but the strings do seem to snap back better than without the spray. They may produce more spin and last longer. Or not. But at \$2.29 a can or so at WalMart, I'm gonna keep trying it.

## Monday, June 06, 2011

### Nadal d Federer: Defense beats Offense

I may as well chime in with my comments on the final from Roland Garros yesterday.  Federer definitely played a very good match.  He was hitting his shots the first seven games.  My feeling at the time was that it would be tough for him to sustain that level throughout the match.  That's been everyone's problem in beating Nadal over five sets in Paris.  Soderling did it once.  On that surface over three out of five sets, Rafa's defense is simply too good for anyone's offense.

I thought that Federer did a couple of things tactically that I think helped him beyond just great shot-making.  I liked when he stepped up and drove second-serve returns against Rafa.  Rafa is a great defender who is in his worst defending court position immediately following his second serve.  Rather than defending from 10 feet behind the baseline, Rafa has to defend that shot from very close to the baseline.  That's not easy to do.

I also liked Roger's use of the slice backhand and drop shots as the match wore on.  I thought those drop shots kept Rafa unsure of how deep to play in rally and defending situations.  Roger hit several outright drop shot winners and that threat kept Rafa up a bit closer than he would have liked, allowing Roger to hurt him with backhand drives on occasion.

Roger also took a few more balls out of the air with his forehand.  That's a risky play for sure, but you have to take risks to beat Rafa on clay.  That's why people rarely beat him on clay.  Rafa forces players to play lower margin of safety shots to beat him.

Perhaps I'm a man with a theory looking for confirmation, but I found confirmation of my general theory that at most levels on most surfaces, defense beats offense in tennis.  Roger Federer is the greatest offensive player in tennis history.  His serve and forehand are two of the best weapons in the history of the game, if not the best weapons.  Yet they are not good enough to beat the greatest defender in the history of the game on the clay of Roland Garros.

ADDENDUM:  One more thing.  I was very impressed by Federer's forehand in the first seven games.  It seemed to me, without going back and looking at the tape, that virtually every time Nadal played a ball to Federer's forehand, he lost the point.  Maybe not right away.  But Federer was in utter control once he was able to hit a forehand.  That's tough to sustain, obviously, but I was struck by just how fabulous a weapon Federer's forehand can be when he's in full flight.

## Saturday, June 04, 2011

### Threat Assessment

Rather than asking a coach or a teacher what I should do during a tennis match, my modus operandi was to go down a quick checklist.

1) Can this person put enough balls in play to beat me?  I usually assessed this in the warm up.  As a kid I played tennis in Minnesota and in the early rounds, the answer to this question was often "no".  If the answer was "no" I simply hit balls over the net and waited for the opponent to miss.  If, "yes", on to...

2) Does this person have an obvious weakness?  Again, obvious weaknesses show up in the five minute warm up.  Usually this will be a backhand.  Forehand weaknesses are usually more subtle.  Volley and overhead weakness, movement trouble, short second serves, etc are often pretty obvious.   If I found a weakness, I exploited it.  If I couldn't find a weakness, I'd move on to ...

3) Can I find a weakness?  This is tougher than spotting an obvious weakness.  To do this you have to move the ball around more during play.  You have to mix up velocities and spins.  Perhaps the backhand is sound, but not so sound on the run or high or low.  Modern forehands often break down under pressure or when the player is on the run to their dominant side.  Usually what I'll do is just move the person around the court and observe the shots I receive in reply.  If I can't find any weaknesses...

4) I'll begin to try different game plans to see if I can win points.  In my case that was generally to serve and volley.  Hitting winning shots is easier to do from the front of the court than from the rear of the court.  If you're a good defender, maybe you draw your opponent forward so you can pass or lob them.  Maybe you just grind them down, forcing them to beat you with winning shots from bad court positions.

In the course of going down this checklist, hopefully I found some way to win the match.   Finding a weakness and being able to exploit it to win a match are two different things.  It may be that your opponent can't do something as well as something else, but you can't get to the weakness, or worse, the weakness is still better than your strength.

There is no magic bullet for every opponent.  But going down some sort of checklist will help you find ways to win more matches.

## Monday, May 23, 2011

### Player Development Systems

I ended my last post with a comment that the changing tennis landscape has implications for the USTA's Player Development Program.  Any system that's purpose is to produce world-class tennis players is a system that takes time.  Ten years at a minimum.  The kids get into the system at a young age and by the age of 18-28 one or two or more of them dominate the international tennis scene.  That's the goal anyway.

So you're in charge of such a system, nationwide.  What do you do?  Well Patrick McEnroe is that person in the US and he has hired Jose Higueras as his head coach.  Together they map out the training of young tennis players.   Both men agree that young American players are hurt by not playing enough on clay.  With an eye toward the success of Spanish and French players, and of Federer and Djokovic, all of whom played predominantly on clay as kids, McEnroe and Higueras are making the top US juniors train more on clay. They have installed clay courts at their regional training centers and at the National Tennis Center in New York.  Training on clay has worked for the current generation of stars, so we'll have to train our next generation of players on clay if we want them to be stars.

That's the argument.

Notice any problem with that line of reasoning?  Ever heard of a general fighting the last war?

If the landscape does not change over the next ten or twenty years, then starting our young players off on clay is a good call.  But what if it does change?  What if the game speeds up again for some reason?  Increased skill or different technique or another type of string.  What if the courts or balls of ten or twenty years from now are much faster or much softer or much harder or something that doesn't suit players who grew up playing on clay?

Any long term plans are subject to this type of risk.  Ask any business person or government planner.  The best laid plans of mice and men...

The longer the plan, the longer the process, the greater risk that the plan will not work out as you hoped.

So what's a national tennis federation to do?  Ah, another post!

## Sunday, May 22, 2011

### As California Goes

As California tennis goes, so goes American tennis.  Simplification?  Sure.  But California is our most populous state and a state with a long and rich tennis history.  It's reasonable to expect great American tennis players to come from California.  They have in the past.

California tennis is played on hard courts.  Players generally hit the ball fairly flat and take the ball on the rise.  They hug the baseline and play a forcing style of play.  That's what Tom Stow taught in Northern California and I think Robert Landsdorp favors that style in Southern California, too.  I don't think that's an unfair or misleading characterization of California tennis.

So how does that style of play work at the top levels of tennis in 2011?  I think not well.

Two primary changes in the tennis environment have worked against the California style.  The first is the strings.  The new co-polyester strings allow for much greater spin generation.  This allows players to hit with higher ball speeds and get the ball over the net and into the court.  The second change is to the court surfaces.  The hard courts are far slower than in the past and even Wimbledon's grass courts favor baseline players.

Playing up near the baseline, taking the ball on the rise, and attacking behind those sorts of groundstrokes is very difficult now.  Players who grew up on clay, playing well behind the baseline, have time to get to the ball and rip shots with their co-poly strings.  The neutral balls from these types of players even give the California-style player a lot of trouble.  A ball hit fairly high over the net with a lot of speed and spin is extremely difficult to hit on the rise, with authority, and adequate margin of safety to keep errors low enough to win.

Unless California tennis changes to reflect the new conditions under which top-level tennis is played, I don't think we can expect many great players to come from California.  That dramatically reduces the chance of there being any great American players in the near future.

If the conditions on tour change maybe the California-style will re-emerge as dominant.  If not, the players and coaches in California will have to change or be selected against by the very competitive tennis environment.

UPDATE:  This is awesome.  As soon as you write something it can become obsolete.  I turned on the French Open a few minutes ago to watch Ferrer and Nieminen play.  Brad Gilbert says that he's seeing more and more hard court tennis being played on clay this year.  The balls on tour are quicker than the last few years and the clay courts are playing much quicker.  So players, like Djokovic and Ferrer, are moving up onto the baseline much more consistently.  Gilbert says that he's seeing a lot more "one two" tennis, meaning serve and forehands ending points.

I saw one point where Nieminen hit a second serve and Ferrer ripped a return from inside the baseline.  Nieminen got the ball back, but weekly and Ferrer unloaded on another forehand from inside the court.  This time Nieminen barely got the ball back and Ferrer finished him off with a high forehand winner from about the service line.  One, two, three.  Receiving.  On the clay of Roland Garros.

Can the return of the dominant Californian be far behind?

The landscape can change quickly.  What does that mean for the USTA Player Development system?  The subject of another post...

## Monday, May 16, 2011

OK, I've been pretty harsh on the value of coaches and coaching lately on this blog.  It's only fair that I toss up an example of where coaching helped.  In this example, I think nearly all the credit should go to the player.  I've given this sort of advice to countless players without any effect.  Same message.  Same messenger.  Different recipient.  I say the recipient matters more than the messenger and the message.  In any case, some coaching did help.

Below is an image of a player at a critical moment in his service motion.  He is just about to lose contact with the ground.

You can see that at his final push off the ground the force vector from his foot through his mass center angles toward the back fence.  Not good.

I took a video (from which the drawing was made) and showed him his serve.  I told him to let his weight flow forward more as he was pushing against the ground.  Here is a similar picture of his very next serve:
With one video and one sentence of instruction, this player improved his service motion dramatically.

Let's insert the before and after videos.  Before:
And here is the better (after) video:

Look at how much better his weight flows into his serve on the second video.   Look at both his hip motion as he pushes off and where his left foot lands relative to where it started (the baseline is a nice reference).

As I said, the lion's share of the credit goes to the student.  He is a great athlete who possesses more body awareness than most people.  But I have to admit that this little bit of coaching helped improve his service motion.

Total elapsed time of the lesson?  Between one and two minutes.