Why are Men’s Tennis Champions Getting Older? (and the physics of topspin)

Why are Men’s Tennis Champions Getting Older?
(and the physics of topspin)

The remarkable play of Roger Federer at age 37 has not been seen before by the current generation of fans.  After not winning a slam for five years, he suddenly resurrected his career and has rolled to three slam titles in the last two years.  At the same time, Rafael Nadal, now nearly 33, also added three more slam titles to his career haul.

Just a few years ago, this sort of longevity seemed impossible.  The likes of Borg, McEnroe, Wilander, and Edberg—who all had multi-slam winning, yearend-#1-ranking careers—won their last slams by age 24 to 26.  When top stars like Lendl (29), Connors (31), Sampras (31), and Agassi (32), won their last slam titles, it seemed these were their last gasps before doddering into retirement.  By the time Sampras retired it was assumed that a good career could be had by age 25, and the later 20’s were a period of decline, with only decrepitude possible in the 30’s.

Meanwhile, our current world #1, Novak Djokovic, winner of the last three consecutive slam meetings, turns 32 in a few days.  He very much seems in his prime with many years to go – he’s quick, he’s fit, and his major rivals, Federer and Nadal, are beating everyone else and have paved the pathway of belief that good tennis can still be played in the late 30’s.  For the top players of all eras, peak age for slam winners has been ages 22-25.

But as of now in 2019, there are no former slam champions younger than age 30.  Both Marin Cilic and Juan Martin Del Potro will turn 31 in September.  Surprisingly, no man born after the 1980’s has lifted a slam singles trophy.  This is completely unprecedented.

The first player born in the 1980’s to claim a slam was Marat Safin taking the US Open in 2000, 20 years after the 80’s began.  The earliest slam won by a player born in the 1970’s was Michael Chang’s 1989 French Open, 19 years after the 1970’s began.  In fact, looking back through history the current 29 year wait (and counting) for a player born in the 1990’s to claim a slam title is unique.  The previous longest wait was 24 years, for a player from the 1950’s, with the average for the last ten decades at 21.8 years.

Birth decade	Years to first slam winner	Winner
1990’s	??
1980’s	20	Safin
1970’s	19	Chang
1960’s	22	Wilander
1950’s	24	Connors
1940’s	23	McKinley
1930’s	23	Rosewall
1920’s	22	Schroeder
1910’s	21	SWood
1900’s	22	Cochet
1890’s	22	McLoughlin

Not only are the 1990’s cohort not winning, they are not even getting to slam finals – or at least only rarely.  So far there are only two 90’s-born players that have even contested a slam final, Milos Raonic, born 1990, and Dominic Thiem, born 1993. 

So why are no players from the 1990’s winning slams?  Is the 1980’s generation of champions too good?  Is the talk of the three greatest players of all time—Federer, Nadal, and Djokovic—playing at the same time actually true?  Or is it that the 90’s generation is actually subpar?  Or is it some combination of the two?  There may be some merit to those ideas, but I believe the longevity of today’s players may have another answer as well.

I’ve been wondering if the rapid changes to equipment technology in the 1970’s and 1980’s could have distorted our perspective.  Could the sudden evolution of playing style in the 1980’s have shortened careers, as younger players, who had adapted and grooved better to the new technology, over-powered their slightly older rivals?

Until the early 1970’s, champions in their late 30’s were not unheard of.  Former world #1 Pancho Gonzales was still in the world’s top ten in 1969 at age 41.  Rod Laver was ranked #4 in 1974 at age 36, and Ken Rosewall won his final slam titles at ages 36 and 37.  He also made both the Wimbledon and US Open finals at age 39 in 1974.

And this sort of longevity was not new.  Before them, Jack Kramer in the 1950’s, Don Budge and Fred Perry in the 1940’s, Bill Tilden in the 1920’s and 30’s, and Norman Brookes in 1910’s were claiming the sport’s top prizes well into their 30’s and beyond. 

What was new in the 1980’s was the shortened time in the winners’ circle for the top players.  McEnroe, Borg, Vilas, Connors, Lendl, and Wilander were all playing well into their early and even late 30’s (even Borg was trying and failing at comebacks).  But they were no longer claiming the top prizes the way their many fore-runners had, or the way Federer, Nadal, and Djokovic are now.  Is that just a coincidence?  Or were they getting squeezed out by kids with the new tech?

Changes to racket technology were very slow until the 1970’s.  There had been some minor experimenting with metal rackets or other materials, but the advantages of these alternatives were not apparent.  For the 100 years of tennis history until the 1970’s, rackets were almost exclusively made of wood.

When players from the 1920’s and 30’s talked about whether players from the 1960’s and 70’s were as good as their own generation, they could actually consider how Bill Tilden from the 1920’s would match up against Rod Laver from the 1960’s, if they were both in their primes playing with their own rackets.  Now that sort of comparison is ridiculous.  We know that peak Federer would have killed peak Laver – and that is largely because Federer, playing with his racket and strings and shoes, would have a huge technological advantage over Laver. 

We can no longer accurately guess how a present-day player would match up against a past one because the games they played are so different.  Pulling out old videos and measuring ball speed or spin rate on the ball would reveal the disparity because current equipment allows so much more of both than old wooden rackets did.

Wooden rackets were much more flexible than modern ones.  That flexibility, or wobble, made it more difficult to control the precise direction of the ball.  Making the racket as stiff as possible to provide the players control was always the goal.  But wood, even laminated wood layers, had limitations. 

Wood was reasonably light and reasonably strong.  But it was not as strong as today’s graphite and composite frames.  That lack of strength meant that the racket head could not be too large or the strings too tight.  In order to control the ball and prevent trampolining, the strings needed to be somewhat tight.  But if the strings were too tight they could break the frame.  The larger the racket head, the tighter the strings had to be to prevent trampolining.  But making a frame larger made it weaker and meant it couldn’t be strung as tightly.  So an optimum size of about 65 square inches was reached.  This allowed a 9 inch (23 cm) wide head that was still small enough to allow tight enough strings to provide reasonable control of the ball.

Another great way to control the ball is with topspin.  Topspin allows a player to hit the ball with greater speed or greater net clearance (or both) and still have it drop in the court.  Its advantages were quickly grasped by tennis players.  Herbert Lawford, who played in the second ever Wimbledon championship (1878) became famous for his powerful topspin forehand that became known as the “Lawford stroke.”  He predicted it would make the net game obsolete, however racket technology of the day kept the struggle between baseliner and net-rusher relevant for at least a hundred more years.

Hitting topspin requires brushing upwards with the strings on the back of the ball while striking the ball in the forward direction.  The upward motion of the racket tends to direct the ball upwards and, if the racket face is perpendicular to the court surface, results in a ball trajectory that is both forward and upwards.  This means a ball struck with force will tend to sail long, even with topspin to bring it down.

To counteract this, the racket face is angled forward at the point of contact.  Then the upward momentum produced by lifting the racket to provide topspin is counteracted by the down-angled face of the racket.  In this way, greater force can be applied to the ball and still have it land in, because its trajectory is lower.

For a given topspin rate (upward motion of the racket at point of contact), increasing power requires a greater downward angle of the racket face (angle of attack) to keep the ball in the court.  The more powerful the stroke, the lower must be its trajectory over the net to have the ball still land in.  Increasing the topspin allows the ball to travel higher over the net or allows more speed (or some combination of the two) and still have the ball land in.

So the greater the angle of attack (downward angle) of the racket face, the greater can be the topspin and therefore the speed at which the ball can be struck.  Additionally, since humans are not absolutely precise in hitting the ball exactly the same way each time, greater topspin allows greater margin for error.  If a player can aim a powerful ball to clear the net by two feet (60 cm) on each stroke and still have it land in, that player is much less likely to hit a ball into the net than a player who hits without topspin but must aim to clear the net by only eight inches (20 cm) to maintain the same power.

The angle of attack of the racket face turned out to be a key technological limiting factor in generating topspin.  The upward motion required to generate topspin means that the ball slides further across the string bed during contact.  The greater the topspin, the greater is the width of string bed required during contact.  Using a greater width of string bed makes a player more likely to have the ball hit the frame (and lose control of the ball).  Additionally, increasing the downward angle of the racket face means that the effective height of the frontal plane of the string bed becomes narrower.  Hitting onto a narrower frontal plane (effective string bed) requires more precision and is more likely to produce errors from hitting the frame.  This is why hitting with topspin is difficult.

(courtesy of link below)

It’s complicated, but there’s a decent explanation here.  The impact of all this is that having a wider string bed allows a greater angle of attack, and therefore more topspin, more power, and more control over the ball.  This is why development of the oversize racket in the 1970’s so totally revolutionized the game.

But the oversize racket was not possible with only wood, because wood was too flexible.  A big wooden racket was too bendy to have proper directional control.  And the frame was too weak to string tightly, so the result was a trampolining noodle.

When metal rackets, and later graphite, came to be used, the game started to change.  At first the increase in stiffness from metal allowed greater control, with marginal increases in topspin.  When Borg began using a wood core racket with an outer layer of graphite, the increased strength of the frame allowed him to string it up to 80+ pounds tension.  This board-like stiffness gave him greater control of the ball’s trajectory and allowed him to use more topspin, even without an increase to the frame’s head size.

The game changer was the metal, and later graphite, oversize racket.  The greater width of the string bed meant players could increase the angle of attack of their racket faces to the ball without shanking, and start to add more and more topspin to their swings.  More topspin meant more power and more control.  Development of the widebody frame in the late 1980’s was the clincher.  It allowed ultra-stiff frames that were light and strong enough to handle high string tensions that allowed for control and massive topspin.  Further, the frames became so stiff that even large frames didn’t require extreme string tensions to prevent trampolining.

With the physical limitations to racket size overcome by technology, tennis governing bodies realized they had to legislate maximum frame sizes.  With frames unable to become much stiffer, and string beds limited in their width by the new rules, the amount of topspin that rackets can generate has reached an approximate ceiling.  There have been minor gains through string technology, making grippier strings.  But string gains have mostly been to durability.  A few pro players still use gut strings, an ancient technology, which demonstrates that increases to grippiness from synthetic strings have been minimal.

Racket technology has been relatively stable for about 30 years now.  There have been other gains along the way, like shoes, nutrition, physical training, and psychology.  But their impact is more gradual and smaller in scope than that caused by graphite and the resulting oversize frame in the 1970’s and 80’s. 

Of course it took players a few years to adjust to all the change.  They had to learn how precise they could now be from the back of the court – to realize that they could hit with lots of topspin and lots of power and still pass net-rushers with good margin for error, to work out the new angles available to them. 

It’s interesting that the generation of top players with short slam-winning careers happened exactly at the time that racket technology was changing the game so dramatically.  It’s not that there weren’t players with short careers at the top in other eras, but it’s particularly noticeable that there were no top players winning the biggest titles into their mid and late 30’s at this time of technological change.

Now, with racket technology relatively stable, we are witnessing the re-emergence of long careers at the top of the game.  Is it just coincidence?  The anomaly turns out to be not that players’ careers at the top are long now, it’s that they were short from the mid 1970’s to about 2000.

I think stability in racket size and technology has re-introduced long slam-winning careers. What it doesn’t explain is why no players from the 1990’s have yet won a slam.  Surely the 90’s players would benefit from the new technology at least as much as the 80’s players? For that answer I think we need to look to the GOAT trinity of Federer, Nadal, and Djokovic.  They have effectively suppressed the younger generation by their greatness.

I’ve actually begun to wonder if the 1990’s cohort will ever win a slam.  The most eligible bachelors are likely Thiem, Zverev, Raonic, Tsitsipas, and maybe Medvedev, Shapovalov, and Khachanov.  Or perhaps the 90’s will be by-passed completely and Felix Auger-Aliassime, born 2000, will be our next new slam winner.