Why It's Almost Impossible to Hit a 160 MPH Tennis Serve | WIRED

It's one of the most exciting moments in any tennis match. A player steps up to the baseline, maybe bounces the ball a few times, and then smashes an ace past their opponent. And while the pros make it look easy, the tennis serve is actually an incredibly complex stroke. Hitting a tennis serve effectively is one of the hardest things in sports to do. Even if you somehow master the mechanics, there's also strategy to consider, like whether it's your first or second serve, where your opponent is standing, and what your last serve was like. Just like in baseball, where pitchers want to avoid throwing the same pitch over and over, servers like to mix things up, keeping their opponents on their toes. One thing that most serves have in common, at least at the professional level, is speed. Lots of speed. We're talking about serves that leave the racket at 120, 130, even 140 miles per hour. And the absolute fastest serves on record reach into the 150s. But is that as fast as we can go? Today, we're going to look at why serving a tennis ball 160 miles per hour is almost impossible. To find out what it takes, I talked to one of the biggest servers in the game. Mechanics are critical. Having good mechanics, having good flexibility, allows you to kind of have that leverage to make the ball really move. Tested my form with a sports scientist. We don't want to be going straight up. We actually want to be going in that direction there. Found myself on the receiving end of some pretty humbling serves. And even sacrificed a camera. Look at this. That is what 120 some odd mile per hour serve will do to your GoPro. The game of tennis has always had huge hitters. In 1974, at a speed competition held at the U.S. Open, Australian Colin Dibley was clocked crushing a tennis ball at 148 miles per hour. But that was at a competition designed specifically for testing speed. In match play, most players don't hit as hard as they can because they also have to control where the ball goes. Still, serve speeds have increased over the years. Through the 80s and 90s, the fastest serves on record were in the 130s. In the late 90s, we saw the first serves in the 140s. And in the early 2000s, we saw them creep into the 150s for the first time. The fastest serve ever recorded? That came in 2012, when Australian Sam Groff was clocked serving a tennis ball at 163.7 miles per hour. Now, the Association of Tennis Professionals does not recognize that serve. And that's because Groff delivered it at what's called a challenger event, where the serve speed guns aren't subject to the same standards as those on official tour events. The fastest serve recognized by the ATP? That was delivered by American John Isner. So what does it take to hit a serve that fast? And what's keeping them from getting faster? You want to jump a little towards where you're serving. That way, the momentum of your body is kind of helping you out with the power and all that. Ulysses Blanche is a 21-year-old pro who can hit serves up to a blistering 138 miles per hour. We visited him at the USTA National Campus outside of Orlando to learn some fundamentals. So what's the first thing people learn when they learn to serve? Throwing the ball up. Tossing it and getting that consistent? Yeah, trying to get that as consistent as possible. Yeah, let's see if we can at least clear the net this time. Get a little higher if you can. As you can see, my form was terrible. But with Blanche's help, I was at least able to improve my serve speed. 77! But it didn't take long for that pride to wear off. So now Ulysses is going to try. Remember, 77 miles per hour is the speed to beat. I'll keep that in mind. I'll try to do it. He's casually hitting triple digits in his warm-up. And if you think hitting the ball that fast is tough, just try returning it. Look at it this way. For a 130-mile-per-hour serve, you've only got about half a second to react. For a split second, every single time he serves, I'm just like, no, I got it. It's going here, and then I don't have it at all. OK, so I definitely won't be joining the ATP anytime soon. But I'd at least like to understand why my serve is so much slower than Blanche's. So what do you think is keeping me from serving faster than 77? I mean, it's technique. All that is technique. So here you are over on the left. And then this is Ulysses' serve on the right. We recorded our session with cameras from multiple angles and then asked USTA performance analyst Dave Ramos to compare our mechanics. Quite a bit of difference from one to the other, right? The biggest difference is how we store and release energy. It all starts in our legs. Blanche's are straight, but mine are bent. That's because I'm using my lower body to help throw the ball into the air. That's very common, actually, for new servers, to almost feel like they have to put some energy into the toss. Ramos says your arm is more than strong enough to lob the ball on its own. And involving your legs at this stage actually just adds more complexity to your movement, which can make your ball toss less consistent. Now, look at our hitting arms. Blanche activates his by drawing it back in one fluid motion. My arm? It barely moves. At the point of release, our bodies could not look more different. Look how open Blanche's chest is. By rotating his hips and his shoulders, he's already begun storing energy in his upper body. This is called coiling, and I am really, really bad at it. Just watch what happens in the next stage of the serve. By the time the ball reaches its apex, Blanche's upper body is so tightly coiled, his shoulders are pointing at the sky. Mine are practically level with the ground. You'll also notice that while we've both bent our knees to store energy in our legs, Blanche has shifted his weight in a way that will allow him to leap not just up but forward towards the ball as he explodes out of his squat. This allows him to transfer the power that he stored in his leg upward, through his body and into his racket by uncoiling his hips, his torso, and finally his shoulders. Right before impact, Blanche's arm is fully cocked and the head of his racket is pointing right at the ground, the result of a huge external rotation in his right shoulder. Just look how high his elbow is relative to his hand. My external rotation, by comparison, is basically non-existent, which brings us to the point of contact. You're basically looking for as close to a straight line from the tip of the racket, down through the hand, to the elbow, to the shoulder, and then to the hips, and then out through the body. So it looks pretty much like a straight line, where you can see on yours you have a couple of segments. We've got all kinds of angles going on. The good thing is you are centering the ball, which is pretty good, but the tip of the racket comes down to the hand, then the hand goes down to the shoulder, and then the rest of the body is one sort of straight line. Those zigzaggy lines highlight breaks in my kinetic chain, the sequence of rotations that sum the forces generated by my lower and upper body. Okay, go ahead. The kinetic chain is crucial for a high-powered serve. A very efficient kinetic chain energy transfer means that whatever energy you can create from your ground reaction forces, nearly 100% of that gets shifted up through the body, out into the ball. That's Mark Kovacs, a sports scientist who works with some of the hardest hitters in the world. We visited his lab outside of Atlanta, Georgia, where he covered me in sensors and had me serve on a pressure mat so we could pick apart my serve. One of the first things we noticed was my lack of force production. Even if my technique had been perfect, I just wasn't generating that much force with my legs. Your peak force here is between 800 and 900 newtons, which is pretty normal for a recreational-type player. The pros are 50% more than that, many of them, up at 1500, some of them even a bit higher than that. Plus, not only was I generating less force, I was also putting that force in the wrong place. So you can see, it looks like a vertical jump right there. So if we look at it on the screen, that would be a standard-looking vertical jump if I was doing an NBA combine or NFL combine. I'm actually reasonably happy with the position there. But on a tennis serve, we don't want to be going straight up. We actually want to be going in that direction there. And finally, I wasn't rotating my shoulders enough. Remember, it's all about that coil. So you've got what we call an inefficient kinematic sequence. You know, it's all happening at once, so you're not getting that benefit or that summation of forces that we'd like to see. An inefficient kinetic chain transfer means that that 100% of ground reaction force that you've produced, you may only get 70% or 60% of that into the ball. That's a very inefficient model, and that also potentially increases your injury risk because you have to do more in the upper body. As you can see, you also collapse right at the end, which doesn't look very healthy there. We're bent over. We're collapsing, falling to the side. I'm just keeping track of the adjectives Mark has used to describe my form. We've got weak, inefficient, and collapsing. Again, they're all fixable. That's the good thing. There's plenty of opportunity for improvement here, and that's what we like to see. One thing I can't fix, my height. For a tennis player, you're not that tall, so the net's a little higher for you, so you can't really hit down on it. And that makes a difference. Riley Opelka is one of the fastest servers on the tour. He's also tied for the tallest. You know, being seven foot helps. The main difference is the trajectory, and the way the angle it's coming at is significantly higher, so the way the ball bounces off the court, the peak height of it is foreign to a lot of players. They're not used to seeing a seven footer serving from that height, and the ball coming from that angle. You've got to really look at some of those tall players if you're looking at the absolute fastest servers, the John Isners of the world, Riley Opelkas. They're all six, seven, and above. You can actually graph that correlation. Here's a chart of some of the fastest serves on record in relation to player height. That line visualizes the relationship between player height and speed. You don't need to be tall to hit hard, but it definitely helps in a couple concrete ways. You've got longer levers, so you can store energy over a greater amount of time, and it allows you to cement your forces over a greater distance. The second big thing is you've got a height advantage from a geometry standpoint. Six foot seven is what the estimated height is for people that can actually hit down on a serve. Anyone under about six foot seven actually is still hitting up on the serve. So if you're hitting up on the serve, you're fighting gravity. If you're hitting down on the serve, gravity is actually helping you. But height isn't everything. Part of developing a big serve is having good coaching, good mechanics. We've always been on top of my flexibility through my shoulder, through my spine, good mobility. It's all critical. There are a lot of players that are mid six feet that have very, very fast serves. Andy Roddick was an example. Six two-ish range, and still has one of the fastest serves of all time. So it's not a one-to-one correlation, but it is that predictor. It's one of those predictors that the taller you are, the higher the ceiling you have to have a great and fast serve. If you have someone with pure technique, nearly a perfect technique, which Andy Roddick does have, and you add height to it and the technique is maintained, then for sure you're just going to increase serve speed from that standpoint. So that's where the argument can be made that we do have still a higher ceiling for serve speed potentially. So what drove those steady increases in serve speeds in the 80s, 90s, and early 2000s? And why aren't we seeing them today? A lot of it has to do with technology sort of being relatively consistent over the last five years. If there is a technology change going forward, we could see a spike. Over the decades, it's the evolution of the racket that has probably had the single biggest impact on serve speed. For much of the 20th century, wooden rackets dominated the game of tennis. But in the mid-70s, manufacturers began experimenting with materials like carbon fiber and resin to produce rackets with much bigger heads. In the 1970s, your standard wooden racket had a surface area of about 70 square inches. But the modern racket is well over 100. And that increase in size had two effects. Number one, it made the sweet spot bigger, which made the game a lot more approachable for amateurs. Typically, the sweet spot is in the upper part of this racket, and it's maybe a little bit bigger than the size of a ball. And in modern rackets, it's quite a bit bigger. But on a racket like this, if you don't hit the racket dead center in the middle of the strings, it's not going to respond or it's going to be unstable. But professionals didn't really need a larger sweet spot. And for them, bigger rackets had a different effect, the ability to put more topspin on the ball. That's because more surface area means more room for the ball to roll across the racket and gather spin. Thanks to a phenomenon known as the Magnus effect, a ball hit with more spin dives towards the court at a sharper angle once it clears the net. Putting more spin on the ball allowed pros to lower their risk of hitting out of bounds when they hit harder. The result, more powerful play and faster serves, especially for bigger, stronger players. Advances in string technology have also had an impact on serve speed. Where players used to string rackets with cow gut, today's pros use some combination of polyester strings that can be made fat or thin or round or square-shaped and strung at a variety of tensions depending on a player's needs and style of play. It's important to have just the right tension because it gives you the ability to create power without a lot of effort. So if you string higher, you're going to have more control. If you string lower, you have more power. In fact, a lot of players have several rackets to choose from in a given match. They'll use one for serving, one for returning, and a whole bunch of backup rackets for anything that comes up. I was sitting with a coach who was preparing Serena Williams rackets. She uses 11 rackets in a match because she has all the bases covered. Players are incredibly sensitive to racket tension and conditions and a lot of times it happens, it changes as the match goes on, right? If it gets more humid or if it rains or the balls change a little bit, they want to have a lot of options. The ball can affect serve speed too. New balls tend to fly faster than old ones. That's because balls lose pressure over time and the more you play with it, the fluffier it gets, which increases drag. Environmental factors can also impact your serve speed, including whether you're playing on a hard clay or grass court. Court surface can play a bit of a role even though it's being measured in ball speed and through the air. What court speed does is it changes your strategy. If you've got a really slow court, you may not try to serve as hard. You may be more strategic so it changes how people serve. And then there's air density, which is affected by things like altitude. The higher elevation you're at and the more hot and humid the air, the less resistance the ball experiences translating to faster speeds. Conditions are everything. I guarantee you, you won't see a guy come to the French Open on a slow clay court in Europe when it tends to be a little cooler out, maybe rainy. You won't see a guy serve over 150 there, but if we do see a serve, you know, peak over 160, I would think it happened somewhere on a hot, fast, hard court, somewhere like in Atlanta or Washington, D.C. So what have we learned? Number one, if and when someone finally does break into the 160s, officially, they will almost definitely be incredibly flexible in their hips, torso, and shoulders and be able to uncoil those elements in the precise way necessary to translate power from their legs, through their body, and into their racket. They'll probably be swinging a cutting edge racket and hitting a brand new ball. And odds are pretty decent that they'll be playing on a hard court in hot, humid weather. And they'll probably be tall. The point is, no one can say for sure when all of these variables from form and fitness to height and equipment will align or whether they will at all. But until they do, keep in mind that what the hardest hitters in the world are doing today is already almost impossible.