Blog # 3 - What’s In Your Racquet?

So how much do you know about your racquet?

Is it your partner forever that never lets you down, or is it your fickle mistress? Does it do everything you want it to or is it just a placeholder until you find your true love? Actually, how much do you really know about your faithful friend?

This episode is meant to be a deep dive into what makes a racquet work for you, and possibly why it doesn’t. To help get us started let’s look at what makes it unique.

Is it a club, or a feather?

It can be heavy, light, or anything in between.  On top of that the weight of a racquet can be distributed along its length in many different ways.  These two statements are the foundation beneath three commonly published racquet specifications - weight, balance, and swingweight.

        Weight - Due to the international nature of tennis, static weight (“mass” from physics class) is mostly referred to in grams. Adult racquets typically range between 275 and about 340 grams fully strung and accessorized. This number is what should register when you put it on a scale. It starts to define our relationship - it can be too light, too heavy, or something in between. Note that the most common weight printed on racquets is the frame without strings. A normal bed of strings will be around 18 grams.

        Balance - The most common length for an adult tennis racquet is 27 inches (686 mm). If you place it on a fine edge looking to find where both ends were evenly balanced that would be  somewhere around the physical middle. Some have more weight out by the strings - termed “head heavy”, while others have more weight at the handle end - “head light”. Where the bulk of the mass resides contributes to how the racquet feels in the hand. Lighter racquets tend to be more head heavy so they don’t get pushed around too much by the ball. Heavier racquets tend more towards head light so they aren’t too hard to swing.

        Swingweight - The most complex of these three specifications is a little harder to explain. Swingweight is a measure of how hard the racquet is to swing. Having a larger number means it takes more force to move it at a given speed but like many things in tennis there are pros and cons. If it takes more work to get the racquet moving, that energy translates into greater momentum, resulting in a faster ball speed when you hit with it.

Just like Goldilocks, you play best when these three parameters are “just right”. A way to think about it is to compare your racquet to a hammer. If the hammer head is too heavy you can’t swing it with one hand. We would describe it as over-the-top head heavy - its balance point would be far from the middle of its length. Because of its high swingweight, if we could hit the tennis ball squarely in the centre with the hammer head it would fly off at a pretty high rate of speed. Unfortunately finishing a point with a finesse volley at the net would be close to impossible. So would your chance of ripping a high RPM topspin shot with that low to high swing path. For that we need strings, what some marketing calls “the engine of your racquet”.

Aren’t all strings the same?

The short answer on many levels is no. They all have the same job - stop the ball, absorb its energy, and return that energy to fling it back in the opposite direction. How that works in a racquet can vary depending on a few factors. The size of the hoop, the density of the weave, the string tension, and finally, the type of string all come into play.

The size of the hoop, or “headsize”.

The head size of a modern racquet can legally be huge, in excess of 130 square inches of space to be filled with strings and today’s technology means it can still be very light and maneuverable. At the other end of the spectrum, modern production racquets aren’t typically less than 95 square inches. This means the spacing of the strings using a common pattern of 16 mains by 19 crosses creates quite a different surface to greet the ball depending on head size. Also very significant is the fact that longer string lengths from edge to edge on a large head have more material to stretch on impact.

This makes your mini trampoline feel and respond differently if the head size is smaller than if it is larger. The smaller tend to feature more of a connection to the ball - a more controlled feeling. The downside is it requires more skill and consistency to reliably connect the centre of the strings to the ball, therefore catching and releasing the ball’s energy in an efficient way.

On the flip side a larger head size makes it easier to find the ball with the strings and the time the two parts stay connected is longer. Since the racquet is generally moving in some direction, the longer the “dwell time”, the less predictable the ball’s direction will be. Although the bigger surface area makes it harder to miss the ball, the added length of the strings can have a mushy feel unless you increase the tension to compensate.

The density of the weave.

Also playing a role is the density of the string weave, which gives you a ratio of more or less string to the spaces between. The number of main to cross strings can vary with any head size.  It creates a different feel much like head size when the racquet design features a closed pattern - more strings, rather than an open pattern - fewer strings. When the ball contacts fewer strings because of open spacing, the energy tends to stretch them more for any given impact. When the pattern is more dense it tends to act as a firmer surface to meet the ball.

The String Tension

Another way to affect the impact with the ball is by varying the tension the string is pulled to during the stringing process. Like both a denser pattern and a smaller head size, increasing the tension the individual strings are pulled during stringing will reduce the time the ball spends on the strings during impact. The feel this creates is generally one of more control but less power. Stringing at a lower tension typically yields the opposite result.

Recommended tensions for modern racquets seem to be trending lower as newer string types are engineered to grip the ball, stretch, and then snap back in the hope of generating more spin. Where tensions like 60 pounds used to be common for recreational players the trend is now more towards the low 50s or below.

The Type of String

There are a large number of different strings available but the most useful way to think of them is by their stiffness. A weave using a stiffer string type will yield a firmer hitting surface much like a smaller head size, a more closed pattern, or a higher string tension. The result of that should be a feeling of more control but less power. Modern polyester strings are the usual choice for these characteristics. For a softer feel with more power the strings are often made of nylon and commonly built from multiple or even large numbers of fibres. These are usually labelled as synthetic gut or a multifilament string.

The Thickness of the String

Just like rest of the string characteristics we’ve just covered, the thickness of the string will also affect the interaction between the ball and the racquet. In North America strings commonly use American Wire Gauge (AWG) measurements, where the larger the number, the thinner the string. Most players will be using 17 gauge (approx.1.23 mm) or 16 gauge (approx. 1.30 mm). If the player wants more “bite” on the ball they may go down to an 18 gauge but the tradeoff will be less durability. If the player frequently breaks strings, they could choose a thicker 15 gauge but that may come at the expense of grip on the ball and “feel”.

How Stiff is Your Racquet

Going back to racquet frame, another feature making your racquet unique is its stiffness. By varying the amount, the racquet will flex, and even where on its length the flex happens, the designer can dictate a number of performance characteristics. When the ball impacts the strings there can be surprising physical forces involved.

When you watch ultra slow-motion video of the racquet to ball impact you will see an odd mixture of the strings stretching, the ball deforming, the racquet head being driven backwards, and the whole frame flexing and wobbling. This is usually accompanied by a stretching of the muscles in the player’s hand, wrist and forearm but most videos only show the ball and string bed.

The stiffness of the racquet affects all of these things to some degree. If you think about an extremely soft racquet made of rubber, the frame would absorb more of the impact energy and spare the ball, strings, and player’s arm much of the collision stress. At the other end, a racquet  made of steel or ultra stiff material will push the impact stress back to the strings and ball, and to some degree, the hand.

When they developed your racquet the designer not only had a target for the overall stiffness, they were also looking for the delicate balance between protecting your hand from vibration and allowing tactile feedback for you to know how the impact went.  There are numerous patented materials and techniques for “dampening” the vibrations in just the right way to match the demands of the targeted player. If you can imagine a raw beginner to the sport is happy enough just to hit the ball whereas a seasoned professional needs nuanced feedback.

Another characteristic of the stiffness spectrum is that there are two issues to consider. One is shock and the other is vibration. Shock happens at the instant of impact. With our hypothetical steel racquet, when it impacts a large force at one end it will send that energy immediately to the hand at the other end. Vibration comes when the racquet flexes like a pool noodle and waves of bending travel up and down the frame until they die out. Either of these types of force in extreme amounts can eventually cause arm issues.

Stiffness also impacts your tennis in other ways. When you are trying to react to a hundred mile an hour serve having a softer frame can help cushion the incoming energy. Too soft could make the ball uncontrollable but the right amount of flex coupled with a little extra overall weight can make returning serves more fun. Racquet designers typically use beam thickness to control the stiffness of the hoop. This is the thickness of the hoop perpendicular to the string bed when the racquet is placed on a table. A beam diameter of 20 mm is usually reserved for softer, heavier frames whereas a very stiff and light alternative can be double that. The Wilson Hammer line is a well-known example of a very thick, and therefore stiff beam.

To conclude, the individual characteristics that make your racquet unique are not important only by themselves, they also interact with one another to yield the end result. Weight impacts how much your hand feels at impact but that is in conjunction with how large the head is, and how stiff,  tight and thick the strings are. Where the weight is placed on the length of the frame and how stiff the hoop is are also ingredients in the mix.

Hopefully understanding what makes your racquet unique can help shine a light on that weapon you have in your hand as you try to get that one more ball back over the net. If you have any comments or questions I would love to hear from you.

Blog # 2 How I Believe Physical Learning Works in Tennis

Through more than 50 years playing and trying to understand the game of tennis, I've seen a lot of players plateau at the same level with their game for many  years until the ravages of time finally start them down the inevitable path towards aging out. Obviously their “game” consists of both a physical side that is stroke quality, and the mental side, which is understanding the strategies of the game. Sadly, I've known many players who could explain sound strategies and tactics but mostly fail to take advantage of that knowledge in the heat of competition. Yes, I frequently consider myself guilty of that error.

In today’s discussion, I am more focused on improving the physical aspect of one’s game, so when you attempt to hit the ball that one more time over the net, it goes where you want. My favourite analogy for the physical learning process is throwing a ball at a hypothetical target on the wall. The first toss may hit the wall high and right of the target. If you are trying to grow the skill of hitting a target with a thrown ball, after that first missed toss you will try a second ball, allowing your learning brain to make a correction based on the visual feedback from the first. If the second ball hits the wall low and to the left of the target, that tells you a couple of things. First, something up there in the grey matter was engaged enough that it knew how to adjust in the right direction, or to at least adjust our throw in another direction. Second, it has now given the brain more information to work with to achieve the goal of hitting the target which is is somewhere between those two misses. 

A great practice wall in Agassiz, BC

After a hundred more balls your errors will likely be much closer to the target, assuming you are still bringing the same level of commitment and focus to the challenge. It is also likely you’ll have hit the target dead centre a few times. Before you get tennis elbow patting yourself on the back, realize that skill is not now imprinted permanently into your DNA. This is just one step on the journey to making that throw reliable. Even for this relatively simple task, you are still an undetermined number of practice sessions away from complete mastery.

At risk of sounding like a real downer, tennis is not that simple. There is no single target, as targets vary constantly throughout a match. Throwing a ball from your hand is less complicated than directing it with an impact on the centre of a string bed situated 18 inches beyond the end of your grip. Prior to your attempt to hit a tennis ball with a racquet, that same brain engaged in hitting the target is now also having to calculate the trajectory of the incoming ball from the other side of the net. Sadly enough, your opponent is also doing whatever they can to make that calculation more difficult with combinations of spin, power, and just plain good shots. Piled on top of all that is the fact that you have to move to intercept the incoming ball, making the targeting calculation exponentially more complicated for you and your brain. Why don't we all just quit now?!! 

To step back from the edge, we should all be quite happy that we ever hit the targets we do as recreational players that do this for fun on weekends (and weekdays if we are so lucky). But how can we up our targeting game? First, recognize that a tennis game does not allow for the repetitive practice that the earlier ‘target on the wall’ analogy does. After you miss just outside the line to the right, your opponent is not likely to hit you that exact same ball to let you try again. I would venture to say they probably couldn't get it close enough to the original shot even if they wanted to. This means your brain doesn't get that second throw to learn from, let alone the hundred it would take to make a measurable difference. Basically, when you play a tennis match, you are dancing with the skills you brought to the party.

I am a firm believer that improving your physical stroke skills takes practice outside of the game situation. As an example, you may get 3 or 4 overhead opportunities in a set. If you miss half of them because you couldn't get into position properly or the ball was spinning with backspin at 1500 RPM, your brain didn't learn anything. Well, except that it should ratchet up the stress levels when it sees a high ball in the air – like chickens when an eagle flies overhead. The value of practice always seemed obvious to me when I was young, but I really didn't think about why. Maybe I just had nothing better to do, but I always enjoyed spending hours at the local practice wall. The obvious bonus is not having to arrange a human practice partner and the wall never misses. Here are some things to think about for making your practice as effective as possible.

Returning to our target on a wall analogy, our brain can learn things to move our physical skills forward. These ideas can apply whether you are hitting against a wall, practice partner, or a ball machine.

#1 – Always have a target.

 This certainly applies when you are trying to groove a stroke – you may have heard the  maxim “don't practice until you get it right – practice until you can't get it wrong”.  Helping your brain by having a clear goal means it can tell that it missed and by how  much. That gives it the foundation to learning from correcting. In his book, The Inner Game of Tennis Timothy Gallwey¹  suggests that freeing the brain to do this in practice, rather than in a game when the outcome of the attempt matters to the score, makes the learning process easier. Remember, a target is not limited to that end result on the other end of the court. It can also be always hitting the ball in the middle of the strings or having your feet in position so your foundation is a solid platform on contact, every time.

 #2 – Minimize the variables to start.

A foundational term in education is scaffolding. It means completing the simple tasks first, giving you a base to build up to the more difficult. If you are trying to teach yourself how to hit a target it is much more difficult if your practice partner is trying to make you miss. That would be like attempting your ball toss at the hypothetical target at a full run with your back to the wall. You may make some headway, but it's probably not the easiest path to your goal of successful targeting. Build the speed and difficulty gradually so your attempts can be fluid and relaxed, rather than as a series of mini emergencies. Reducing things to their basic components right off the bat is not only a great way to start, but can also be the answer to dealing with a complex skill that has broken down and needs fixing.

#3 – Work on goals based on what your game needs.

A common mantra is “sometimes you win, sometimes you learn”. We all tally “unforced errors” - everyone does. The smart thing to do is keep track and look for patterns, your opponents may even be able to point them out to you if they are paying attention. If you decide a particular skill would really help your game if it were more reliable, break it down into its simplest components so you can make it successfully repeatable. In his book Muscle Memory and Imagery: Better Tennis, Dr. Archie Dan Smith²  argues that once you decide on the specific skill you are practicing it is best to work on that one thing only, until it is reliable. It might seem difficult – and monotonous – to see through, but he suggests at least a week of every other day for the skill to become reliably better for any length of time. I've heard it said that pros don't attempt shots they haven't grooved in practice. Perhaps when I've hit  over one million balls in a year, I will be less likely to try my low percentage “hail Mary” shots.

Parting Shot:

Something to keep in the back of your mind – one of the things that makes the memory of hard-earned skills begin to fade with time is not necessarily brain related. The human body is constantly regenerating itself. The learning brain that went through the practice last April and had that forehand impressively wired is now struggling to keep the ball in play. Hmm, it may have something to do with the fact that the player badly sprained their ankle in July and tore a meniscus in their opposite knee in September. Between those two injuries, and the resulting serious lack of exercise for eight months, when the brain tries to fire the same neurons it did in April and nothing is pushing back, it needs to go back to school with what it has to work with now. As the body changes, it's much like the loosening of strings that we talked about in blog episode 1.

I welcome your comments.

Mark

¹ Gallwey, W. T. (1974). The Inner Game of Tennis. Penguin Random House LLC. New York.

² Smith, A. D., MD (2017). Muscle Memory and Imagery: Better Tennis. CreateSpace. mmitennis.com

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Blog Edition 1: When should I change my strings?

The question I get asked most often as the “stringing guy” is “when should I change my strings?”

Other than the obvious answer - after breaking the existing strings - it's a question that requires some understanding and then making a decision only you can make for your tennis. A little knowledge can really help with that.

An important thing to know about tennis strings is they are constantly stretching and relaxing. Once the machine pulls the end of the string to the set tension, it is clamped off and begins to relax. It's the nature of how strings work, not some weird defect. Different materials lose their tension at different rates, but eventually they all do, and it's always faster right after stringing and gradually slows down. This happens whether you hit a ball or not, although the impact from playing the game generally speeds up the process.

Throughout your tennis journey you will likely play with different racquets and certainly different strings. If you are paying attention, at some point you will decide you like your strings a certain way - they perform well for you and enhance your ability to play the game. They “feel” right. Professional players spend time defining what that means to them so they can have their racquets strung to match that “feel” the day before, or as close to the match as possible. They know they like to play with fresh strings because they've spent many, many hours honing their skills with a racquet strung just the way they like it.

For us mere mortals, the process is usually a bit different. For example, some of us can immediately tell the difference and appreciate when we have fresh strings, because it just seems easier to put the ball where we want to. Others get the fleeting feeling that a newly-strung racquet feels different, but soon forget about it. We might have a good (or even bad!?!?) day or two on the court with new strings, but soon that fades. While we are hitting tennis balls our strings are stretching and then snapping back, although over time they are losing tension. It's known as creep. Remember this process is faster in the beginning and then slows down over time.

There are gadgets and gizmos that can be used to measure how much your strings have relaxed. There are phone apps that measure the frequency of vibrations when you strike the string bed with something firm.

There are expensive machines in specialty shops that can measure how much energy

it takes to stretch the strings a small amount.  

There are also handheld devices, both electronic and manual, that give you some indication of how the string tension has changed since the last stringing. They are especially useful if you compare that to the reading from the instant the racquet came off the stringing machine.

To cycle back to the question in the title: why should you care about string creep? The answer: as string tension drops, the racquet plays differently. If the strings are now soft enough that the ball is staying on the string bed for one one-thousandth of a second longer, that can mean the difference between a ball landing inside the baseline or a foot and a half beyond. Fortunately for us, creep doesn't happen like a light switch; instead, it happens relatively slowly, again, faster initially and less obvious over time. Certain types of string also lose their tension at a slower rate than others.

If you are not someone hitting hard enough to break strings regularly, then it is possible your subconscious tennis brain will make adjustments as creep happens without you knowing about it. It will compensate for the changes in tension by changing the way you hit the ball. Few people I know will enjoy missing their targets day in and day out, so something subtle is going on as the strings age. The racquet is now training the player to hit differently in order to keep the ball in play. Fortunately, the changes slow down as the strings truly become “old”.

So, to get past axioms like “change your strings in a year as often as you play in a week”, or “time to change when the tension drops by 20%”, the decision comes down to your commitment level, and possibly your finances. If you appreciate playing with a newly-strung racquet then understand that feeling is finite. Not many recreational players can afford to have new strings every time they play like the professionals do. It's not really practical to think about unless you are stringing your own racquets and have a lot of time on your hands.

It comes down to, then, two ways of approaching strings:

1. You can try to chase a consistent string tension and be willing to make a point of getting them replaced at regular intervals. That will give your practice and play a consistency, so your equipment is always predictable.

2. You can just play with them until they break and accept that you will be playing with strings that change over time and will not perform the same as new.

The only point I would make about the latter option is there are lots of opinions on tennis blogs and articles saying that old strings can cause arm problems. In my stringing practice I have experienced people who come back for a restring when they start feeling pain in their arm. I need to be honest and say I have been unable to find a physiological reason for this to be the case in the research I have done. My gut tells me the strings should get softer as they loosen, so the impact with the ball should actually be less harsh. Assuming anecdotal information reflects reality, it could be that changes in stroke technique that come from playing with loose strings could potentially be the culprit. On the flip side, many people insist on playing with looser strings. That would frustrate me because I would miss the perceived control of firmer strings. Certainly, many advocates of lower tensions experience no issues with their arms or shoulders.

I would be very interested in hearing your thoughts on the matter.

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