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Strings (tennis)
Encyclopedia
In tennis, the strings are the part of a tennis racquet which make contact with the ball. The strings form a woven network inside the head (or "hoop") of the racquet. Strings have made with a variety of materials and possess varying properties that have been measured, such as dynamic stiffness, tension retention, thickness (gauge), string texture (shape of the string), and rebound efficiency.
Its principal drawbacks are much higher cost to manufacture and purchase than other materials, weakness to shear stresses from off-center hits (typical of beginning players), variable quality control depending upon the brand, batch, age, storage conditions, and grade, difficulty of stringing due to its delicacy, and poor durability when wetted with water. Some players, particularly those who hit flat shots and hit the sweet spot consistently, find high-quality gut to be more durable than many other types of strings due to its outstanding tension retention. This may help to offset the high initial cost. The use of a dense string pattern also generally improves the longevity of natural gut.
Natural gut is produced by drying fiber
s extracted from a part of the cow
intestine
called the serous membrane
, or serosa, which contains collagen
designed to withstand the stretching and contraction of the intestine. It is this elasticity that makes the fibers useful for tennis string. Sheep
intestines have also been used for racquet strings in the past.
The first natural gut tennis string was rumored to be manufactured in 1875 by Pierre Babolat
, who would launch the VS brand of gut fifty years later. Natural gut is usually offered in coated form, to reduce its tendency to unravel, particularly when humid or wet.
Small changes from pure nylon are usually found in strings sold as "synthetic gut". Textured coatings, colorants, and the addition of a small amount of Kevlar are the most common changes. Some manufacturers, such as Gosen, label nylon strings with words like "sheep", as in sheep intestine, although such strings contain no gut.
Synthetic gut, as it is used for mono-filament nylon strings, is now a misnomer, as the creation of multi-filament strings has provided players with a better approximation of natural gut's performance. Modern "synthetic gut" is actually a multi-filament string that holds its tension extremely well and which has a dynamic stiffness profile that is closest to natural gut, although the industry continues to apply the term to mono-filament nylon strings.
, but can incorporate other materials such as polyurethane
, Zyex, Vectran
, Kevlar, and other materials. Multi-filament strings offer better elasticity than single filament strings, but usually inferior durability. No multi-filament string holds its tension as well as natural gut, and none of them is as soft.
However, in comparison to mono-filament "synthetic gut", multi-filament strings can offer a much closer approximation of natural gut's performance. The softest multi-filament strings can be made with Zyex and polyolefin, although some of the softest of these strings are no longer on the market.
is a stiff and durable string material, originally intended for use by frequent string breakers. It took the string time to become popular, primarily due to its poor tension holding capability. However, due to the reduced potential for unwanted string movement, players are able to apply more topspin to balls while maintaining control. Polyester's support for heavy topspin in particular has made it the most popular material in the pro tour.
is the stiffest, most durable synthetic string available, and is thus extremely hard to break. It also has the poorest tension holding capability and is the most dangerous string when it comes to developing tennis elbow
. Kevlar is often strung with another string, such as nylon), in order to combine both strings' qualities, as Kevlar by itself feels too stiff for many tennis players, especially when combined with a stiff racquet. Some advocate using a very thin gauge Kevlar for increasing comfort, but even in the thinnest gauge it is a stiff string. Another strategy to increase comfort and improve rebound efficiency is to string Kevlar at a low tension.
is the penultimate string in terms of stiffness and durability. It is perhaps the least commonly used contemporary string material. It is usually added to nylon string to increase nylon's durability and stiffness, as with Kevlar. Yonex, for instance, offers two badminton strings, made primarily from nylon, which have Vectran strands. However, the Ashaway company offers a braided Vectran tennis string.
is one of the softest synthetic string materials, rivaling some Zyex and most nylon multi-filaments. It offers mediocre durability and tension retention, so it is generally used as the cross string in a hybrid string setup. For those who do not break strings very quickly, however, 100% polyolefin stringing may be a good alternative to natural gut and multi-filament strings. This is especially true for those who have had tennis elbow
and find natural gut string to be too costly.
Typically, a higher gauged string performs better. For example, the thinner 16-, 16L-, 17-, and 18 gauge strings are more lively and elastic than the thicker 15 or 15L. Thin strings are also known for better performance in creating spin and providing better feel. However, high-gauge strings also break faster, simply because there is less material to wear out.
Virtually all modern raquets are strung in a criss-cross horizontal-vertical pattern. Various other patterns have been used in history with varying success.
Double strung tennis racquets were introduced in 1977 but the "spaghetti racquets" were later banned because they permitted excessive spin and were too successful. However, a modern version of the double strung racquet has been introduced that is legal to use.
Racquets are strung either with two separate strings (and thus four knots), or with a single string (resulting in only two knots). Sometimes, a hybrid of two different string types may be used in the same racquet. Traditionally, a double half hitch
has been used to tie off tennis string, along with a starting knot
. Recently, a new kind of knot has been used called the "pro-knot" or "Richard Parnell knot". Along with the use of a starting clamp, this can make all the knots identical, and improve the aesthetics of a string job.
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, indicates the pressure under which the strings are secured to the frame. The string tension affects a racquet's playing characteristics, such as the "feel" of the ball, control over the ball, as well as maximizing power.
All racquets come with recommended string tensions, most of which lie between 50 to 70 pounds (220 to 310 N).
A loosely strung racquet will usually have a larger sweet spot and will hit farther but, when swung hard enough, it will shoot balls unpredictably; a tighter string job will help make delicate shots with more finesse and control.
An extremely tightly strung racquet cuts down on a tennis player's feel on the ball, but can give the player excellent control if swung hard enough, with a smooth stroke. Such tension may make delicate shots more difficult, but makes play from the baseline more constant. However, if a player often hits powerful shots, a tightly strung racquet may quickly tire the arm, possibly resulting in tennis elbow
.
It is advised by many professional stringers to string your racquet with the lowest tension possible while still being able to maintain control of the ball. Beginning players trying to find their tension should start in the middle of the recommended tension range and adjust the tension from there to meet their needs. The recommended tension is usually printed on the racquet. With a lower tension the racquet will have more power and less control; with a higher tension, it will have less power and more control.
The frequency of restringing depends on the player and the racquet, but there are a few recommended intervals. One is to restring the racquet as many times in a year as the player uses it in a week; e.g., if the racquet is used three times per week, it should be restrung three times per year. Another guideline is to restring after every 40 hours of play; if the racquet is used three times per week and three hours per session, it should be restrung approximately every five weeks. If the player has access to a tennis string tension meter (or access to a pro shop equipped with one), he may restring his racquet after he measures a loss of 25% or more of stringbed stiffness. However, many players who hit the ball hard to break the strings simply restring rackets whenever the strings break.
Since 2004, RSi, the USRSA's monthly magazine, has named a Stringer of the Year. Past winners were:
Composition
The material used in tennis string can significantly affect a player's performance, and even health. Several materials are used to make tennis strings. They vary in terms of elasticity, durability, rebound efficiency, tension holding capability, and manufacturing cost, among other considerations.Natural Gut
Animal intestine is the most resilient material used to make tennis strings. It has better tension retention than any other material, and also is softer than any other material used for tennis strings. It provides the most energy return, meaning it is the most efficient string. It remains soft at high tensions while other materials tend to dramatically stiffen. This allows gut string to enable players to string rather tightly to improve ball control without losing much rebound efficiency (power) and without greatly increasing impact shock, which can hurt the elbow and other joints.Its principal drawbacks are much higher cost to manufacture and purchase than other materials, weakness to shear stresses from off-center hits (typical of beginning players), variable quality control depending upon the brand, batch, age, storage conditions, and grade, difficulty of stringing due to its delicacy, and poor durability when wetted with water. Some players, particularly those who hit flat shots and hit the sweet spot consistently, find high-quality gut to be more durable than many other types of strings due to its outstanding tension retention. This may help to offset the high initial cost. The use of a dense string pattern also generally improves the longevity of natural gut.
Natural gut is produced by drying fiber
Fiber
Fiber is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.They are very important in the biology of both plants and animals, for holding tissues together....
s extracted from a part of the cow
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
intestine
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
called the serous membrane
Serous membrane
In anatomy, serous membrane is a smooth membrane consisting of a thin layer of cells which secrete serous fluid. Serous membranes line and enclose several body cavities, known as serous cavities, where they secrete a lubricating fluid which reduces friction from muscle movement...
, or serosa, which contains collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
designed to withstand the stretching and contraction of the intestine. It is this elasticity that makes the fibers useful for tennis string. Sheep
Domestic sheep
Sheep are quadrupedal, ruminant mammals typically kept as livestock. Like all ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. Although the name "sheep" applies to many species in the genus Ovis, in everyday usage it almost always refers to Ovis aries...
intestines have also been used for racquet strings in the past.
The first natural gut tennis string was rumored to be manufactured in 1875 by Pierre Babolat
Babolat
Babolat is a French tennis, badminton and squash equipment company, best known for its strings and tennis racquets which are used by several top players such as Li Na, Rafael Nadal, Kim Clijsters, Andy Roddick, Fernando González, Igor Andreev, Fabio Fognini, Leander Paes, Nicolás Lapentti,...
, who would launch the VS brand of gut fifty years later. Natural gut is usually offered in coated form, to reduce its tendency to unravel, particularly when humid or wet.
Synthetic Gut
Synthetic gut is nylon, nearly always composed of a single filament. It is a very inexpensive string to manufacture and is generally the least expensive string to purchase.Small changes from pure nylon are usually found in strings sold as "synthetic gut". Textured coatings, colorants, and the addition of a small amount of Kevlar are the most common changes. Some manufacturers, such as Gosen, label nylon strings with words like "sheep", as in sheep intestine, although such strings contain no gut.
Synthetic gut, as it is used for mono-filament nylon strings, is now a misnomer, as the creation of multi-filament strings has provided players with a better approximation of natural gut's performance. Modern "synthetic gut" is actually a multi-filament string that holds its tension extremely well and which has a dynamic stiffness profile that is closest to natural gut, although the industry continues to apply the term to mono-filament nylon strings.
Multi-filament, or "Multi"
Multi-filament strings, known commonly as "multis" are strings that have more than one filament. They are most commonly made of many filaments of nylonNylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
, but can incorporate other materials such as polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
, Zyex, Vectran
Vectran
Vectran is a manufactured fibre, spun from a liquid crystal polymer created by Celanese Acetate LLC and now manufactured by Kuraray Co., Ltd. Chemically it is an aromatic polyester produced by the polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid.- Properties...
, Kevlar, and other materials. Multi-filament strings offer better elasticity than single filament strings, but usually inferior durability. No multi-filament string holds its tension as well as natural gut, and none of them is as soft.
However, in comparison to mono-filament "synthetic gut", multi-filament strings can offer a much closer approximation of natural gut's performance. The softest multi-filament strings can be made with Zyex and polyolefin, although some of the softest of these strings are no longer on the market.
Nylon
Nylon is the most popular string material for amateur players due to its low cost and the improvement in elasticity offered by multi-filament strings. Wear-resistant coatings for nylon strings are common, especially with multi-filament strings, because the outer filaments tend to break first as the racquet is used.Polyester
PolyesterPolyester
Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
is a stiff and durable string material, originally intended for use by frequent string breakers. It took the string time to become popular, primarily due to its poor tension holding capability. However, due to the reduced potential for unwanted string movement, players are able to apply more topspin to balls while maintaining control. Polyester's support for heavy topspin in particular has made it the most popular material in the pro tour.
Kevlar
KevlarKevlar
Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...
is the stiffest, most durable synthetic string available, and is thus extremely hard to break. It also has the poorest tension holding capability and is the most dangerous string when it comes to developing tennis elbow
Tennis elbow
Lateral epicondylitis or lateral epicondylalgia, also known as tennis elbow, shooter's elbow and archer's elbow, is a condition where the outer part of the elbow becomes sore and tender...
. Kevlar is often strung with another string, such as nylon), in order to combine both strings' qualities, as Kevlar by itself feels too stiff for many tennis players, especially when combined with a stiff racquet. Some advocate using a very thin gauge Kevlar for increasing comfort, but even in the thinnest gauge it is a stiff string. Another strategy to increase comfort and improve rebound efficiency is to string Kevlar at a low tension.
Vectran
VectranVectran
Vectran is a manufactured fibre, spun from a liquid crystal polymer created by Celanese Acetate LLC and now manufactured by Kuraray Co., Ltd. Chemically it is an aromatic polyester produced by the polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid.- Properties...
is the penultimate string in terms of stiffness and durability. It is perhaps the least commonly used contemporary string material. It is usually added to nylon string to increase nylon's durability and stiffness, as with Kevlar. Yonex, for instance, offers two badminton strings, made primarily from nylon, which have Vectran strands. However, the Ashaway company offers a braided Vectran tennis string.
Zyex
Zyex string offers more rebound efficiency, i.e. gut-like dynamic stiffness, than other synthetic strings, particularly when strung at low tensions. This gives it playability that is more similar to natural gut than, arguably, other synthetic materials. It also has low overall stiffness. The Pro Kennex IQ Element Z string, for instance, has the lowest stiffness of any synthetic string yet tested. The drawback of Zyex is that the outer wrapping materials in Zyex tennis string tend to be much less durable than the Zyex filaments inside the string and do not bond with them. This can lead to the outer wrapping wearing away, leaving the inner Zyex filaments.Polyolefin
PolyolefinPolyolefin
A polyolefin is a polymer produced from a simple olefin as a monomer. For example, polyethylene is the polyolefin produced by polymerizing the olefin ethylene. An equivalent term is polyalkene; this is a more modern term, although polyolefin is still used in the petrochemical industry...
is one of the softest synthetic string materials, rivaling some Zyex and most nylon multi-filaments. It offers mediocre durability and tension retention, so it is generally used as the cross string in a hybrid string setup. For those who do not break strings very quickly, however, 100% polyolefin stringing may be a good alternative to natural gut and multi-filament strings. This is especially true for those who have had tennis elbow
Tennis elbow
Lateral epicondylitis or lateral epicondylalgia, also known as tennis elbow, shooter's elbow and archer's elbow, is a condition where the outer part of the elbow becomes sore and tender...
and find natural gut string to be too costly.
The Gauge
The "gauge" number determines the thickness of the string. A string rated with a high gauge number is a thinner string; some gauge ratings also have a "Light" version, which is referred to by placing an "L" after the original rating's number (e.g., "15L"). Strings are usually rated at one of five common gauges; 15 (thickest), 15L, 16, 16L, and 17 (thinnest). String gauge is usually not of much concern to beginning tennis players, but can be very important to advanced and professional players.Typically, a higher gauged string performs better. For example, the thinner 16-, 16L-, 17-, and 18 gauge strings are more lively and elastic than the thicker 15 or 15L. Thin strings are also known for better performance in creating spin and providing better feel. However, high-gauge strings also break faster, simply because there is less material to wear out.
Stringing pattern
Double strung tennis racquets were introduced in 1977 but the "spaghetti racquets" were later banned because they permitted excessive spin and were too successful. However, a modern version of the double strung racquet has been introduced that is legal to use.
Racquets are strung either with two separate strings (and thus four knots), or with a single string (resulting in only two knots). Sometimes, a hybrid of two different string types may be used in the same racquet. Traditionally, a double half hitch
Half hitch
The half hitch is a simple overhand knot, where the working end of a line is brought over and under the standing part. Insecure on its own, it is a valuable component of a wide variety of useful and reliable hitches, bends, and knots....
has been used to tie off tennis string, along with a starting knot
Knot
A knot is a method of fastening or securing linear material such as rope by tying or interweaving. It may consist of a length of one or several segments of rope, string, webbing, twine, strap, or even chain interwoven such that the line can bind to itself or to some other object—the "load"...
. Recently, a new kind of knot has been used called the "pro-knot" or "Richard Parnell knot". Along with the use of a starting clamp, this can make all the knots identical, and improve the aesthetics of a string job.
Stringing
The process of installing strings in the racquet is called "stringing," and is done with a racquet string machine. These machines vary in complexity, accuracy and price. Stringing a racquet can take up to an hour for a novice, or around twenty minutes for a skilled stringer; during professional tournament a very skilled stringer may be asked to string a racquet while the player is on court. These stressful string jobs may not even take 10 minutes for a seasoned tournament stringer.Drop Weight stringers
These inexpensive stringers use a weighted bar to achieve the desired string tension. They are the smallest of all stringing machines, making them the easiest to transport. This, plus their affordability, makes them popular among those beginning to learn racquet stringing. However, they take much longer than other stringers, and so are impractical for professionals.Manual crank (lockout) stringers
These stringers use a crank to achieve the proper tension, at which point it locks into place. These stringers allow racquets to be strung quickly.Electronic Stringers
These stringers control the tension with a computer-directed electric motor. This is the most common kind of stringer found in stores and pro shops, but is also the most expensive. There are 2 types of electronic tension: constant pull and lock out. Constant pull, as the name suggests, pulls the string and continues pulling until the desired tension is reached making stringing more consistent and accurate as they compensate for the string stretching, the clamp loosing and slippage. Lock out electronics are similar if not the same as cranks; they will pull to your desired tension and will pull no more. Therefore lock outs are not as accurate as the constant pulls because they don't compensate for tension loss.String Tension
The "string tension" of a racquet, usually expressed in poundsPound-force
The pound force is a unit of force in some systems of measurement including English engineering units and British gravitational units.- Definitions :...
, indicates the pressure under which the strings are secured to the frame. The string tension affects a racquet's playing characteristics, such as the "feel" of the ball, control over the ball, as well as maximizing power.
All racquets come with recommended string tensions, most of which lie between 50 to 70 pounds (220 to 310 N).
A loosely strung racquet will usually have a larger sweet spot and will hit farther but, when swung hard enough, it will shoot balls unpredictably; a tighter string job will help make delicate shots with more finesse and control.
An extremely tightly strung racquet cuts down on a tennis player's feel on the ball, but can give the player excellent control if swung hard enough, with a smooth stroke. Such tension may make delicate shots more difficult, but makes play from the baseline more constant. However, if a player often hits powerful shots, a tightly strung racquet may quickly tire the arm, possibly resulting in tennis elbow
Tennis elbow
Lateral epicondylitis or lateral epicondylalgia, also known as tennis elbow, shooter's elbow and archer's elbow, is a condition where the outer part of the elbow becomes sore and tender...
.
It is advised by many professional stringers to string your racquet with the lowest tension possible while still being able to maintain control of the ball. Beginning players trying to find their tension should start in the middle of the recommended tension range and adjust the tension from there to meet their needs. The recommended tension is usually printed on the racquet. With a lower tension the racquet will have more power and less control; with a higher tension, it will have less power and more control.
Restringing
Due to the tension present on the strings, elasticity and tension begins to decrease the moment they are installed in a racquet. "Dead strings", or strings which have lost their tension, cut down on the performance of a racquet. Dead strings may also hamper a tennis player's ability to generate power and pace, and may even make their arm sore.The frequency of restringing depends on the player and the racquet, but there are a few recommended intervals. One is to restring the racquet as many times in a year as the player uses it in a week; e.g., if the racquet is used three times per week, it should be restrung three times per year. Another guideline is to restring after every 40 hours of play; if the racquet is used three times per week and three hours per session, it should be restrung approximately every five weeks. If the player has access to a tennis string tension meter (or access to a pro shop equipped with one), he may restring his racquet after he measures a loss of 25% or more of stringbed stiffness. However, many players who hit the ball hard to break the strings simply restring rackets whenever the strings break.
United States Racquet Stringers Association
The United States Racquet Stringers Association (USRSA) offers two levels of certification for stringers: the Certified Stringer and the Master Racquet Technician, of which around 350 exist worldwide. The Master Racquet Technician certification process includes testing of the stringer's ability to string a racquet, perform grip work, identify mistakes in an improperly strung racquet, and pass a written test that covers not only strings, but racquet technology as well.Since 2004, RSi, the USRSA's monthly magazine, has named a Stringer of the Year. Past winners were:
- Randy Stephenson, Texas (2004)
- Bob Patterson, Alabama (2005)
- Grant Morgan, Tennessee (2006)
- Tim Strawn, Virginia (2007)
- Nate Ferguson, (2008)
- Ron Rochi, Illinois (2009)
- Tom Parry, Minnesota (2010)