# Tension is not as significant a spec as you would think

#### PistolPete23

##### Rookie
The more important spec is string stiffness at a given tension, defined as the incremental amount of force needed to further stretch the string a little amount, usually measured in lbs/inch. In other words, stiffness determines the mechanical response of the string, not the tension, even though there is obvious correlation between tension and stiffness for a given string. Perhaps this is obvious to some people, but since I was a kid, I had always incorrectly referred to string tension as an absolute metric for comparison. I had stopped playing consistently around 2007 when I graduated from college and, when I returned to the sport 10+ years later, was shocked to discover that people were now stringing their racquets at tensions below 50 lbs. I used to string my racquets at 60-62 lbs. with synthetic gut and it was unthinkable that any decent player could keep their shots in the court with anything less than 55 lbs. At some point it dawned on me that because poly strings are inherently stiffer, in order for them to feel comparable to a nylon string or natural gut, you have to string at a much lower tension. This revelation that stiffness is the dominant metric also made me consider that perhaps "stiff" polys could be as comfortable as multifilament nylon, as long as the tension is low enough; that is, polys are only bad for your elbows if you allow them to be stiff by using a tension that's too high.

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#### esm

##### Semi-Pro
That is true. I have recently fell in love with low tension on fullbed of soft co-poly, in the low 30’s range. It is as comfortable as fullbed of syn gut at mid 50’s on the exact same racquet/same setup

#### PistolPete23

##### Rookie
If I had the tension vs stretch-displacement curve for every string in TW's database (similar to a stress vs strain curve for uniaxial tension), I could theoretically write a program that outputs an equivalent tension for string A, given string B is strung at xx lbs. It would be a pretty neat tool for players experimenting with different strings. For example, if you like the comfort of a racquet strung at 57 lbs. with Gosen Sheep Micro 16 and you wanted to try Volkl Cyclone 17, the program would tell you the equivalent tension to string at for Volkl Cyclone 17. It would be more precise than following empirical guidelines like "drop 5 lbs if going from synthetic gut to poly".

#### ByeByePoly

##### G.O.A.T.
, polys are only bad for your elbows if you allow them to be stiff by using a tension that's too high.
No ... poly is plastic ... plastic doesn’t stretch like nylon at any tension. You can poly-compensate ... lower tensions, heavier racquet ... never miss the sweet spot ... restring more often ... but you can’t make the plastic have nylon string stretch properties and longevity.

It’s a different question if you can play with poly and avoid injury ... all of our swings and elbows vote differently. My elbow never twinged once with RPM Blast 16g @52 for 5 years. It then skipped the twinge stage and went straight to 8 months off from tennis with bad TE.

All just fyi ... poly/plastic is greater elbow risk but worth the risk for some. Think about a string that you can keep in the court @30lbs ... only possible if it doesn’t have much elasticity.

#### PistolPete23

##### Rookie
No ... poly is plastic ... plastic doesn’t stretch like nylon at any tension. You can poly-compensate ... lower tensions, heavier racquet ... never miss the sweet spot ... restring more often ... but you can’t make the plastic have nylon string stretch properties and longevity.

It’s a different question if you can play with poly and avoid injury ... all of our swings and elbows vote differently. My elbow never twinged once with RPM Blast 16g @52 for 5 years. It then skipped the twinge stage and went straight to 8 months off from tennis with bad TE.

All just fyi ... poly/plastic is greater elbow risk but worth the risk for some. Think about a string that you can keep in the court @30lbs ... only possible if it doesn’t have much elasticity.
Polyester and nylon are both polymers/plastic. They're chemically quite different so obviously have different modulus of elasticity or stiffness in their un-stretched state. I didn't make any claims about longevity or tension retention, but I contend that elastic response (stretch property) or stiffness between nylon and poly strings can be made similar by tuning the independent variable, tension. This can be easily illustrated with schematic tension vs stretch curves for the two materials.

Think about a string that you can keep in the court @30lbs ... only possible if it doesn’t have much elasticity.
With the above statement, you have supported my argument without being aware of it . Poly strings are inherently not as "elastic" as nylon strings, i.e. they're stiffer so they deflect less upon ball impact at the same string tension; with lowered string tension, a stiff poly can theoretically deflect the same amount as a nylon string. Now admittedly, a poly setup will never completely feel the same as a nylon setup. There are other variables like impact dwell time and vibration dampening, but my hunch is that many people who complain about polys causing TE are stringing their racquets too tight.

#### ByeByePoly

##### G.O.A.T.
Good luck ... is PistolPete a Oklahoma State Cowboys reference?

#### PistolPete23

##### Rookie
Schematic to illustrate how a higher tension for poly strings will produce a similar stiffness response for nylon strings. At each point in the curve, the stretch response (i.e. stiffness) is given by the slope of the tangent to the curve. A poly string at a lower tension can have the same elastic stiffness (slope of tangent line) as a synthetic gut at higher tension.

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#### BlueB

##### Legend
No ... poly is plastic ... plastic doesn’t stretch like nylon at any tension.
I've got news for you... Nylon is a plastic.

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#### PistolPete23

##### Rookie
Good luck ... is PistolPete a Oklahoma State Cowboys reference?
Pistol Pete Sampras . Or Pistol Pete Maravich. Both are legends

#### ByeByePoly

##### G.O.A.T.
Schematic to illustrate how a higher tension for poly strings will produce a similar stiffness response for nylon strings. At each point in the curve, the stretch response (i.e. stiffness) is given by the slope of the tangent to the curve. A poly string at a lower tension can have the same elastic stiffness (slope of tangent line) as a synthetic gut at higher tension.

For how many hits?

The first hit with a tightly strung rubberband and one with taffy might be equally arm friendly on first hit.

#### ByeByePoly

##### G.O.A.T.
I've got news for you... Nylon is a plastic.

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Fake news.

#### PistolPete23

##### Rookie
For how many hits?

The first hit with a tightly strung rubberband and one with taffy might be equally arm friendly on first hit.
I've been hitting hard against a wall with a full poly setup at low tension; no elbow pain issues, but given your username, I don't expect you'll be convinced enough to try poly again

#### ByeByePoly

##### G.O.A.T.
I've been hitting hard against a wall with a full poly setup at low tension; no elbow pain issues, but given your username, I don't expect you'll be convinced enough to try poly again
My question was regarding your deflection matching by dropping poly tension. Let's say rpm blast 16g @52lbs is equal to Wilson Sensation @60lbs fresh off the stringer. Is deflection equal for both until the strings break? Or ... at least for 10-20 hours for those that will restring poly often? The strings properties over time/hours comes into play unless the string stays safe until restringing. I could play Velocity for 50 hours if it didn't break ... and I would not worry. RPM ... no.

I read an interesting observation/challenge to traditional belief in stretching (muscles/tendons). All of our muscles and tendons are already the right length for the bones and joints they are attached to ... so why would you try and make them longer. If you think of muscles/tendons as rubberbands ... you don't stretch the rubberband to keep it healthy. When a rubberband loses it's properties and becomes brittle that the problem. So ... instead of stretching, drink more water.

Yes ... my name gives it away ... no more poly for ByeBye. The TE scared me ... thought there was a chance my tennis was over. I need my tennis ... after 40+ years of tennis, it's like oxygen and eating.

#### am1899

##### Hall of Fame
Lowering the tension only solves one part of a multi sided problem. Many of the manufacturers of polyester strings already tell consumers to string their polyester strings lower than anything else.

Lowering the tension doesn’t address how these 2 different strings age as they are used. For most people, it’s perfectly fine to play nylon synthetic gut until it breaks. Not so with polyester.

#### am1899

##### Hall of Fame
I guess my point is, the potential ability to calculate the equivalency of tension between a nylon string and a polyester string is only good for the moment both racquets come off the stringing machine. Once those two string beds start aging, because of the differences of the strings’ properties, equivalence is out the window.

#### ByeByePoly

##### G.O.A.T.
I guess my point is, the potential ability to calculate the equivalency of tension between a nylon string and a polyester string is only good for the moment both racquets come off the stringing machine. Once those two string beds start aging, because of the differences of the strings’ properties, equivalence is out the window.
I hear an echo

#### esgee48

##### Legend
Polyester polymers make non-elastic plastic strings. Stretches permanently with ball impacts once off the stringing machine. Nylon strings make much more elastic strings that stretch, but most is recovered depending on ball impact forces. Playable polyester longevity is << 16 hours. Nylon based longevity can be adjusted with tension and gauge. It can be all over the map due to player since they can last < 2 hours all the way to months or years.

OP is saying very little new. A range DT values for the string bed is what determines player comfort and string performance. Polyester needs low ref tension to have similar DT of nylon based strings at higher ref tension. The tension differential is not fixed. It is based on player, frame, string and temperature/environment.

The only way I can achieve comparable DTs is to find those ref tensions, so I would disagree with OP. My machine does not have a DT setting, but it does have a lb/Kg setting. It is up to the stringer to help the player find the tensions that give them the same feel. To me, that means at least 2 string jobs for a new client.

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#### ByeByePoly

##### G.O.A.T.
Polyester polymers make non-elastic plastic strings. Stretches permanently with ball impacts once off the stringing machine. Nylon strings make much more elastic strings that stretch, but most is recovered depending on ball impact forces. Playable polyester longevity is << 16 hours. Nylon based longevity can be adjusted with tension and gauge. It can be all over the map due to player since they can last < 2 hours all the way to months or years.

OP is saying very little new. A range DT values for the string bed is what determines player comfort and string performance. Polyester needs low ref tension to have similar DT of nylon based strings at higher ref tension. The tension differential is not fixed. It is based on player, frame, string and temperature/environment.

The only way I can achieve comparable DTs is to find those ref tensions, so I would disagree with OP. My machine does not have a DT setting, but it does have a lb/Kg setting. It is up to the stringer to help the player find the tensions that give them the same feel. To me, that means at least 2 string jobs for a new client.
Two string jobs? A good stringer would nail it one ... they would know what the player needs just looking at them.

#### esgee48

##### Legend
For established clients with known-to-me characteristics (technique, frame, etc.,) I can generally hit it in one whenever they want to trial a new string. Harder to do so with a new frame; much harder with new frame and string trials. I also like to see new clients in action rather than rely on their own descriptions of playing level. Accomplished players are generally more picky (make that very picky) about tension. [/sarcasm] People who don't find the sweet spot all the time, generally do not care as much. [/end sarcasm]

#### ByeByePoly

##### G.O.A.T.
For established clients with known-to-me characteristics (technique, frame, etc.,) I can generally hit it in one whenever they want to trial a new string. Harder to do so with a new frame; much harder with new frame and string trials. I also like to see new clients in action rather than rely on their own descriptions of playing level. Accomplished players are generally more picky (make that very picky) about tension. [/sarcasm] People who don't find the sweet spot all the time, generally do not care as much. [/end sarcasm]
Picky tennis players ... pita!!!

I have a bad cold ... ignore everything I type

#### PistolPete23

##### Rookie
I guess my point is, the potential ability to calculate the equivalency of tension between a nylon string and a polyester string is only good for the moment both racquets come off the stringing machine. Once those two string beds start aging, because of the differences of the strings’ properties, equivalence is out the window.
The property with polyester that causes loss of tension is called mechanical hysteresis, of which I’m well aware of. Both nylon and gut are better at retaining tension, while polyester loses noticeably more with every hit, so you are correct that the equivalence is "lost" once the strings come off the machine and upon the first hit with the poly setup. But if you study the load-unload characteristics of poly strings, as the poly loses tension, it actually becomes softer, so poly strings “going dead” does not make it harsher on the arm; it just means after extended play you have a racquet that becomes very different from the starting point. The purpose of my OP was not to suggest that all the problems with poly can be solved by tension tuning, only that if you’re set on reaping the benefits of poly (more access to spin), it doesn’t have to carry a higher risk of injury.

#### LOBALOT

##### Semi-Pro
Picky tennis players ... pita!!!

I have a bad cold ... ignore everything I type
I have the same gosh darn flu. Plugged Up, Sneezing, Coughing, Fever, Chills... awful.

After seeing the cold reference I guess I need to jump in.

I agree with esgee48 in that it depends on the material/string. Some strings, it doesn't mater how low you go the material is inherently stiff.

#### LOBALOT

##### Semi-Pro
The property with polyester that causes loss of tension is called mechanical hysteresis, of which I’m well aware of. Both nylon and gut are better at retaining tension, while polyester loses noticeably more with every hit, so you are correct that the equivalence is "lost" once the strings come off the machine and upon the first hit with the poly setup. But if you study the load-unload characteristics of poly strings, as the poly loses tension, it actually becomes softer, so poly strings “going dead” does not make it harsher on the arm; it just means after extended play you have a racquet that becomes very different from the starting point. The purpose of my OP was not to suggest that all the problems with poly can be solved by tension tuning, only that if you’re set on reaping the benefits of poly (more access to spin), it doesn’t have to carry a higher risk of injury.
What about elasticity??? That certainly decreases.

So while the tension is lost as the string is permanently deformed the elasticity is lost as well.

#### fjcamry

##### Semi-Pro
The kirschbaum proline ll in 17L (1.20) with 16g multifibre cross strung at 54/57 can behave just as the same as kirschbaum xplosive 17g (1.25) mains at same tension . Because tw stiffness ratings are 192 versus 186 for these strings . However because of the 17L gauge and red color of proline ll might make it feel little more lively than the black 17g of xplosive. I made it as control as possible comparisons with these strings

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#### PistolPete23

##### Rookie
Polyester polymers make non-elastic plastic strings. Stretches permanently with ball impacts once off the stringing machine. Nylon strings make much more elastic strings that stretch, but most is recovered depending on ball impact forces. Playable polyester longevity is << 16 hours. Nylon based longevity can be adjusted with tension and gauge. It can be all over the map due to player since they can last < 2 hours all the way to months or years.

OP is saying very little new. A range DT values for the string bed is what determines player comfort and string performance. Polyester needs low ref tension to have similar DT of nylon based strings at higher ref tension. The tension differential is not fixed. It is based on player, frame, string and temperature/environment.

The only way I can achieve comparable DTs is to find those ref tensions, so I would disagree with OP. My machine does not have a DT setting, but it does have a lb/Kg setting. It is up to the stringer to help the player find the tensions that give them the same feel. To me, that means at least 2 string jobs for a new client.
The tension-displacement curves can potentially be measured and stored in a database. Then if a client comes to you and say, "hey, I've been playing with the Gamma TNT strung at xx lbs. for a decade and really have no reason to switch, but I really want to try a particular poly", it would be reasonable to look up at what tension the poly would have a similar dynamic stiffness as the Gamma string instead of having to rely purely on intuition and experience.

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#### ByeByePoly

##### G.O.A.T.
I have the same gosh darn flu. Plugged Up, Sneezing, Coughing, Fever, Chills... awful.

After seeing the cold reference I guess I need to jump in.

I agree with esgee48 in that it depends on the material/string. Some strings, it doesn't mater how low you go the material is inherently stiff.
Oh ... you have it worse ... I just have a cold ... lost my voice for a while. Wife liked that ... not nice.

I always agree with @esgee48 unless I have a cold.

Mechanical hysteria ... wtf ... I am going to bed.

#### LOBALOT

##### Semi-Pro
Oh ... you have it worse ... I just have a cold ... lost my voice for a while. Wife liked that ... not nice.

I always agree with @esgee48 unless I have a cold.

Mechanical hysteria ... wtf ... I am going to bed.
I agree, me too! I am headed upstairs!

I hope you feel better!

#### chic

##### Rookie
The property with polyester that causes loss of tension is called mechanical hysteresis, of which I’m well aware of. Both nylon and gut are better at retaining tension, while polyester loses noticeably more with every hit, so you are correct that the equivalence is "lost" once the strings come off the machine and upon the first hit with the poly setup. But if you study the load-unload characteristics of poly strings, as the poly loses tension, it actually becomes softer, so poly strings “going dead” does not make it harsher on the arm; it just means after extended play you have a racquet that becomes very different from the starting point. The purpose of my OP was not to suggest that all the problems with poly can be solved by tension tuning, only that if you’re set on reaping the benefits of poly (more access to spin), it doesn’t have to carry a higher risk of injury.
I thought the current understanding was that as poly goes dead it stops snapping back. Since the strings are no longer oscillating as much to snap back more force is being dissipated into the frame (and therefore the arm) all at once which is why it is harsher on the arm?

Edit: I may be misinformed, but I don't know where I would have come up with that otherwise

#### chic

##### Rookie
Still team poly though

#### MisterP

##### Hall of Fame
The more important spec is string stiffness at a given tension, defined as the incremental amount of force needed to further stretch the string a little amount, usually measured in lbs/inch. In other words, stiffness determines the mechanical response of the string, not the tension, even though there is obvious correlation between tension and stiffness for a given string. Perhaps this is obvious to some people, but since I was a kid, I had always incorrectly referred to string tension as an absolute metric for comparison. I had stopped playing consistently around 2007 when I graduated from college and, when I returned to the sport 10+ years later, was shocked to discover that people were now stringing their racquets at tensions below 50 lbs. I used to string my racquets at 60-62 lbs. with synthetic gut and it was unthinkable that any decent player could keep their shots in the court with anything less than 55 lbs. At some point it dawned on me that because poly strings are inherently stiffer, in order for them to feel comparable to a nylon string or natural gut, you have to string at a much lower tension. This revelation that stiffness is the dominant metric also made me consider that perhaps "stiff" polys could be as comfortable as multifilament nylon, as long as the tension is low enough; that is, polys are only bad for your elbows if you allow them to be stiff by using a tension that's too high.
I experimented with Volkl Cyclone in the low 40s and high 30s and I found the string response pretty erratic. Tremendous spin, but unpredictable. I could probably dial it in with enough time but why? I don’t have TE and I’m happy with my poly at 52 lbs.

#### 3virgul14

##### Rookie
I have strung 1.25 Cyclone on my Fischer 42x36lbs to maximize the spin and comfort. The result was a surprise because it has enough power, cutting through the ball really well during the serves and good for baseline topspin shots.

Though the feel for drop shots or net volleys is a different story. Cant manage neither at all.

#### 34n

##### Rookie
Polyester polymers make non-elastic plastic strings. Stretches permanently with ball impacts once off the stringing machine. Nylon strings make much more elastic strings that stretch, but most is recovered depending on ball impact forces.
My understanding is that poly string have properties of a spring, while nylon are more like a rubber band.
The more you stretch the rubber band the more stiff it becomes. It stretches until it breaks eventually.
Spring (poly) is stretched without changing stiffness until a certain limit. Until you stretch out all the coils and the spring becomes a steel wire which does not stretch further.
When you define tension of a poly you want to be within the spring range, not to overstretch it when it becomes an equivalent of a steel wire.
When you select a gauge you want an optimal spring stiffness for your strokes - to stay inside the springy zone on your softest and hardest strokes.

When you hear a loud bang playing with a poly it means your shot caused the string to stretch out of spring zone and become a steel wire for a moment. Also this is the moment when you do most of the permanent damage to the string. Eventually all "coils" are stretched out and the "spring" becomes a non-elastic steel wire aka "dead poly".

#### am1899

##### Hall of Fame
The property with polyester that causes loss of tension is called mechanical hysteresis, of which I’m well aware of. Both nylon and gut are better at retaining tension, while polyester loses noticeably more with every hit, so you are correct that the equivalence is "lost" once the strings come off the machine and upon the first hit with the poly setup. But if you study the load-unload characteristics of poly strings, as the poly loses tension, it actually becomes softer, so poly strings “going dead” does not make it harsher on the arm; it just means after extended play you have a racquet that becomes very different from the starting point. The purpose of my OP was not to suggest that all the problems with poly can be solved by tension tuning, only that if you’re set on reaping the benefits of poly (more access to spin), it doesn’t have to carry a higher risk of injury.
Forgive me, am I the student, and you are the teacher?

Anyway...I wasn’t talking about tension loss when I referred to strings aging, and their respective properties.

But look, if writing this equivalence program creams your Twinkie, have at it.

#### PistolPete23

##### Rookie
Forgive me, am I the student, and you are the teacher?

Anyway...I wasn’t talking about tension loss when I referred to strings aging, and their respective properties.

But look, if writing this equivalence program creams your Twinkie, have at it.
No, I’m not the teacher and you’re not the student, and neither is it the other way around. If I came across as arrogant, I apologize; having spent too many years in academia can have the effect of making one sound unintentionally like a professor, but I meant no offense; it’s just the way academic peers communicate but I now realize this forum is not appropriate for technical jargon etc. etc. I spoke of tension loss because it’s one of the most, if not the most, clearest manifestations of aging in strings, that’s all.

#### ByeByePoly

##### G.O.A.T.
The property with polyester that causes loss of tension is called mechanical hysteresis, of which I’m well aware of. Both nylon and gut are better at retaining tension, while polyester loses noticeably more with every hit, so you are correct that the equivalence is "lost" once the strings come off the machine and upon the first hit with the poly setup. But if you study the load-unload characteristics of poly strings, as the poly loses tension, it actually becomes softer, so poly strings “going dead” does not make it harsher on the arm; it just means after extended play you have a racquet that becomes very different from the starting point. The purpose of my OP was not to suggest that all the problems with poly can be solved by tension tuning, only that if you’re set on reaping the benefits of poly (more access to spin), it doesn’t have to carry a higher risk of injury.
"But if you study the load-unload characteristics of poly strings, as the poly loses tension, it actually becomes softer, so poly strings “going dead” does not make it harsher on the arm; it just means after extended play you have a racquet that becomes very different from the starting point."

During those 5 years of RPM Blast, I never broke it and would play it for up to 3 months (tennis 2-3 times a week) before restringing. It was awesome first match ... and then "something different" as you said. There were many of my friends that played it for 3 months at a time ... none of us had ever been told we shouldn't (it was one of the reasons we used poly ... didn't have to get restrung is often). I think TE is often an injury from accumulated micro-tears over time, so I don't think playing poly for 3 months at a time or 5 years without TE makes the case it's as arm friendly as any other string. 35 years with sg and multi and multiple stiff racquets ... no TE. 5 years with poly ... TE.

BUT ... you may actually be correct that poly is no more risk to the arm in the 20th hour than the first hour, it just feels/plays different. It seems like if your data had both 1) the lower poly tension cross reference ... and 2) estimate of when that poly became "something different" it would be more useful for new poly buyers than tension maintenance stats.

I will help you with your first entry ... rpm blast becomes "something different" in 2 hours of BBP hitting ... probably 15 munutes of Nadal hitting.

#### ByeByePoly

##### G.O.A.T.
No, I’m not the teacher and you’re not the student, and neither is it the other way around. If I came across as arrogant, I apologize; having spent too many years in academia can have the effect of making one sound unintentionally like a professor, but I meant no offense; it’s just the way academic peers communicate but I now realize this forum is not appropriate for technical jargon etc. etc. I spoke of tension loss because it’s one of the most, if not the most, clearest manifestations of aging in strings, that’s all.
Not arrogant at all to me ... and we do technical here all the time (check out the endless posts on the ATP forehand ). This is a good discussion ... I believe poly has been a detriment to rec tennis ... but it's here and anything that makes it safer is of great value imo.

Prof ... fyi ... never apologize here ... it will confuse the herd.

#### PistolPete23

##### Rookie
Not arrogant at all to me ... and we do technical here all the time (check out the endless posts on the ATP forehand ). This is a good discussion ... I believe poly has been a detriment to rec tennis ... but it's here and anything that makes it safer is of great value imo.

Prof ... fyi ... never apologize here ... it will confuse the herd.
Maybe you’re right. I haven’t played with poly for 5 years but I did experience TE in the past with non-poly lol. But your experience of 5 years vs no TE after several decades is hard to ignore. Anyway, it’s a complicated thing, and I don’t think there’s a consensus for whether poly is bad for arm health.

#### am1899

##### Hall of Fame
No, I’m not the teacher and you’re not the student, and neither is it the other way around. If I came across as arrogant, I apologize; having spent too many years in academia can have the effect of making one sound unintentionally like a professor, but I meant no offense; it’s just the way academic peers communicate but I now realize this forum is not appropriate for technical jargon etc. etc. I spoke of tension loss because it’s one of the most, if not the most, clearest manifestations of aging in strings, that’s all.
Dang. I wanted to be the teacher for once! Just kidding.

Sorry that I came off offended. While I was responding here, I was in the midst of an unpleasant encounter with the IT dept. at my work. Regardless, it wasn’t fair for me to take it out on you. My apologies.

As for technical jargon - IMHO on the contrary, this is a place for that.

I definitely agree that tension loss is one of the most obvious changes a string bed undergoes - particularly with polyester.

#### am1899

##### Hall of Fame
Maybe you’re right. I haven’t played with poly for 5 years but I did experience TE in the past with non-poly lol. But your experience of 5 years vs no TE after several decades is hard to ignore. Anyway, it’s a complicated thing, and I don’t think there’s a consensus for whether poly is bad for arm health.
I don’t think polyester is inherently bad for arm health. I just think it is misunderstood. That is, if it is used properly, it’s not necessarily any more capable of causing (or exacerbating) an injury than some other types of strings on the market.

But by and large, the masses treat polyester like any other string - they play with it until it breaks. They don’t understand why they need to cut the strings out and restring at some point prior to the string breaking and/or they cannot justify the cost. But they want to play with what the pros are using - the magical strings they hear all about on tv. So round and round we go.

#### ByeByePoly

##### G.O.A.T.
Maybe you’re right. I haven’t played with poly for 5 years but I did experience TE in the past with non-poly lol. But your experience of 5 years vs no TE after several decades is hard to ignore. Anyway, it’s a complicated thing, and I don’t think there’s a consensus for whether poly is bad for arm health.
The science and medical fields still do not fully understand TE ... we are left with theory and anecdotal evidence. At this point, I put more weight in my actual experience and observation. I played tournaments and then USTA for 30+ years, and the bulk of that was opponents, teammates and club members with very light stiff racquets strung with sg or multi. I can't remember one elbow strap with the guys ... but did/do see them in ladies USTA. Then poly showed up ... some noticing new elbow and wrist soreness, a few got TE ... and several it hasn't bothered at all. There were many that tried poly one time and immediately cut it out and never tried it again. My group/peers are aging ... my TE was at 57, so have to consider age as a factor. Bottom line for me is I am convinced I could not have given myself TE with Wilson Sensation or Head Velocity strung mid-tension or lower if I tried.

#### Kevo

##### Legend
I think poly is a wide range of things. Most polys lose all their elasticity within a few hours of hitting. So low tension helps make them more arm friendly, but I can't imagine that the impact of hitting with a poly over a nylon string can be completely mitigated just by stringing lower. I can't recall a nylon string that ever lost it's elasticity completely.

I have been playing with polys for a long time now, and my tension is pretty low, but I am picky with the polys I use as I like to play them until they break. There are lots of polys I've found to be very harsh while others are quite comfortable. They all go dead though so I like to pick polys that reach their "dead" state after a short break in and then feel the same until they pop. I've been playing with that kind of poly for a long time now and haven't had any issues. I still would not recommend poly as a first choice. I'd say a nylon string is still probably the best first choice for most players. If you play enough though the durability issues with nylon become a real problem, so then it's an individual choice whether or not you can live with restringings all the time or need to go to something more durable.

Finally, the title of this thread seems off to me. If it's really the stiffness that's important and you can control how stiff the stringbed is with the tension you choose, then tension would seem to be pretty much as significant as most people think it is wouldn't it? Strings feel too stiff? Lower the tension. Strings feel too soft? Raise the tension.

Anyway, I do get that we have to jazz our thread titles with something that triggers the neurotransmitter hit or whatever, so kudos on that front.

#### PistolPete23

##### Rookie
I think poly is a wide range of things. Most polys lose all their elasticity within a few hours of hitting. So low tension helps make them more arm friendly, but I can't imagine that the impact of hitting with a poly over a nylon string can be completely mitigated just by stringing lower. I can't recall a nylon string that ever lost it's elasticity completely.

I have been playing with polys for a long time now, and my tension is pretty low, but I am picky with the polys I use as I like to play them until they break. There are lots of polys I've found to be very harsh while others are quite comfortable. They all go dead though so I like to pick polys that reach their "dead" state after a short break in and then feel the same until they pop. I've been playing with that kind of poly for a long time now and haven't had any issues. I still would not recommend poly as a first choice. I'd say a nylon string is still probably the best first choice for most players. If you play enough though the durability issues with nylon become a real problem, so then it's an individual choice whether or not you can live with restringings all the time or need to go to something more durable.

Finally, the title of this thread seems off to me. If it's really the stiffness that's important and you can control how stiff the stringbed is with the tension you choose, then tension would seem to be pretty much as significant as most people think it is wouldn't it? Strings feel too stiff? Lower the tension. Strings feel too soft? Raise the tension.

Anyway, I do get that we have to jazz our thread titles with something that triggers the neurotransmitter hit or whatever, so kudos on that front.
Re: title of thread. I’ve found that TTW often needs assertions that lies on the edge of controversy in order to get good dialogue going

#### ByeByePoly

##### G.O.A.T.
Maybe you’re right. I haven’t played with poly for 5 years but I did experience TE in the past with non-poly lol. But your experience of 5 years vs no TE after several decades is hard to ignore. Anyway, it’s a complicated thing, and I don’t think there’s a consensus for whether poly is bad for arm health.
I posted this in another thread ... I bet the prof can take my simple logic and elaborate:

At contact in tennis 4 things can "give/absorb":

1) ball
2) racquet
3) string
4) arm/hand/wrist

Let's say for a given player's technique and arm anatomy ... he runs into injury risk when x% of the give is offloaded to the arm.

How do we quantify/compare a racquets "give" vs strings "give"?

Racquet RA 50ish -> 75ish
String stiffness 100ish -> 250+ish

What provides more give ... a 50ish noodle racquet or a 100ish gut? I am going to say gut matters more based on my limited anecdotal evidence (have hit fb multis in a Pure Drive, fb gut in a Volkl 68 RA, rpm in a Yonex 69ish RA). Different flex points in racquets, and RA is deceiving because my Volkl V1 Pro 68 RA is the most arm friendly (muted) racquet I have hit. Maybe add above 5) Volkl grommet and handle tech.

What would be nice is to actually be able to calculate "racquet + string" give ... assuming racquet and string give is equal as far as arm risk is concerned.

Then ... muddy the waters with "vibrations" and racquet recoil and swing weight ... and no wonder those of us that showed up here with TE crowd sourced our racquet and string choices.

#### ByeByePoly

##### G.O.A.T.
I think poly is a wide range of things. Most polys lose all their elasticity within a few hours of hitting. So low tension helps make them more arm friendly, but I can't imagine that the impact of hitting with a poly over a nylon string can be completely mitigated just by stringing lower. I can't recall a nylon string that ever lost it's elasticity completely.

I have been playing with polys for a long time now, and my tension is pretty low, but I am picky with the polys I use as I like to play them until they break. There are lots of polys I've found to be very harsh while others are quite comfortable. They all go dead though so I like to pick polys that reach their "dead" state after a short break in and then feel the same until they pop. I've been playing with that kind of poly for a long time now and haven't had any issues. I still would not recommend poly as a first choice. I'd say a nylon string is still probably the best first choice for most players. If you play enough though the durability issues with nylon become a real problem, so then it's an individual choice whether or not you can live with restringings all the time or need to go to something more durable.

Finally, the title of this thread seems off to me. If it's really the stiffness that's important and you can control how stiff the stringbed is with the tension you choose, then tension would seem to be pretty much as significant as most people think it is wouldn't it? Strings feel too stiff? Lower the tension. Strings feel too soft? Raise the tension.

Anyway, I do get that we have to jazz our thread titles with something that triggers the neurotransmitter hit or whatever, so kudos on that front.
Yeah ... I'm glad I'm not a quick string breaker, non-poly arm friendly durable main is a very small list I would think. Maybe zx ... never tried it.

#### Kevo

##### Legend
Yeah ... I'm glad I'm not a quick string breaker, non-poly arm friendly durable main is a very small list I would think. Maybe zx ... never tried it.
ZX is durable in terms of abrasion, but it seems to be a bit more delicate in other ways. I think the feel is more tension sensitive than most strings though, so it's a bit finicky. I used to love the Klipper zyex string, but zyex on zyex is not much more durable than nylon on nylon. You really need to pair it up with something else for durability benefits.

#### ByeByePoly

##### G.O.A.T.
ZX is durable in terms of abrasion, but it seems to be a bit more delicate in other ways. I think the feel is more tension sensitive than most strings though, so it's a bit finicky. I used to love the Klipper zyex string, but zyex on zyex is not much more durable than nylon on nylon. You really need to pair it up with something else for durability benefits.
I never needed a more durable main than Velocity (or Origin, HDX, etc) in my tight 16x19 V1 Pro. I have two, and anything 15+ hours is an acceptable trip schedule to the stringer. That said ... my first arm friendly string test if I was a quick string breaker would be zx/multi. That is solely based on posts here from players that had to solve the durable non-poly main problem. Supposedly that hybrid removes the unpleasant ping of fb zx. Anyway ... I will never know ... fb Velocity is durable enough as long as I don't change to an open string pattern.

#### ByeByePoly

##### G.O.A.T.
@PistolPete23 ... your best theory test subjects will be TE elbow degraded players. Not current TE ... everything hurts ... not never had TE ... nothing hurts. You need to test your theory with players where any poly, even if just poly cross ... elbows start sending out early warning sos twinges. Mine happens around 6 hours ... whack ... go figure. Many post TE elbows are like Radar in MASH ... they know the injured are imminent.

#### McLovin

##### Legend
Good luck ... is PistolPete a Oklahoma State Cowboys reference?
Go Pokes! (my youngest daughter attends OSU).

#### ByeByePoly

##### G.O.A.T.
Go Pokes! (my youngest daughter attends OSU).
Obviously a brilliant young lady. Lucky for you she missed streaker night on the strip ... and rolling that Bonanza bull into Theta pond.

#### PistolPete23

##### Rookie
@PistolPete23 ... your best theory test subjects will be TE elbow degraded players. Not current TE ... everything hurts ... not never had TE ... nothing hurts. You need to test your theory with players where any poly, even if just poly cross ... elbows start sending out early warning sos twinges. Mine happens around 6 hours ... whack ... go figure. Many post TE elbows are like Radar in MASH ... they know the injured are imminent.
Very hard to test. You would need a variety of control groups, etc. A more recent study seems to suggest no correlation between fatigue-related injury and string type. https://www.researchgate.net/profile/Jihoon_Choi17/publication/288515796_Incidence_and_Prevalence_of_Musculoskeletal_Conditions_in_Collegiate_Tennis_Athletes/links/5681be5208ae1975838f9309/Incidence-and-Prevalence-of-Musculoskeletal-Conditions-in-Collegiate-Tennis-Athletes.pdf