Young kid at the club, using poly, restringing every 4-6 months

Discussion in 'Strings' started by roman40, Jun 8, 2013.

  1. gameboy

    gameboy Hall of Fame

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    You are correct. Using people who hit hundreds of shots per session getting more injuries compared to people who hit tens of thousands of hits per session is ridiculous.
     
    #51
  2. roman40

    roman40 Rookie

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    Interesting, so it looks like quite a few folks don't think playing with poly string for a long time is an injury risk. I guess poly strings are a fairly recent phenomenon, and composition/characteristics of today's strings is quite different from 10 years ago, so it's not surprising that we don't have any comprehensive studies on this.
     
    #52
  3. roman40

    roman40 Rookie

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    Don't confuse stiffness and tension, completely different characteristics. Polys do become more stiff (or lose elasticity) with time, just like any other string, but much faster than multi/gut. Elasticity in the string is what absorbs the energy from the ball. I'd like to see a 3d graph of tension/stiffness/energy absorption. My guess is that stiffness becomes a more dominant factor than tension, as tension drops. But, I'd like experts to chime on that.
     
    #53
  4. Lukhas

    Lukhas Legend

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    Using people who care of their bodies and equipment many, many times more than any club hacker is indeed ridiculous. That's like asking why pro runners don't get as many cramps as amateurs or run faster, or why F1 pilots are better drivers and can sustain more dramatic conditions like extreme G force or low hydration than mere occasional karting enthusiasts.
     
    Last edited: Jun 13, 2013
    #54
  5. gameboy

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    This would not be very difficult to prove.

    Just chart the number of days played per year by the top 100 players over the last 20 years or so. If polys did cause more injuries, you would see the number of days play go down as more players switched to poly.

    It would not be conclusive, because there maybe other factors. But it would be a big clue. Lacking such evidence, there is absolutely nothing objectively backs the belief that polys cause injuries.
     
    #55
  6. gameboy

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    Yes, because we all know pros never get injured.
     
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  7. Lukhas

    Lukhas Legend

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    They do. Which means it's also not risk-free for them. So? What was your point? They get less injured because they take more care about their equipment and bodies, but they still do.
     
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  8. gameboy

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    The point is that there is absolutely no data to show that pros are getting injured more often since they started using polys. You have no facts to back up your wild claims.
     
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  9. Lukhas

    Lukhas Legend

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    My point was that it was moot to compare pros because the care they put on their equipment and body is far superior to mere club hackers.
     
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  10. roman40

    roman40 Rookie

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    But pros don't use poly strings for more than a few hours, often less than 1hr in a tournament, so data for the pros is irrelevant, we're talking specifically about playing with poly strings for an extended period of time.
     
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  11. gameboy

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    But at that point how do you know that hackers are getting injured more often than before? Perhaps they are getting injured at the same rate without the poly, but you are just noticing it more.

    This would be a classic confirmation bias case.
     
    Last edited: Jun 13, 2013
    #61
  12. julianashaway

    julianashaway Rookie

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    If you take a look at the TW string finder, the measurement of stiffness (also called dynamic stiffness) is used to rank strings for both power and arm friendliness. This measurement tells you how well a string will stretch and return to its natural state. This measurement tells you how much energy the string will return to the ball on impact (power). The more power comes from the string the less has to come from your arm (arm friendliness).

    There is no guarantee that stiffer strings will cause injury. It does make sense, however, that the more work the strings do and the less work your arm does the better chance you have to avoid injury.

    Compare how your arm feels after playing 10 hours with a full bed of poly vs 10 hours with a full bed of natural gut. Most would acknowledge that their arm feels better after playing with the gut. If it looks like a duck!
     
    #62
  13. gameboy

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    Where do you get the info that pros don't use polys in practice? Every Nadal practice video I see, he is using the black poly.
     
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  14. Lukhas

    Lukhas Legend

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    Nadal changes strings at almost every changeover, and brings many racquets in for practice. All at 55lbs.
     
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  15. gameboy

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    And again, go read the TW professors report on poly.

    Polys lose tensions ALOT. They do NOT get stiffer. If anything, constantly hitting fresh poly will put MORE stress on your body.

    This is why it is foolish to rely on anecdotes. Most people around here (INCLUDING ME!!!) thought polys got stiffer as you used it (that dead feeling). However, actual scientific study done by TW Prof showed clearly that is not the case.
     
    Last edited: Jun 13, 2013
    #65
  16. julianashaway

    julianashaway Rookie

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    True. When the string bed loses tension it will become a little more arm friendly. However, the stiffness of the poly has not changed. It was stiff to begin with and has not become less stiff. You would be better off (it terms of your arm) if you started with something less stiff than poly.
     
    #66
  17. roman40

    roman40 Rookie

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    Again, you're confusing tension and stiffness, which are not the same thing. Decrease in tension, with decrease in elasticity, doesn't mean the string is easier on the arm.
     
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  18. gameboy

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    No I am not. I only brought it up because of the claim that fresh string job is the reason for pros not getting injured more often.

    You are still wrong about polys losing elasticity. Again, for the third time, go read the TW Prof's report. The claim that the deadened feeling is due to the elasticity lose was disproved in the tests.

    Here is the relevant quote:

    "In a sense, it would appear that the string actually gets better with use, but you have to re-tension it to get the benefit....

    As the number of impacts increases, a polyester string loses tension. As tension decreases, both stringbed stiffness and string energy return decrease."
     
    Last edited: Jun 13, 2013
    #68
  19. SFrazeur

    SFrazeur Legend

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    Regardless of what terminology you wish to use the fact remains through empirical evidence (its happened to me) that old poly string hurts the arm.
     
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  20. Lukhas

    Lukhas Legend

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    It denies the fact that the dead FEELING comes from elasticity loss. Not that the string doesn't become less elastic with time.
     
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  21. roman40

    roman40 Rookie

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    Which article are you reading, because I don't think any of the articles on TW came to this conclusion.

    Can you post an excerpt from the article that indicates there is no elasticity loss. Thanks.
     
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  22. gameboy

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    So, you are basically saying, we should believe polys cause injuries, because you said so.

    Hmmm... as tempting as that is, I will pass on that.
     
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  23. gameboy

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    Then, you didn't read the entire report.

    http://twu.tennis-warehouse.com/learning_center/deadstringsPart2.php

    String is never in the same internal state from one impact to the next. It is never in the same state from one second to the next. For that reason, the performance of the string depends on its previous history. It is in a constant state of transition from where it has been. In a strung racquet, this internal state manifests as stress relaxation — i.e., tension loss. And the loss of tension results in more stretching which, by its nature, involves more energy loss due to more internal friction. This could be considered an "internal degradation" of resilience. But it begins as soon as you string the racquet and with every hit. Instead, it is really just the nature of string. The inherent structure has not been compromised, only its current state. If you retension that same string, it performs "better" than before. That is because the internal structure has actually been "improved."
     
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  24. SFrazeur

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    I am a scientific reason based person. However, I do not need to see scans or laboratory models to know that smashing my thumb with a hammer hurts. You can test and debate what actually happens when string goes "dead" or whatever term you wish to use. The fact remains that at some point dead poly will hurt your arm.

    I am willing to concede that there are probably, through random chance alone, people that dead poly will not hurt.

    I used to be one who thought it didn't matter. That it would't bother me physically. I have been proven wrong. Find out for yourself. Use a poly and only restring if it breaks. Then tell me how that goes.

    -SF
     
    #74
  25. newpball

    newpball Legend

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    As I said before some people can only find out things the hard way.

    People like gameboy may never become convinced, even if they get arm problems themselves: "my arm problems are not string related".
     
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  26. julian

    julian Hall of Fame

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    Chrome

    I have put a post for you about chrome at tennisplayer.net
     
    Last edited: Jun 13, 2013
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  27. gameboy

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    And some people still believe that the world is flat, even after you show them the picture of the earth.

    Look perhaps polys cause injuries in some other way. But to keep saying that old polys cause more injuries does not pass the smell test based on actual scientific study on this.

    P.S. I play with a full stringbed of poly until it breaks. I do have some shoulder issues, but I got that when I was playing with a full bed of gut. My shoulder has gotten better since then, even when using a full bed of poly.
     
    #77
  28. Lukhas

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    I like inverted commas: they usually mean you have to take what's between them with attention and not literally. Because literally it means "pre-stretching (tensing and re-tensing strings) does not make the string stiffer", which is wrong, as the article says. "Nice".
    Therefore, the elbow says "yes it's stiffer" and your head says "no it isn't". One of the few case I'd rather trust my elbow than my head. After all, my head's not the one suffering.

    EDIT: Basically, even if the way I use words or describe the phenomenon is wrong, I safely believe "old poly hurts". Or "high tension hurts". Or "co-poly hurts". As I wrote earlier in this thread, I'm pretty sure many players are fine using old co-poly at high tension until it breaks. doesn't mean we should do it. Or that the string is fine doing so, since it loses so much tension that a restringing may be better than sticking with it. Because to compensate for the huge tension loss, you have to produce more effort to compensate for it, which increases stress on limbs, libs that don't like the rigid strings either. Also, "bad technique also hurts".
     
    Last edited: Jun 13, 2013
    #78
  29. gameboy

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    Yes, that would be the correct approach if things like facts and scientific proof, don't matter to you.
     
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  30. newpball

    newpball Legend

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    Why am I not surprised? :|
     
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  31. gameboy

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    I didn't until I read this report.
     
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  32. Lukhas

    Lukhas Legend

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    If poly hurts my elbow even if my head says "it's fine", I prefer putting down the poly. It may not matter to me, but my arm doesn't say so.
     
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  33. roman40

    roman40 Rookie

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    It would be nice for TW experts to chime in, because I think you're misinterpreting the results. However, I find the article somewhat confusing as well. While clearly the stiffness of the string bed increases, they argue that elasticity doesn't change. Then what accounts for increased stiffness?

    "Figure 7 shows essentially the same thing with regard to energy return vs stiffness. The string gets stiffer with each re-tensioning to 10 kg and the energy return is typically higher for the stiffer pull numbers. "

    The string is stiffer at the same tension. "Better" in your excerpt, means better energy return, less tension loss, after re-tensioning. Performance in this article doesn't take comfort into account, only power/control characteristics.

    They also indicate increase in friction due to string wear (exaggerated in real life by dirt that collects on strings). This will also impact how harsh poly string feels.
     
    Last edited: Jun 13, 2013
    #83

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