You won't get a sore arm / shoulder with poly if...

[Radical Shot]

...you don't play with them after the strings are dead!

I think that the combination of long durability with poor tension holding characteristics of a poly cause people to use them long after they are actually dead and are giving nothing back to the frame or person.

It's at this stage that the poly becomes lifeless and boardy, causing the person to over-hit, over-extend and ultimately get a pain in the arm.

Fresh polyester is crisp, powerful and soft. Dead polyester is none of these.

Any other thoughts?

[Prince_of_Tennis]

All preference..I see people play with their luxilon strings for months and have no complaints of pain. I like the boardy feel! I hate fresh strings too much feel.