That's because there are that many out of shape and lame morons who wants to pretend to be Fed but find a real sport too hard so they'd rather make up a fake-mini version of it which is easy and doesn't require any running.
If they get enough lazy morons together they can even pretend it's a...
That's pretty much the definition of being confused.
"an argument is sound if it is both valid in form and its premises are true"
This is just plain wrong
I dare anyone to cue something verbally over teh interwebz to ten people they dont know and haven't talked to and get a...
Since Im the one responsible for this thread-drift I'll get @Digital Atheist @Chas Tennis and @Dragy in here as well.
In @yossarian 's example above I think we all agree that the instructor wouldnt talk like that. But a (hopefully) probable version would be:
Take your average tennis player...
Of course! The answer is yes.
True, but also on a heap of other variables. A BIG heap of other variables.
I think you are overly fascinated with muscle-length. (see, for example, the summary of this article https://journals.physiology.org/doi/full/10.1152/jappl.1918.104.22.1685)
Since Ive already posted on this above (https://tt.tennis-warehouse.com/index.php?threads/does-have-a-john-mcenroe-like-service-motion-put-more-or-less-strain-on-the-body.684015/post-14804476) I might as well add some more.
What he does with his shoulder eg. externally rotating it before...
Hmm... The good thing about the JMac serve is that it requires little flexion/extension of the back and practically no "rotation" (I am assuming you mean twisting? aka rotating the shoulders one way and the hip the other? since everyone can rotate their spine by spinning 360 degrees)