I read enough of it to understand that you didn't summarize it. Are you seriously suggesting that you read the entire thing, understood it, and captured it with a paragraph that was only tangentially related to a small point made in the intro to the paper?
I'm just calling you on the bs man
No one's going to read all of that. Especially me, I'm from ASU, and looking at a medical school writing about physics in comparison to a business/science school:
I don't mean the wrist joint, I mean all bent joints in your body. These are places where two things can happen:
Energy can be stored.
Energy can be released.
Energy is usually "stored" for these shots like drop shots.
In this situation for serves, we are releasing energy for spin and power. The power then begins to bend more at certain joints and eventually releases on the racket by going through all major joints from legs to wrist.
Improper serve technique can put some of that energy back to you. Although torso's are enough to withhold certain car crashes, the arms, elbows are much weaker, and over years of wear and tear it degrades and causes injuries as we've seen many of.