Slow motion and stop action video of Serena Williams hitting a slice serve ace while winning the title against Marion Bartoli at the Bank of the West Classic tournament, Stanford, CA 2011. Original video and content by Jim Fawcette (c)jfawcette
Update: Oct 25, 2016
Since this video I did of Serena way back in 2011 is still getting traction, let me update some things I've come across for those that are as interested in pro technique as I am.
First, I am still amazed by the emotional response of what I call the "Pronation Police", who treat the term as if it is a religious totem. But if the issue is actually trying to understand pro technique rather than fight over semantics, there are many, good resources. I'm simply an enthusiastic fan that follows the experts. I suspect part of the problem is that well-meaning tennis instructors in the 90s in correctly trying to describe how pros' arms rotate, mistakenly used a technical term in pronation to simply mean arm rotation and in the process bowdlerized it. Now, some attack anyone that questions their misuse. Sigh.
One commenter here noted that on the transition from leading with the racket edge to facing the ball, the arm appears to go through some pronation. That made sense to me. However, what I read is that this is "Mistakenly attributed to pronation when it is caused by interior shoulder rotation." Secondly, if you look closely at how on follow through, the wrist of top pros is often canted , not in alignment with the forearm, and the inside, forearm bone is thrust downward, that suggests "ulnar flexion" or "ulnar deviation", which is a different type of forearm rotation, one contradicting pronation. Finally, pronation is, technically, independent motion of the forearm, not part of "long axis rotation". Whew
Check out these tight shots of Djokovic and Raonic I took from their final at Indian Wells this March, paying particular attention to their wrists:
flic.kr/p/HHjMgr
flic.kr/p/ESL7DH
Here are what actual sports science researchers say. As two PhDs in biomechanics have written, Dr. Mark Kovacs of the ATP, who is featured on Fuzzy Yellow Balls, and Dr. Brian Gordon of Stanford, who is featured on www.tennisplayer.net "Pronation has a minor role in professional tennis serves" and "What tennis instructors incorrectly call pronation is actually ULNAR DEVIATION", as well as "Pronation contributes at most 10% to serves". Check out the extensive 3D modeling of professional serves on Tennisplayer dot net (Paid site, sorry):
www.tennisplayer.net/members/...
Here is an exchange Dr. Kovacs had with Will Hamilton of FYB:
Kovacs: "Our research shows that pronation has little or no role in the pro serve."
Will: "Wow. We were taught that way it the 90s".
Kovacs: "Yes. But they were wrong."
Link (sorry, but it is paid):
www.fybcourses.com/products/th...
As John Yandell writes in an excellent series there: "In addition we'll try to understand the difference between the common usage of a term like “pronation” in coaching and it's much stricter biomechanical definition-and how actual pronation is or isn't really involved in the pro serve motion. .. is there any independent pronation in this technical sense? According to Brian, the answer is usually no. And this seems to be consistent with what we see in the Federer high speed video. If you watch the upper arm and forearm it is impossible to detect any significant independent movement from the elbow out. The upper arm, forearm, hand and racket all seem to rotate as a single unit."
That's not pronation.
Meanwhile, for the Pronation Police, let me offer this Internet meme:
"You keep using that word, I do not think it means what you think it means”
-- American actor Mandy Patinkin, who portrayed the swordsman Inigo Montoya in the 1987 romantic comedy The Princess Bride • You keep using that word.
23 окт 2011
