Serve toss question....

[gzhpcu]

I would advise to speak to Brian Gordon.
I do NOT know however how to get in touch with him?
E-mail? John may help

A simple Google found his email address. I'll tell him to look at this thread...

[gzhpcu]

Ooops...he changed his email address....

[uspta146749877]

3 ways to climb a mountain

Ooops...he changed his email address....

There are to ways to contact him-
1.leave a personal message at this forum
2.leave a persona message at the tennis-warehouse forum
3.ask John Y to help

[uspta146749877]

B G

You may go

http://bgordon.usptapro.com/Default.aspx?AspxAutoDetectCookieSupport=1

click Contact me
and leave a message overthere

[tennis_chiro]

4 feet is almost 10% of your "action distance"

Phil,
just be careful if you decide to try out Soderling's service motion, maybe have an ambulance on the side of the court.

That slow motion above of his serve is really fascinating. He has TREMENDOUS leg drive, but I'm not sure it is doing much for him except getting him a little further up in the air to meet the ball. Certainly, he generates a lot of energy, but with such a limited hip turn, I wonder how much of that energy actually gets translated into racket head speed towards the target.

Soderling definitely has a good serve, but he may be leaving a lot on the table. Someone 6' 5" has a reach with the racket at least 8" more than the average six-footer, and that's before the jump. Imagine serving with the net about 4" lower. That would significantly effect your "acceptance window".

I, for one, was a little surprised when I did my little math problem earlier in the thread that the contact point was that far forward. But I think the facts stand. Now realize that the ball travels about 80 feet to the returner and for the forward toss it is about 4 feet less. Now imagine that the receiver has to take the ball 4 feet earlier. By tossing that ball into the court, the server is taking that 4 feet away from the receiver. Soderling is probably forfeiting about 3 feet of that potential advantage. That's like making the 125 mph serve into 131 mph.

As far as Soderling going forward more, he just doesn't have the agility and mobility to serve and volley on any kind of a frequent basis. He can finish up front, but he doesn't want to have to defend a pass on anything less than an overwhelming approach. That may be one reason he stays so far back: he would be slow in recovering back behind the baseline. You can point to serve and volleyers like Isner and Karlovic, but as slow as they may be, they learned to serve and volley when they were young. It's a very tough rhythm to learn after you are 17. (And it took Karlovic till about 28 to learn it!)

Quote:
Originally Posted by gzhpcu
Is only going up on the hit really important? Does going forward have only a minor influence on the speed of the ball? Do I really only toss well forward if I am going to the net?
Brian and John are best experts to ask.

John and Brian have already answered most of these questions in their articles and I think they might refer us there, but I wouldn't mind hearing some clarification on those points.

But most of all, Phil, as a chiropractor, I have to recommend against you trying Soderling's motion.

don

"Action distance"
I'm making up a new term. In the post above, I said you cut off about 3 feet off 80 feet the opponent has to react to the ball, but in actuality, the opponent can't make any move until the reaction time has expired. That turns out to be 150 to 300 milliseconds. We'll call it 2/10 of a second. On a 125 mph serve, that is (125mph x (88fps/60mph) x .2 seconds) = 36' 8". So the actual distance the ball travels while the receiver is moving to make the return is just a little over 40 feet. I'm going to call this distance the "action distance". And the time for the ball to travel the action distance the "action time". And if you take another 3 feet away from the receiver by leaning into the court to make contact, you are cutting the "action distance" down by 3'/42' = 7.14% (relative to Soderling). So the effective speed of the 130mph serve for someone who throws the ball 4 feet out in front of the baseline is about 130 x 1.0714 = 139.2mph compared to the person who serves like Soderling and meets the ball about 1 foot inside the baseline. Just imagine someone having to take the big first serve 3 feet earlier, or having to move in 3' to return first serves. This effect would be enhanced by the fact that the ball has been subject to 3 feet less of wind resistance. I really wonder what the numbers are for Isner and Battistone. (Can't get the image out of my mind of Isner using Battistone's motion.) And I'm pretty sure Roddick is in there pretty far as well. Sampras certainly was.

This point of view also adds more value to the leg drive even if the big upward move doesn't get you much actual raw speed (I don't think it's as much as most people seem to think), it makes getting up to that forward contact point a little easier. If it's worth 10 mph on position and just 5 mph on actual ball speed, now we are talking about a significant difference.

I haven't seen this argument put out there before. I still think the kids need to learn to be able to serve consistently standing still and balanced before they start trying these contortions, but I am beginning to see more benefits to getting all that leg drive to get into the court. (But not from the actual increase in ball speed that most people ascribe to it. I think that is only a few miles per hour at best.)

I'd like to hear what the rest of you think.

don
PS I got my old handle, tennis_chiro back!

[John Yandell]

Don,
Jamming on Dec issue so didn't read line for line, but did you figure the deceleration factor. 120mph is 90mph before the bounce, 60ishmph after the bounce 50-55ishmph at contact.

john

[gzhpcu]

Howard Brody says that for a 120mph serve (which slows down to 55mph at impact), reaction time is 0.59 sec.

If you are 5' inside, for a 110 mph serve, reaction time is also 0.59 sec.

[uspta146749877]

Source for a quote

Howard Brody says that for a 120mph serve (which slows down to 55mph at impact), reaction time is 0.59 sec.

If you are 5' inside, for a 110 mph serve, reaction time is also 0.59 sec.

Could you let me know a source/book/article for this quote?

[tennis_chiro]

How to get a headache thinking about the toss

Howard Brody says that for a 120mph serve (which slows down to 55mph at impact), reaction time is 0.59 sec.

If you are 5' inside, for a 110 mph serve, reaction time is also 0.59 sec.

According to Brody, the reaction time is .59 seconds at the baseline for a 120 mph serve. I would not call that reaction time; I would call that the time the player has to react to and move to and hit the return. Reflex reaction time is much less than .59 seconds. But let's see:

Assume the ball starts out at 120 and drops to 90 when it meets the court. It leaves the court at 60 and slows to 55 at impact. (Remember air resistance goes up with the square of the velocity so the ball slows down much more when it is going fast because the air resistance is much greater). Also, we are generalizing here. The ball does not travel in a true straight line. It also doesn't slow down uniformly under the influence of drag and wind resistance. But close enough for purposes of this discussion.

And let's assume we are using the numbers I generated in post#5 for Hoad and also for someone of Hoad's height not reaching into the court

So:

The first 60 feet the ball averages (120 + 90)/2 = 105 mph.

Not Reaching Into the Court
This guy has a reach of 10 feet straight up
Actually 60 feet is the ground distance to the service line from the baseline, but assuming this is a serve on the T (shortest distance), the actual distance is greater than that. Assuming the server tosses straight up, the distance = square root of ((reach up squared + 60 squared) = SqRt(100+3600)= approx. 60ft 10in.

So if the serve lands 10 inches infront of the service line, 60 feet is right. If the return is met 10 inches in front of the baseline at about 3 feet. It travels another (Square root (3 squared + 18 squared) = SqRt (9+ 324) = 18 ft 3 inches.

So the ball travels 60 feet at 105mph average plus 18 feet 3 inches at 57.5 mph average.

Therefore our travel time for the ball from racket to racket is:

60 feet divided by (105mph x [88fps/60mph]) plus 18.25 feet divided by (57.5mph x [88fps/60mph]) =

60/(105x88/60)sec plus 18.25/(57.5 x 88/60) = (3600/9240) + (1095/5060) = .390 + .216 = .606 seconds. Obviously, if the server was leaning into the court, the time would be lower.

This is looking like a longer project than I want to undertake right now, ... but clearly .59 seconds is not the reaction time. It is the time that the serve travels in the air to a return at the service line. Furthermore, if average reflex reaction time is 150 to 300 milliseconds, and we call it .2seconds, the receiver must make his move in about .4 seconds. If you contact the serve 4 feet infront of the baseline, you are taking 4 feet off the time the ball is in the air before the bounce (when it is moving faster), so the reduced time is really only (4)/(105 x 88/60) sec = 240/9240 sec = about 26 milliseconds. But that reduces the time the receiver has to move by 1/16th or about 6%. Because of the increased air resistance and loss of speed after the bounce, the velocity of the serve would have to be (for argument's sake) at least 8% faster to achieve the same effect with a serve hit at the baseline(kind of like Soderling). You could look at it from the point of view that Soderling's serves would seem 10 or more mph faster if he got the ball out in front a little more, or you could say his 130 mph serves only seem like 120 mph to the players he is playing because he doesn't reach into the court.

It would take me a full afternoon to work out the spreadsheet so you could just plug in the parameters and get the time from serve to return. But I think the math is straightforward, there is more of a benefit to reaching into the court than we have generally been giving it credit for.

I'm going to stop before I get a headache. I know I've already given some of you one.

don

[gzhpcu]

Could you let me know a source/book/article for this quote?

"The Physics and Technology of Tennis" , Howard Brody, Rod Cross, Crawford Lindsey,2002, Chapter 21 "Receiving Serve", page 210

[gzhpcu]

Howard Brody says that for a 120mph serve (which slows down to 55mph at impact), reaction time is 0.59 sec.

If you are 5' inside, for a 110 mph serve, reaction time is also 0.59 sec.

I should have mentioned, that this is what he calls reaction time if you are standing on the baseline. He says "If you move 5' inside the baseline you have transformed your opponent's serve into a 120 mph blast, when you consider the time you have to respond" he goes on to say that "moving five feet behind the baseline gives you 10% more time to react and get to the ball".

[gzhpcu]

According to Brody, the reaction time is .59 seconds at the baseline for a 120 mph serve. I would not call that reaction time; I would call that the time the player has to react to and move to and hit the return. Reflex reaction time is much less than .59 seconds. But let's see:

Don't quite follow your reasoning... The ball leaves the racket and, if the player is at the baseline, the ball reaches him .59 seconds later. Clearly, perception has to be rapidly translated into reaction, the body has a certain inertia, etc., but why is this not reaction time?

[uspta146749877]

Don,mercy

Please put more blank lines into your posts

[tennis_chiro]

Reaction Time...Reflex Time..."Action Time"

Don't quite follow your reasoning... The ball leaves the racket and, if the player is at the baseline, the ball reaches him .59 seconds later. Clearly, perception has to be rapidly translated into reaction, the body has a certain inertia, etc., but why is this not reaction time?

Whether you are a prime-of-life 18 year old or a healthy 60 year old, the basic reflex reaction time will be somewhere around 2/10ths of a second. That is, if you handed a healthy 60 year old a "reaction button" to identify Fh or Bh return after a serve is hit to him, he could be competitive with the 18 year old (within probably 5 hundreths of a second...just guessing: there certainly is some degradation with age which could reasonably add 25% to the 150 to 300 milliseconds average reflex reaction time[wikipedia]). But ask that person to try to compete with the 18 year old in moving their body into position and making the appropriate swing to return a 125 mph serve and they are going to be seriously overmatched.

For example, take a currently 58 year old Jimmy Connors and ask him to do a reaction drill with little physical demands (like pressing a button), and he would probably still beat most 18 year olds. He was just "wired" better than most of us and I would bet his reflex reaction time when he was 22 was closer to 100 milliseconds or at least at the bottom of the 150 to 300 millisecond range. Even if that reflex reaction time has increased over time for him, he is probably still pretty good. But if you ask him to move and make a return like he used to, he is going to need more "action time" than he used to need to get to the ball and make his stroke. Although I imagine if he only has to take one step, he can still return a 125 mph serve, but not the 135 or 140.

I am not disputing what Brody is saying. The math says hit the ball from 5 feet closer and you decrease the time it takes for the ball to get to the receiver by the equivalent of about 10 mph. So, for a ball leaving the server's racket at the same speed, but 4 feet closer to the receiver, that serve is effectively about 8 mph faster than the serve struck like Soderling's from directly over the baseline. (Imagine Nolan Ryan pitching from 57' instead of 60'. In fact, I wonder if some of the oversize hurler's of today are releasing the ball at least a foot closer to the plate than the average pitcher of the past. I don't know the angles there.)

But what I am trying to say is that the 4 feet you are taking away from your opponent is actually more of a burden on him than the simple proportionality of 4 feet:80 feet::reduced reaction time:total original reaction time.

At the top end of the game, everyone is relatively quick. There are no more poor athletes out there. Even Ivo Karlovic is probably pretty quick relative to the average person, and when it comes to just pushing a button, he might even be quick for an ATP pro. Remember, he still hits some pretty good returns when he doesn't have to take a step. But ask Ivo to move to the ball and use the time after his "reflex reaction" has told him to hit a Fh or Bh return, and he looks like a 4.5 or 4.0 player moving to the ball, albeit a pretty scary one. He needs all of that .4 seconds after the .2 seconds his reflex reaction took to get him started to move that 6'10" structure into position to execute his return. And if you take 26 milliseconds (see my calculation in the earlier post #39)) off the 400 he has to execute the command his brain has given his body, it is a greater performance burden on him than taking 26 milliseconds off a 590 millisecond "Brody reaction time" would seem to indicate.

Furthermore, it should be noted that moving back 5 feet is going to be of more benefit than a proportional 5 foot increase in the distance the serve travels would seem to indicate. That 5 feet is coming after the ball has bounced and after the ball has already slowed to 55mph and the average speed that last 5 feet will be well below 55mph whereas I ascribed an average speed of 105mph to the distance lost before the bounce by meeting the ball leaning well into the court.

In the past there was a significant penalty for that: more time for your opponent to get to the net, but now that penalty is almost nonexistent. If you can hit the ball deep in the court, you only sacrifice a little time as the ball travels the extra distance to your opponent at its higher speed prior to the bounce. (All the more reason to hit deep.)

Also, it is of major significance that when you move back to hit the return, the ball will be traveling much slower when you meet it. It's much harder to hit a fast moving ball regardless of how much time you have to set up for it.

Okay, that should be more than enough for right now. (I got rained out today. And probably for the next 5 days as well!)

BTW, no one has said anything about my vision of John Isner executing Brian Battistone's service motion. Of course, his knees would probably be more injury prone than Yao Ming's left foot, but if I had a kid that was young enough and it was clear he was going to be over 6'7"...although you know they changed the rules for Pancho Gonzales in protennis one year...they made him serve from 3 feet behind the baseline, and he already had to keep one foot on the ground...how great was that serve?! I'm just sayin'

don

[uspta146749877]

No opinions,please

It is a matter of opinion how legal
is a serve of Brian Battistone.
He is allowed to play challengers so it has to be legal.
it is better to be rained out than have a snow storm