Is the back leg a main source of power on the serve?

[arteddie]

thank you jdawgg. you did a great summary. I would only add. If we all agree that the serve is a throwing motion upwards, then it should also be very cleaer that the weight is mostlly on the back leg uhtil initiation of the throw. look at any pitcher or quaterback.

 

[xFullCourtTenniSx]

First off there is a difference between where the power is from and where the weight is focused. The general pattern is front to back to front. Do you disagree with this? Or not?

Secondly in this picture where is Jeff's weight focused? Front leg or back leg? LOL.

First off, no there isn't. Power is defined as energy transferred over time. A bit of mathematical manipulation can be used to show that this is the same as the vector dot product of force (weight) and velocity. Ergo, greater source of force generation generally indicates greater source of power.

Secondly, watch the video and you will find out that the thumbnail comes from him showing what he believes is the incorrect way to load the legs, so your argument here is also dead.

It's kind of sad that scientific data can be posted, and the only valid criticism that was made was "who's Steve Johnson?"

You could question the method of measurement, the very questionable sample size of 1, but no. We go with "what I do FEELS different", "what he does LOOKS different", "what this (potentially incorrect/incompetent/clickbaiting but I ignore that because I like them for no good reason or because their views align with mine) YouTube coach says is different".

This is hilarious. You're telling me the forward swing of the racquet causes the leg drive?? For an experiment, bend your legs (don't move them, keep them there), swing your racquet forward like a regular serve where the racquet drops. Do you magically jump off the ground?

This is simple stuff guys. I see this Intuitive Tennis channel has infected many minds with his misconceptions. The leg drive is caused by... wait for it.... the legs pushing off the ground. Newtons third law, the ground exerts an equal and opposite force on your feet. Tell me how to jump without using your legs to push on the ground. Tell me how some explosive upper body movement magically levitates your body off the ground.

This is where, I imagine, all these misconceptions come from:

Intuitive says "There are other forces propelling the feet off the ground, it's not an active jump" ; "the body mechanics that are making us leave the ground have nothing to do with the legs"

Someone please explain to me the physics of this????? You can see his legs extend during his serving motion, how do they extend without forces from the quadricep femoris muscle group? It doesn't take someone with a degree in Mechanical Engineering and NTRP 5.0 to know this... just some common sense. TT forums should pay me to dispel all these misconceptions. Frankly, I'm really surprised at this whole thread.

This is where the whole issue between teaching how to execute versus what is actually happening comes in. A better sequence of muscle usage comes more naturally for most when they're told to reach for the ball (or something similar). A disconnected motion usually results for those told to jump for the ball, since they usually try to hit it volleyball style, where most, if not all, of the forces generated will be internal forces, and therefore inferior to one that properly uses ground reaction forces.

Humans didn't learn to walk or crawl because they knew they had to use friction forces, they just had a goal and did whatever they could to achieve it. Will knowing how it works make us better at it? Maybe. But you'd have to combine understanding and teaching on a level far beyond what we're at.

 

[arteddie]

First off, no there isn't. Power is defined as energy transferred over time. A bit of mathematical manipulation can be used to show that this is the same as the vector dot product of force (weight) and velocity. Ergo, greater source of force generation generally indicates greater source of power.

Secondly, watch the video and you will find out that the thumbnail comes from him showing what he believes is the incorrect way to load the legs, so your argument here is also dead.

It's kind of sad that scientific data can be posted, and the only valid criticism that was made was "who's Steve Johnson?"

You could question the method of measurement, the very questionable sample size of 1, but no. We go with "what I do FEELS different", "what he does LOOKS different", "what this (potentially incorrect/incompetent/clickbaiting but I ignore that because I like them for no good reason or because their views align with mine) YouTube coach says is different".



This is where the whole issue between teaching how to execute versus what is actually happening comes in. A better sequence of muscle usage comes more naturally for most when they're told to reach for the ball (or something similar). A disconnected motion usually results for those told to jump for the ball, since they usually try to hit it volleyball style, where most, if not all, of the forces generated will be internal forces, and therefore inferior to one that properly uses ground reaction forces.

Humans didn't learn to walk or crawl because they knew they had to use friction forces, they just had a goal and did whatever they could to achieve it. Will knowing how it works make us better at it? Maybe. But you'd have to combine understanding and teaching on a level far beyond what we're at.

Does "reach for the ball" do it? I think maybe if I am not going to leave the ground. But perhaps energetically "cartwheel" at the ball ALL IN ONE UPWARD EXPLOSION would work better. Then again, there also needs to be a feeling of a throwing motion, letting the hips and torso LEAD the arm, and the arm coming along, with lag, for the ride.

The diffiulty as I see it in teaching / executing a high level serve comes from having threee "axes of rotation": 1) Rotation of the torso around a vertical axis through the middle of body, 2) a cartwheel action through a hoizontal axis going through your back and belly button [or thereabouts], and 3) a "summersault" motion through an axis perpendical to the cartwheel. Others just call all this together a "twisting cartwheel." I guess you could probably develop a decent recreational level serve just by doing (1) but it would probably end up being a kind of flat or slice with a low margin of error.

The trickiest part is that these three rotations, as a resutl of leg and torso movements, have to all happen at once in one "launch" out of the loaded position / trophy position. Both legs need to push at more or less the same time, but bc of the cartwheel, the back foot begins milliseconds before and certainly leaves the ground first. The front foot hardly needs to leave the ground and the serve would look quite similar. At any rate, my 2 cents as someone who has been working on this regularly over the past 15 months or so.

 

[SystemicAnomaly]

@arteddie

Yikes... are you serious? Snake oily?

Have you heard of Jeff Salzenstein (Former top 100 ATP pro)? The dozens of other top 100 ATP and WTA athletes that have worked with Kovacs on their serve? He was literally head of the sports science program at USTA.

Salzenstein said he only learned this tip because of his continuing studies of the game. He also has a massive serve yet he didn't know until more recently. Further proof that you can be doing something and not even know it. He mentions here what I've been saying, that yes it is very possible to shift your hips and load your back leg. Most don't, however.

While the Intuitive Tennis guy is a good player, we also had a lot of high level players saying their power came from a wrist snap on the serve (which we know to not be true, it's from ISR which is a result of setting up earlier stages in the serve correctly). Intuitive Tennis claims that there is no leg drive on the serve -- that is just silly. Talk about snake oil...

Note that the Spring-Loaded pinpoint serve from Pat D, The Serve Doctor, uses a somewhat different weight distribution & mechanics than Jeff’s back leg-loaded serve.

With Pat’s retro Spring-loaded serve, the back foot is brought forward for the pinpoint with only a small portion of the body weight on it. A lions share of the weight is on the front foot. When the back foot is brought forward, only the tip of the foot (the toes) up here to be on the ground with not a whole lot of weight on it

While Pat D’s SL serve was not something that I used all the time I found that it could be quite effective when I did use it. I’m not saying that Jeff is completely wrong but there is more than one way to achieve results on the surve

 

[socallefty]

I’m somewhat new to analyzing strokes frame by frame as many of you do, but don’t most good servers get power from getting good knee bend on both legs? The timing of when they transfer their weight forward and the balance of back/front foot force pressing down on the ground to generate upward force would obviously depend on whether it is a platform or pinpoint stance serve. Can the same principles be used to discuss both platform and pinpoint serves in terms of sequence of weight transfer?

To me, the only universal takeaway seems to be that the deeper the knee bend, the more the ability to generate upward momentum and if you time it right, the faster the serve.

 

[FiddlerDog]

No, the speed of the racket is the source of the power on the serve

 

[jdawgg]

This is where the whole issue between teaching how to execute versus what is actually happening comes in. A better sequence of muscle usage comes more naturally for most when they're told to reach for the ball (or something similar). A disconnected motion usually results for those told to jump for the ball, since they usually try to hit it volleyball style, where most, if not all, of the forces generated will be internal forces, and therefore inferior to one that properly uses ground reaction forces.

Humans didn't learn to walk or crawl because they knew they had to use friction forces, they just had a goal and did whatever they could to achieve it. Will knowing how it works make us better at it? Maybe. But you'd have to combine understanding and teaching on a level far beyond what we're at.

I think the original question from OP was who was correct about the leg drive on the serve, Intuitive or Kovacs (basically which technique will get you the highest performance). My intent was to prove that Kovacs was correct about the leg drive, not teach people how to jump on their serve.

As far as the question:

Who teaches the serve better to players first learning how to leg drive -- Kovacs or Intuitive? Based on these two videos you can't really compare, it's a different subject entirely. Kovacs video didn't address how to first teach people the leg drive. Intuitive tennis video might be better for those players because a lot of NTRP 3.0-3.5 players mistime their leg drive rendering it useless. Better to just eliminate it. But what about the players who don't mistime their leg drive? Should we spoon feed everyone the same advice, "Don't jump on your serve! The complex body actions performed on a tennis serve will propel the feet off the ground passively." I wouldn't tell anyone that because it's obviously incorrect. Let alone blanketly applying it to everyone, I imagine some with proper mechanics will stop leg driving all together based on this advice and make their serve worse.

The better advice for those players would be: 1) get a good coach or 2) video your serve and check right when your legs are pushing off the ground, if your racquet isn't starting to drop at roughly the same time (like your racquet doesn't drop until your legs are extended) then either 1) stop jumping on your serve because its just complicating things and not accomplishing anything other than making your contact point slightly higher 2) follow a teaching progression to properly time your leg drive, will take weeks of coaching to change. In my experience as a tennis coach, most would opt for #2.

Then, if your leg drive is correct, move to a back leg loading progression that Kovacs teaches to learn how to more effectively generate power on your serve.

 

[Mungo]

My serve plateaued, or even declined, a few months ago when I noticed that my back leg liked to wander / slide around. I suppose my former stance was pinpoint, but with the back leg sloppy, rather than a very deliberate step up. It was bad enough that I was burning through shoes quickly with wear next to the big toe from dragging it on the court. In videos it looked a lot like a one legged serve, which I concluded was a problem, but which is a conclusion I am starting to at least partially revisit. So I switched to a platform stance with a lot more emphasis on stability and equal distribution of weight. Consequently, I have not found it easy to serve from inside the court. Perhaps worse, I think this is what has been inflaming my back leg groin and making me dial back my game the last two months. Going to try and re-develop a pinpoint stance now, without the rear leg sloppiness. I didn’t follow closely this entire thread, but there were a few nuggets and videos in here that I think were helpful in connecting these dots. Will come back and update this post if my hunch is successful.

Update: it is hard to just change stances, however I hit a few baskets and can confirm that pinpoint stance eliminates the stress I was putting on my back leg groin. I think this ties into this thread because, at least for this low level recreational player, attempting to harness the back leg in a platform stance led me down a very bad path!

 

[arteddie]

My serve plateaued, or even declined, a few months ago when I noticed that my back leg liked to wander / slide around. I suppose my former stance was pinpoint, but with the back leg sloppy, rather than a very deliberate step up. It was bad enough that I was burning through shoes quickly with wear next to the big toe from dragging it on the court. In videos it looked a lot like a one legged serve, which I concluded was a problem, but which is a conclusion I am starting to at least partially revisit. So I switched to a platform stance with a lot more emphasis on stability and equal distribution of weight. Consequently, I have not found it easy to serve from inside the court. Perhaps worse, I think this is what has been inflaming my back leg groin and making me dial back my game the last two months. Going to try and re-develop a pinpoint stance now, without the rear leg sloppiness. I didn’t follow closely this entire thread, but there were a few nuggets and videos in here that I think were helpful in connecting these dots. Will come back and update this post if my hunch is successful.

Update: it is hard to just change stances, however I hit a few baskets and can confirm that pinpoint stance eliminates the stress I was putting on my back leg groin. I think this ties into this thread because, at least for this low level recreational player, attempting to harness the back leg in a platform stance led me down a very bad path!

See perhaps Rick Macci's videos on the serve leg drive. He has a way of breaking it down with simple progressions. It becomes simple once you have been able to find an exercise that isolates the right feeling. Pin point or platform will not matter then as much, beyond what your personal preference is.

 

[J_Sneed]

One thing I don't understand is that, if Kovacs is right, wouldn't pinpoint stances be completely suboptimal? Like, to the point that almost no top pros would use them, because they would eliminate the main source of serve power? Instead we see huge servers like Ivanisevic and Isner who appear to put virtually no weight on their back leg after coming out of the initial rocking phase of the serve (it's even more dramatic with Isner, as he actually steps forward onto his front foot as he tosses).

I'm aware there's a bit of an eye-test vs. science thing here, but it frankly seems impossible that either of them could be loading on, or driving from, their back foot here, as they remain on the toes of their back feet throughout the whole forward phase of the swing, which would suggest the weight is on the front foot.

 

[ballmachineguy]

One thing I don't understand is that, if Kovacs is right, wouldn't pinpoint stances be completely suboptimal? Like, to the point that almost no top pros would use them, because they would eliminate the main source of serve power? Instead we see huge servers like Ivanisevic and Isner who appear to put virtually no weight on their back leg after coming out of the initial rocking phase of the serve (it's even more dramatic with Isner, as he actually steps forward onto his front foot as he tosses).

I'm aware there's a bit of an eye-test vs. science thing here, but it frankly seems impossible that either of them could be loading on, or driving from, their back foot here, as they remain on the toes of their back feet throughout the whole forward phase of the swing, which would suggest the weight is on the front foot.

Next time you are at the court, or if you have room for shadow swings in the house, try one-footed swings. Try all front foot then all back. All front foot allows the muscles on the hitting side to relax, elongate and swing fast. All back foot and you are all contracted on that side and…good luck.