Power Comes From The Ground

user92626 said:
:) stay balanced is not the same as push off the ground for power, which's been your argument I think.

But again, I agree with you about using legs to push against the ground.

Guys with injured knees, legs should be able to tell you how much power is missing when your legs can't push off the ground.

@10sbeast888 @ballmachineguy how do you suppose Djokovic gets off the ground or his leg goes from more bendy to less bendy in the forward swing? What for?


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Slow mo for identifying balance and ground forces is deceptive and real time is better imo. Watch him hitting live here, from multiple angles.

That is a great video to see how he doesn't excessively load into his legs and he is crushing these (not saying he doesn't load).

@Chas Tennis posted an older video of a senior playing changing from a "linear" stroke to a rotational modern forehand, but the leg loading on the right knee was excessive and ridiculous imo (especially for a player with a knee issue, this might screw the other one in short order and then he has two bad knees).

It seems like the coach is recommending he hit almost all forehands like that. I couldn't see that player lasting long with such a technique at his age. Compare that to joker and make up your own mind.
 
Digital Atheist said:
Slow mo for identifying balance and ground forces is deceptive and real time is better imo. Watch him hitting live here, from multiple angles.

That is a great video to see how he doesn't excessively load into his legs and he is crushing these (not saying he doesn't load).

@Chas Tennis posted an older video of a senior playing changing from a "linear" stroke to a rotational modern forehand, but the leg loading on the right knee was excessive and ridiculous imo (especially for a player with a knee issue, this might screw the other one in short order and then he has two bad knees).

It seems like the coach is recommending he hit almost all forehands like that. I couldn't see that player lasting long with such a technique at his age. Compare that to joker and make up your own mind.
Click to expand...
Senior player? That dude is like 37-40 lol
 
Digital Atheist said:
Slow mo for identifying balance and ground forces is deceptive and real time is better imo. Watch him hitting live here, from multiple angles.
That is a great video to see how he doesn't excessively load into his legs and he is crushing these (not saying he doesn't load).
Click to expand...
Most of his smoothness and clean hitting comes from his very early prep and unit turn as stressed countless times by @ProStaffFanatic. @Rosstour
 
Early prep/unit turn. I think we really need to exaggerate to get this sh1t right. ‘As if we’re preparing to hit a volley’. This should be our motto, folks. It will feel weird at first. Why should I prepare that fast? Let’s wait for the ball to come closer. Oops jammed!
 
user92626 said:
oohh i could get used to this. Being told I'm right every time! :laughing: :laughing:

(ok i'm done posting today. going back to my corner now. :giggle:)
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well VP - I just realized something.

the right sequence does matter... in terms of tennis longevity.

this is a very bad combination - pushing the ground to start a swing + loading leak.

this puts tremendous stress on your lower body joints in a very leaky stroke, which does not produce power efficiently... but the bigger problem is more INJURY RISK.
 
Digital Atheist said:
Slow mo for identifying balance and ground forces is deceptive and real time is better imo.
Click to expand...
Totally agree.

Sometimes watching at a few diff speeds (including real time) is instructive as well. Scrubbing back and forth, if you have the option, sometimes adds insight to weight dynamics as well.
 
10sbeast888 said:
well VP - I just realized something.

the right sequence does matter... in terms of tennis longevity.

this is a very bad combination - pushing the ground to start a swing + loading leak.

this puts tremendous stress on your lower body joints in a very leaky stroke, which does not produce power efficiently... but the bigger problem is more INJURY RISK.
Click to expand...
I will discuss the contents of your post when time allows.
Busy now.

But I must say I like this style of posting from you. :)
 
Digital Atheist said:
.. an older video of a senior player changing from a "linear" stroke to a rotational modern forehand, but the leg loading on the right knee was excessive and ridiculous imo
Click to expand...
Totally agree on this too. That was way too extreme, to the point of being a different biomechanic, imo.
 
Thanks for posting this vid. That real time side view of Djoko hitting rally groundstrokes is so great re seeing his forward leaning balance, and re watching what he does with his weight and balance out of the split step landings.
Digital Atheist said:

That is a great video to see how he doesn't excessively load into his legs and he is crushing these (not saying he doesn't load).
Click to expand...
 
ballmachineguy said:
But for starters, you are having a conversation in this thread with someone (El Cap) who has been trying to hit a modern forehand for 15 years and has still not hit a single ball with one.
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Oh I've had my fair share of disagreements with the Curious thought process and the way he reaches some of his conclusions over the years. So we agree on that. I'd like to say I was right every single time, but that is statistically unlikely.

Also, I think zero is a little harsh, and I've seen a video where he was hitting some nice looking topspin forehands and both you and @zill even complimented him on the stroke. I believe it lasted one day, which was really disappointing.:whistle:
 
Rosstour said:
Senior player? That dude is like 37-40 lol
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OK, I thought he was 40 and 40+ is senior according to all the kids these days! Sorry to break it to you. Anyway, you got the point, and that guy already has a left knee issue. It might not be a problem and I could be wrong, but I don't see many pros hitting most of their forehands like that.

liimey86 said:
Thanks for posting this vid. That real time side view of Djoko hitting rally groundstrokes is so great re seeing his forward leaning balance, and re watching what he does with his weight and balance out of the split step landings.
Click to expand...
I love that video - several different angles and you can see how he does his best to not get pushed back; the left leg often comes up slightly with a small step forward as he hits when he is under pressure. I will occasionally do the opposite!
 
AnyPUG said:
All flips are rotational/ elliptical. Some are slow and large, Fed etc have smaller and quicker and hitting side flip. That's okay, you are calling them by different names and no crime in doing that.
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The 2 minute tennis video I linked from Ryan with a timestamp discusses this. Did you watch it @Curious?
 
In physics, power is an an instantaneous thing, watts at an instant of time. Once the feet have left the ground, is the power from the feet 0 watts?

FYI, Bahmonde was one of the few tennis biomechanics analyst that actually measured or calculated power for tennis strokes in watts.

Power is most often used in a conversational way.
 
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Digital Atheist said:
Slow mo for identifying balance and ground forces is deceptive and real time is better imo. Watch him hitting live here, from multiple angles.

That is a great video to see how he doesn't excessively load into his legs and he is crushing these (not saying he doesn't load).

@Chas Tennis posted an older video of a senior playing changing from a "linear" stroke to a rotational modern forehand, but the leg loading on the right knee was excessive and ridiculous imo (especially for a player with a knee issue, this might screw the other one in short order and then he has two bad knees).

It seems like the coach is recommending he hit almost all forehands like that. I couldn't see that player lasting long with such a technique at his age. Compare that to joker and make up your own mind.
Click to expand...
I think that Djokovic aligns his pelvis so that the muscle cells have a favorable length to exert forces over the range for his strokes. Muscles cells can shorten with reduce forces as they become too short or too long. See Sarcomere Cross Bridges and Range of Motion..... He tends to often place his feet at a 45 degreeish angle, in my opinion, to the ball trajectory or to his intended shot trajectory in order to align his pelvis for the stroke.

See the pelvis angle on Djokovic's forehand? That looks familiar to me as a stance that he often takes for forehands. With trunk/spine twisting his muscles have a favorable length for his forehand, in my opinion. Notice also the tilt of his upper body.
 
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The power absolutely and scientifically comes from the ground for one undeniable reason. Movement requires a slight knee bend. The amount is close to 200ms. If you are already pressing the ground bending the knee and engaging the balls of the feet, you get additional 200ms second to stretch the body and release elastic energy onto the incoming ball. It means the power source is then ever present ground against which we press the joints to accomplish movement.
 
AnyPUG said:
The power absolutely and scientifically comes from the ground for one undeniable reason. Movement requires a slight knee bend. The amount is close to 200ms. If you are already pressing the ground bending the knee and engaging the balls of the feet, you get additional 200ms second to stretch the body and release elastic energy onto the incoming ball. It means the power source is then ever present ground against which we press the joints to accomplish movement.
Click to expand...
Nishikori jumps off the ground for many of his forehands.
(My sound was low. If so, use captions.)
Watch on Youtube to single frame. Use period & comma keys.

Single frame through Second 16.
"Watch on Youtube" to single frame. Use period & comma keys.

When his feet are off the ground, his power comes mostly from his trunk untwisting. Looks like Stretch-Shorten-Cycle of his abdominal/spinal muscles are supplying much of the power to accelerate his racket head speed. The power from the feet has ended by the forward swing.

I don't know of a single one sentence stroke description that has ever helped understand a tennis strokes. But they are easy to say - with confidence - but no evidence ..........and the forum posts go on, and on....................

One thing is for certain, energy for all tennis strokes comes from breakfast.
 
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10sbeast888 said:
well VP - I just realized something.

the right sequence does matter... in terms of tennis longevity.

this is a very bad combination - pushing the ground to start a swing + loading leak.

this puts tremendous stress on your lower body joints in a very leaky stroke, which does not produce power efficiently... but the bigger problem is more INJURY RISK.
Click to expand...

what kind of coach that didn't know right sequence does matter? :) Right sequence matters in all things, mister.


So, how exactly do you propose we swing? keey saying "rebuild" will not help anybody so don't say it.

Are you saying: ignore the lower body and just swing the shoulder or the torso?
 
Digital Atheist said:
@Chas Tennis posted an older video of a senior playing changing from a "linear" stroke to a rotational modern forehand, but the leg loading on the right knee was excessive and ridiculous imo (especially for a player with a knee issue, this might screw the other one in short order and then he has two bad knees).

It seems like the coach is recommending he hit almost all forehands like that. I couldn't see that player lasting long with such a technique at his age. Compare that to joker and make up your own mind.
Click to expand...
IMO, what that guy is teaching is not the best way to hit with a more open stance. (loading mostly on right leg/hip).
It is more important to be balanced. The legs are a base from which we use to align our upper body and make our unit turn, etc.

That is a great video of djokovic. We can see that he keeps his feet moving, has a wide base, and his knees are bent almost the entire time, making it easy to change directions and coil his upper body in preparation to swing.
 
Curious said:
Why even?
Click to expand...

Most don't invert. I always thought Nishikori just patted the dog without inverting. Also usually a pro level player either fully inverts (Sinner, Edmund, Sock) or don't invert. But both me and Nishikori are on a spectrum with me inverting more than him.

 
ProStaffFanatic said:
As I already said, there is nog single source. It's a sum of parts. Leg loading is one of those parts. And in this vid, I see a lot of leg loading.
Click to expand...
I looked at many forehands and saw what I interpret to be very questionable leg power from the ground. I saw power from the upper body.

"............ I see a lot of leg loading."
Do you have the video times of a clip or two of the leg power that you see?

 
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I think power comes from: bodyweight + rotation + the "elastic action" of the arm & wrist

You can say the bodyweight comes from the ground & legs because your legs pushing off the ground is what gets your bodyweight moving forward. Having the weight of your body transmitted through a punch or racket swing is the where the bulk of the power comes from.
 
zill said:
Most don't invert. I always thought Nishikori just patted the dog without inverting. Also usually a pro level player either fully inverts (Sinner, Edmund, Sock) or don't invert. But both me and Nishikori are on a spectrum with me inverting more than him.

Click to expand...
Forehand - the line between the 2 shoulders and the line between the 2 hips do not indicate much separation angle on turn back.

The racket shaft handle does not point at the ball for a time. More lag needed. The racket goes from angle of handle toward ball to head on ball for ATP forehand, your angle of swing is probably less. See ATP videos for what they are doing for lag.

Both these flaws show up in a few minutes of video comparison to an ATP forehand. I posted on forehand separation many times. Check that your grip is right for a straight arm forehand, which you appear to have. Straight arm forehand Federer (Eastern Forehand Grip) , Alcaraz, others. Bent Elbow forehand, Djokovic, (Semi-Western Grip I think.)

On one of your forehands, I saw the elbow too close to your side, that means the racket head is not out as far from the rotation axes (spine & shoulder joint) and its racket head speed would be less. Be aware of the angle of your upper arm out from your body by viewing ATP forehand videos.

WARNING - Forehand Separation involves trunk twisting and untwisting and that might be too stressful for many players and cause injury.
 
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onehandbh said:
That is a great video of djokovic. We can see that he keeps his feet moving, has a wide base, and his knees are bent almost the entire time, making it easy to change directions and coil his upper body in preparation to swing.
Click to expand...
Besides, it's not precisely a weak momentum what he's creating from the back leg into the body towards the left leg.

The Nishikori example is the ad nauseam repetition of the exception (that is not such) trying to be sold as the norm.
1. That jump is done with a lot of forward momentum; it's not just an "up" static jump.
2. Once in the air, the right leg is loaded foward. Then as the swing starts that leg also starts kicking down and up. In this case is purely the weight of the leg going in the opposite direction of the swing what stabilized the body.
3. Even with that leg kick, the hip can't rotate at the same angular speed as the shoulders, putting notorious strain on the spine. That is also a power leak.
4. The execution of the swing, severely stops forward velocity. This happens as well on regular forehand standing on the ground with the weight supported on the non-hitting-side leg.

There is an example of Kyrgios doing the same. Again, with a leg kick, that is not there for flashy reasons, but to stabilize the body: if the racquet+arm gains momentum in one direction, other part of the hitting side of the body needs to absorb it.

Momentum comes from the ground, and needs to be added to the body before the swing. The counter-rotational alternative is a power leak and an unnecesary strain source for recreational players.
 
Chas Tennis said:
I looked at many forehands and saw what I interpret to be very questionable leg power from the ground. I saw power from the upper body.

"............ I see a lot of leg loading."
Do you have the video times of a clip or two of the leg power that you see?

Click to expand...
Pretty much as good as any forehand

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And once again: there is no "single" power source. I don't agree with the blanket statement "power comes from the ground up". Power is a sum of parts.
The leg load is one of those parts. It's part of the whole chain. That leg load does / adds a bunch of things, one of which is powering up / initiating rotation / adding forward momentum
 
ProStaffFanatic said:
Pretty much as good as any forehand

SrrKyOJ.jpeg


S2h4Vxp.jpeg


pGkPq8a.jpeg



And once again: there is no "single" power source. I don't agree with the blanket statement "power comes from the ground up". Power is a sum of parts.
The leg load is one of those parts. It's part of the whole chain. That leg load does / adds a bunch of things, one of which is powering up / initiating rotation / adding forward momentum
Click to expand...

Please supply the video times so that I can look at the leg motions.
 
10sbeast888 said:
Better yet. Wear some heels and give it a try. It will be so obvious.
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When wearing (high) heels, it is a simple matter to utilize GRF pushing primary off the balls of the feet and the toes.

This happens with elite players wearing tennis shoes as well. This is dramatically demonstrated on the serve… we see both heels obviously off the ground during the trophy phase — prior to the leg drive.
 
10sbeast888 said:

obviously power does NOT come from the ground.
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@Rosstour

Nope, your video does not show what you believe it is showing— it does not prove your POV. I still see power utilizing GRF here.

I know of NO experts in tennis biomechanics who refute the idea that power is primarily generated from the ground up.

Can you provide us with either a published journal study or a scientific / researched article from a recognized biomechanics expert who refutes the ground-up KC?
 
Rosstour said:
You will never, ever get as much RHS from keeping two feet on the ground than by letting one of them leave it. Try it as many times as you like.
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It doesn’t matter whether you are driving off one foot or two — there is still a GRF in play.

When I taught myself a Safin-inspired mule-kick Bh (one-handed rather than dbl-handed, in my case), I could feel that I was pushing off and driving with the front leg considerably more than I had been with a more conventional Bh.
 
Curious said:
… The ground is just there doing nothing.
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@shug

Newton’s Third Law says otherwise. The ground is not doing nothing. However. the Earth is so massive we do not see the action / reaction of the Earth

Ground Reaction Force (GRF) is the force exerted by the ground on a body in contact with it, equal in magnitude and opposite in direction to the force the body exerts on the ground (Newton's Third Law). When pushing down or backward, the ground pushes back, allowing for walking, jumping, and running.
 
SystemicAnomaly said:
@shug

Newton’s Third Law says otherwise. The ground is not doing nothing. However. the Earth is so massive we do not see the action / reaction of the Earth

Ground Reaction Force (GRF) is the force exerted by the ground on a body in contact with it, equal in magnitude and opposite in direction to the force the body exerts on the ground (Newton's Third Law). When pushing down or backward, the ground pushes back, allowing for walking, jumping, and running.
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Sorry but I can only understand the gravity(earth’s pulling). My brain doesn’t accept the concept that the ground can also push me.
 
zill said:
Most don't invert. I always thought Nishikori just patted the dog without inverting. Also usually a pro level player either fully inverts (Sinner, Edmund, Sock) or don't invert. But both me and Nishikori are on a spectrum with me inverting more than him.

Click to expand...
I know what inversion means, but how is it different to what is often called the flip? If you could show a frame from your forehand or from Nishikori that might help me understand. For the most part, other than the serve, I just hit the ball and don't know much about all this stuff, so hopefully I am not sounding too stupid.
 
Digital Atheist said:
I just hit the ball and don't know much about all this stuff, so hopefully I am not sounding too stupid.
Click to expand...

100% that's what I do and also the pros. Some invert, flip or not. Many different looks/styles. I don't intend to invert at all but I do, a lot.

Even how spiny we hit our shots, we cannot control by and large.
 
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