So, you admit pros use the legs. And, we all know they use the legs to drive up on the serve BEFORE anything that resembles forward movement of the hitting arm. But, you insist that the sequence isn't legs, hips, shoulders and finally arm on groundstrokes. Why do the top coaches teach to load into the outside leg on ROS and on wide groundstrokes? On wide groundstrokes we have seen the best coaches in the world teach to load the outside leg behind contact and to use it to push your weight into contact and back into the ball. This loading on the outside foot happens BEFORE forward swing on any kind and the rotation forward drives the upper body too. So, your theory is they catch their weight on the outside foot and then swing from the upper body without action from the legs and hips? Sorry, that ain't happening. It would be a totally spastic movement. Watching Musetti and Cerundelo in Rome right now. They load on the back outside leg and rotate on that leg to initiate the swing over and over again. Also, on ROS, players load and move forward to contact by pushing off the back leg. Coach teach to load and push BEFORE contact so you movement is forward at contact. Sorry man, but sometime I think you just like to be contrarian to try to make a name for yourself.
Power Comes From The Ground
- Thread starter shug
- Start date
I strongly suspect your interpretation is not what beast is trying to convey. From the point of view of learning sequence, the leg load in any stroke is much lower priority compared to the proper structure of upper body, arm and wrist, hand etc. Sure, everything starts from the ground since we got to learn to stand up before anything. After that, learning the way upper body has to behave is lot more complicated than use of ground reaction force.
I'm sure there are people who insist on perfecting leg, ground, movement before learning to use the upper body. No amount of argument will convince people with a different view on tennis priorities.
10sbeast888
Legend
it's all in the skater vid... not my idea.
Shroud
Talk Tennis Guru
Maybe. But for the one handed bh?? Ever seen curious screw up the legs and fail miserably for years and years?
May be not. If legs are so important, why doesn’t anyone hold the racket with their legs and play? If legs are critical, I bet someone would try that. Actions speaks louder than words.
Shroud
Talk Tennis Guru
Are you on meds?
No, may be that’s the problem?
liimey86
Semi-Pro
To my experience, the proper structure of the upper body, arm, shoulder is quite different/distinct for a hitting-with-the-legs biomechanic.
Vs the structure/config (and the various upper body muscle contractions I guess) when instead using the upper body and arm to throw the racquet.
These are two quite different ways to hit a ball.
IMO either can be learned and used to hit a decent rec ball. Neither is "wrong". But upper-bodying the racquet has a lower plateau re power/pace/spin and more risk of injury as you try to hit at that upper limit.
10sbeast888
Legend
10sbeast888
Legend
your still in the YDKWYDK.
user92626
G.O.A.T.
the middle is the money
Actually, there were coaches decades ago that strapped frames to the thighs of players but I don't think that is productive. Of course the upper body is more important. You could play lower intermediate level tennis by simply pushing the ball around with your arm and hand. The angle of the racket face at contact is perhaps the single most important factor because if you position the face correctly and maintain the face for a short push of a swing, you could be consistent, place the ball and beat a lot of tennis players. But, legs are part of using the core correctly and as the many videos of pros in this thread prove, pros use leg drive to move the core up and around on nearly every groundstroke and the serve.
liimey86
Semi-Pro
repeating that over and over is some seriously nuanced and clever stuff
nice contribution
10sbeast888
Legend
how old are you... old enuf to be in the 'not attention shortage' crowd?
The message I get from your post is that security is very important, billionaires spend millions on personal security and we should emulate these successful people and should spend lots and lots of money to make sure we are not beaten up and mugged on the street.
I have sympathy for folks who argue that we can ignore the use of legs until we know how to use the upper body parts.
I am focusing more on the upper body here
liimey86
Semi-Pro
Great to hear a detailed description of your ideas on this. Admittedly I haven't been able to understand some of the specifics above. If you're interested in another go at it, I'm interested to read.
By "rotate the feet", do you mean rotate pelvis (aka lower body feet+legs+pelvis)? Or something else.
Also, in first sentence, I think you mean 'feet push against ground in a clockwise direction"? Not trying to be nit-picky, just trying to make sure I know what you're meaning.
10sbeast888
Legend
.
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LOL this must be the best post ever on this forum.
10sbeast888
Legend
ballmachineguy
Legend
Question #1 Yeah, sure. Any or all of those lower body parts rotating in an effort to initiate the swing would be a problem.
Question #2 No. I meant what I wrote. The feet pushing the ground would be active. The feet get a counter clockwise force from the upper body and therefore the hips trying to turn. The ground, with feet planted resists this. I know the ground doesn’t push, but since it is countering the counter clockwise force of the feet, I said it pushes clockwise. The feet are actually passive as far as rotation is concerned.
ppma
Hall of Fame
Why? On regular momentum transfer groundstrokes you can see the hitting side leg go forward before the hand accelerates. That leg coming forward is not following the swing. Actually, the leg load and unload starts even before; when the non-hitting foot is not on the floor, and the back leg is carrying all the weight, the action of setting the front foot on the floor is the result of the generation of forward-lateral momentum from the back leg into the front leg. That is by pure geometry a rotation in a semi-open stance.
But I see the issue. When the player tries to rotate the feet counter clockwise, it's not the feet what they are rotating, but the whole body. Of course, the pushing is clockwise, but the reaction (that applies to the whole body starting from the feet) is counter-clockwise, which is the rotation that the body needs to swing. In summary, to get a reaction from the ground, one does the opposite. You can't jump moving your feet up, but actually pushing down; but I think anyone is past that lesson.
ballmachineguy
Legend
The leg does follow the swing. You use the lower body to drive the upper body. You don’t pull the upper body by starting with the legs. What body parts you try to move first will dictate whether sentence 2 or 3 happens. If you are throwing a discus, it is sentence 3. If you are driving a tennis ball over a net and short of the baseline it is sentence 2. Our sport has a distance limitation that requires it be the upper body initiates and the lower drives it through contact.
ppma
Hall of Fame
Happy idea or there is academic reading on this?
Upper body cannot rotate efficiently without getting momentum from theg round just before, and that does not mean that the legs "move firtst".
In any case, what you state are against the readings posted before with time sequence measurements, so either the subjects on whom the measurements played wrong or you have a very extrange understanding on body dynamics.
ratherlosethanpush
Rookie
This is essentially my current understanding of it.
It's been years since I've had access to the journals and studied it.
movements are usually split into preparation action and recovery to aid analysis of it.
With the racket sports I've studied on force platforms and 3d digitisation you can basically prepare in any order, but action is starting from the ground (some redefine this point a bit as often upper body is still moving back whilst the lower body has started the forward impulse). The larger muscles are usef and we (himans) use rotational forces for efficiency and the larger more proximal body parts go first then slow down to pass the momentum on to the smaller more distal parts which benefit also because they are smaller. Max speed without a ball of the racket would usually occur through contact and then recovery starts and the order more or less reverses at this point, which I guess could confuse some.
We also have specific demands to recover so in tennis we need to recover to a place in time, in golf we dont need to so we dont need to adjust this process.
ballmachineguy
Legend
I don’t give a flying &@$! about academic readings or what happens when. In trying to teach tennis, you tell the person what to do first. Read the title of this forum! If you deliberately try to start the swing with your legs, you will have a !&i$ groundstroke.
10sbeast888
Legend
lol you guys still going at it
ppma doesn't play tennis.. he said it himself. there is no way to verify anything.
ppma doesn't play tennis.. he said it himself. there is no way to verify anything.
10sbeast888
Legend
'not playing' is a real limitation, in terms of actually connecting the theories with the actual tennis.
user92626
G.O.A.T.
so two guys who don't play tennis are arguing each other over tennis?lol you guys still going at it
ppma doesn't play tennis.. he said it himself. there is no way to verify anything.
Smecz
Professional
Huge true that is agree,but I don't know myself...
Just pull the natural draw below 18 kg, for example 16 kg, and I have shots like a bullet...
Or the forehands hit by Muster or Rune in a cast, practically without using your legs... rather, you push off from the bench or chair...
Or the next example of Pablo Cuevas's crazy forehand in the match against Zverev, also bordering on ground power...
And last The source from the Chatgp:
If you were standing almost still, just swinging your arm in a forehand motion, and still managing to return extremely fast balls, the question is whether there is still “power from the ground.”
1. What happens when you stand still?
If you:
then:
F_{ground} = m \cdot a
So the ground is still supporting your body mass, but it is not significantly contributing energy to the shot.
2. Where does the power come from then?
In this scenario (fast ball, minimal movement):
But:
the majority of energy comes from the upper body, not the legs.
3. Is it still “power from the ground”?
Technically:
So:
4. Why can you still return fast balls?
Because:
That’s why players sometimes:
5. Key principle
The less leg drive and weight transfer you use, the more the shot becomes “arm-driven” rather than “ground-driven.”
Summary
Just pull the natural draw below 18 kg, for example 16 kg, and I have shots like a bullet...
Or the forehands hit by Muster or Rune in a cast, practically without using your legs... rather, you push off from the bench or chair...
Or the next example of Pablo Cuevas's crazy forehand in the match against Zverev, also bordering on ground power...
And last The source from the Chatgp:
If you were standing almost still, just swinging your arm in a forehand motion, and still managing to return extremely fast balls, the question is whether there is still “power from the ground.”
1. What happens when you stand still?
If you:
- don’t step
- don’t transfer body weight
- only swing your arm
then:
- you are generating almost no new energy from the legs
- but you still have ground contact that provides balance and stability
F_{ground} = m \cdot a
So the ground is still supporting your body mass, but it is not significantly contributing energy to the shot.
2. Where does the power come from then?
In this scenario (fast ball, minimal movement):
- mostly the arm and forearm
- some torso rotation
- minimal contribution from ground reaction through balance
But:
the majority of energy comes from the upper body, not the legs.
3. Is it still “power from the ground”?
Technically:
The ground is still part of the system (it stabilizes you)- Without it, you couldn’t control balance
But there is no effective energy transfer from legs into the shot
So:
- the ground is no longer a power source
- it becomes a stability platform
4. Why can you still return fast balls?
Because:
- the incoming ball already carries a lot of energy
- your job is mainly timing and redirection
- you can block or counter rather than generate full power
That’s why players sometimes:
- shorten the swing
- “block” the ball
- use the opponent’s pace instead of creating their own
5. Key principle
The less leg drive and weight transfer you use, the more the shot becomes “arm-driven” rather than “ground-driven.”
Summary
- The ground is still physically involved (balance and support)
- But in this case, it is not a power source
- The shot’s energy comes mainly from the upper body and the incoming ball’s pace
SystemicAnomaly
Bionic Poster
Karma. You reap what you sow.
SystemicAnomaly
Bionic Poster
If the truth is all revealed in your golden skater vid, why are biomechanics experts in tennis not on board with this?
I win!
Happi
Hall of Fame
user92626
G.O.A.T.
Nice. I think this is the skater vid that our Beast man often refers to.
ppma
Hall of Fame
Not even Fed was able to dance on the floor like that.
ballmachineguy
Legend
I thought people on space missions do all sorts of acrobatics in space. I doubt they are pushing off of sensitive equipment. Anyway, snowboars, they **** their arms in the opposite direction and they whip there arms in the direction of rotation attaining 1200 degrees of rotation in the half pipe.. There feet are on a slippery surface. They aren’t rotating with the lower body. Ever wonder why the off arm reaches out along the baseline during the coil or you leave your tossing arm up until you want to swing at the serve? It starts rotation and tennis players only need 90+ degrees.
The above is a good example. Don’t want hear about it not being tennis. Tennis players only want to get fast rotation because that is the power. Arm doesn’t swing at the ball independent of the torso.
Oops, can’t use a rooster word on here.
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ppma
Hall of Fame
I was suggested this reel and perfectly fits here.
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Regular forehand with healthy leg: back leg pushes to create rotational momentum pivoting on front leg.
Forehand on office chair: The front leg has to work hard to generate the rotational momentum around the chair axis.
Both actions from the ground happen before the swing acceleration starts from the hand.
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Regular forehand with healthy leg: back leg pushes to create rotational momentum pivoting on front leg.
Forehand on office chair: The front leg has to work hard to generate the rotational momentum around the chair axis.
Both actions from the ground happen before the swing acceleration starts from the hand.
shug
Rookie
The key word is "Hypothetically", I did not say set a tennis player up in the space shuttle., I said "in space".
ppma
Hall of Fame
So you understand how is the snowboardwer generating the rotational momentum from, or we have another 'skater vid' case? Because that's a ground-up motion as well.
ballmachineguy
Legend
ppma
Hall of Fame
When the diver leaves the platform, they coil legs and back.
When they are already falling but still in contact with the platform, there is action from the arms. One pushes doen and the other pulls up. The rotational momentum is already there in the body.
Then, the speed of rotation increases because arms, that were first away from the body come tucked together with the torso. As it's known, angular(rotational) momentum is conserved. So, mass concentrated closer to the rotation axis, implies that such mass must rotate faster than when that mass is further from the axis.
How is this related to tennis? Tennis groundstroke swings are from close to the body to away from the body. The arms are not starting the rotation because they can only steal energy from the body; the divers start the rotation from the contact to the heavier object (the platform).
Back to the snowboarder. Do you understand how he is creating rotational momentum?
ballmachineguy
Legend
So, now coiling is just bending the legs?
A tennis players starts with the arm stretched way out in front and then the hand ends up by the shoulder. It gets pulled in to rotate faster, just like the diver.
The snowboarder yes. Uses the arms to rotate. Feet aren’t even planted.
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SystemicAnomaly
Bionic Poster
From MDPI, PubMed, Space Exploration Stack & misc other sources:
Humans can execute rapid torso rotations in zero G. However, because of the law of conservation of angular momentum, attempting to twist your torso without bracing against a fixed object will cause your hips and lower body to rotate in the exact opposite direction rather than turning your entire body.
The Physics of Space Rotation
Because there is no gravity or friction to anchor your feet, your body behaves as an isolated system. If you attempt a rapid, sharp twist at the waist:
- The Action: Your upper body twists to the left.
- The Reaction: Your lower body (pelvis and legs) instinctively twists to the right to balance the momentum.
- The Result: You end up in a coiled, twisted position, but your overall orientation in the cabin remains unchanged.
Astronauts maneuver themselves in weightlessness using specific biomechanics rather than simple torso jerks: [1]
- The Cat Twist: Humans can execute full 180-degree body flips, much like a falling cat, by moving their limbs in a distinct "hula hoop" sequence (bending, extending, and rotating hips and arms sequentially to shift the mass distribution).
- Reaching and Grabbing: The easiest way to turn is to simply push off a wall or grab a handrail.
SystemicAnomaly
Bionic Poster
@shug @Digital Atheist
Check out post #447 for the details & limitations of astronaut “astrobatics”.
With your snowboarder video, I’m still seeing a GRF — there is most definitely still a GRF present that enables spin / rotation.
From AI / Scientific American:
When a snowboarder performs an aerial or flat-ground spin, the rotation fundamentally starts with a ground reaction (GRF).
Because a snowboarder is a closed system while in the air (meaning the total amount of angular momentum remains constant), all the energy needed to spin must be generated before the board leaves the snow.
Here is how a snowboarder generates and utilizes this force to initiate a rotation:
- The Wind-Up: The rider typically begins by twisting the upper body (head and shoulders) in the opposite direction of the intended spin, storing tension in their core muscles.
- The Pop (Extension): To leave the ground, the rider bends their knees and quickly extends their legs (a rapid downward and then upward leg movement) to push off the snow.
- The Ground Reaction Force: Newton’s third law states that for every action, there is an equal and opposite reaction. When the snowboarder forcefully extends and pushes into the snow, the snow pushes back with an equal upward and outward force.
- Creating Torque: By releasing the "wind-up" during this explosive extension, the rider converts that upward ground reaction force into rotational torque. This torque creates the initial angular momentum that drives the spin in the air.
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ppma
Hall of Fame
They aren't because he is on a board. Ask yourself; why in the trick of the video the snowboarder first does a turn to his left and then len to his right.
The diver moves the arms but not in isolation; there is torque applied from the arms. As SystematicAnomaly points out, not overall body rotation can be achieved without stealing momentum from a fixed heavier object.
ballmachineguy
Legend
Watch the snowboarder again. His arms start the rotation long before anything happens with the legs. Same thing happens on a forehand, just not as wildly.
