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View Full Version : Pros do not seem to push off (begin kinetic chain) with their legs. What gives?


HunterST
12-05-2012, 07:01 PM
Looking to improve my kinetic chain and think maybe I don't push off with my lower body enough.

When I look at pros, though, I see them using virtually no leg push on their strokes. I've seen juniors with very strong "sit and lift" motions, but not pros.

http://www.youtube.com/watch?v=-24o_0SPc8k

I know that's casual hitting, but Murray is generating a lot of pace and I see no leg push.

Can anyone shed light on the role the lower body plays in the kinetic chain?

Cheetah
12-05-2012, 07:11 PM
it's just the way you think it is. they are using the ground force. simple physics. every action results in an opposite reaction of equal strength. when you push off with your leg you are pushing on the ground. the ground reciprocates and pushes you back. that is what actually happens. the energy from the 'ground force' is transferred all the way to your racquet head provided you don't have a broken link in the chain (no torso rotation, hitch in the swing, stiff movements, bad timing, etc.). If you have a good chain this force can be amplified by use of additional body part rotations during the upwards energy transfer.

you can start the kinetic chain w/ just a small push of one toe. or a slight push with your foot. it doesn't matter. a huge sit and lift isn't required.
it's all in the timing.

andy can still hit w/ good power even w/o a leg push because he has excellent timing and coordination. In those lazy shots he's starting his kinetic chain from his hips or torso.

LeeD
12-05-2012, 07:31 PM
I like Federer's warmup up vids better. Feet together, little movement, but good full early shoulder turn.
They are hitting heavy balls, in our point of view. When they start to try, their opponent's see the heavy ball, but not until then. Almost every pro, every shot, when the money starts to count, they move their feet, legs, and hips into every shot.

boramiNYC
12-05-2012, 07:51 PM
I think actually the legs provide more control than power as the level goes up thru precise positioning and timing. that way upper body can swing more freely more relaxed, which can generate alot of power. weight transfer from legs can add another dimension for power and control during match tho. but stability is the foremost responsibility of lower body. not power.

spaceman_spiff
12-06-2012, 02:44 AM
Watching a pro doing warm-up rallies and saying he's not using his legs is like watching Usain Bolt jog and saying he's not using all the sprinting techniques that coaches teach.

Find yourself a video of Murray or any other pro hitting full out and you'll see your leg action.

tlm
12-06-2012, 03:21 AM
Watching a pro doing warm-up rallies and saying he's not using his legs is like watching Usain Bolt jog and saying he's not using all the sprinting techniques that coaches teach.

Find yourself a video of Murray or any other pro hitting full out and you'll see your leg action.

I agree the pro's warm up strokes are just that warm ups they are just going through the motions, while their match strokes look entirely different.

eidolonshinobi
12-06-2012, 03:38 AM
I dont know what it was that night. I think maybe it was his fresh loss at the Australian Open against Djokovic, but honestly Murray didn't seem like himself. It's probably one of the reasons why he lost the first round of Indian Wells. Usually when I watched the other players warm up, they meant business.

I should know...because I shot this video.

I also have Rosol before I even knew him, I just filmed him because I thought he had some beast strokes.

I had a few more videos (none of Fed :( ) but ever since I moved I haven't gotten around to posting them up on the tube.

SystemicAnomaly
12-06-2012, 03:49 AM
Your thread title is a bit provocative, but misleading. In general, the pros use their legs quite a bit when competing. This is particularly evident when you see them coming off the ground -- one cannot jump without bending the knees and using a considerably amount of leg drive.

With this video and videos of Federer warming up, you do see less knee bend/leg drive. However, there is some. They do get some decent pace on the ball but, on average, not quite as when they are really hitting the ball in competition. The added knee bend used during competition enables pro players to generate added power more efficiently since they are recruiting more of the strongest muscles of the body -- the leg muscles. If one were to play a whole match without employing sufficient leg drive, it could possibly put too much stress on the shoulder/arm. While it may be possible to play for several hours with very little leg drive, it is not advisable.

Chas Tennis
12-06-2012, 05:08 AM
I have wondered about the same issue myself and see what the OP means. Very often - a majority of the strokes? - the pros are chasing a ball so hard that they seem to be doing all they can just to get there and the form of the stroke goes out the window.

This question could use some statistics for match play -

1) Given an easier ball to hit, what percentage of the time are the pros choosing to use leg thrust?

2) Overall, what percentage of the time, for given the match conditions, do they use significant leg thrust?

3) Under what circumstances are they leaving out the leg thrust?

An answer might be 90% of the time they use leg thrust on easy balls and 10% of the time they use it on difficult balls.

These percentages could be estimated using the stop-action of digital video recorders (DVR).

Possibly pros could also give a reasonable percentage estimate of what they are leaving out and why. ? An interview question. ?

It seems to me that what they maintain is the ability to contact the ball on a good part of a controlled racket face under very difficult incoming balls. A lot of the other form components seem optional for difficult shots.

(Unfortunately, for me the first thing that I leave out when rushed is looking at the ball - not good for where the ball is contacted on the racket face.)

TennisCJC
12-06-2012, 07:16 AM
I have seen many Federer groundstrokes where he uses his legs for lift and rotation. I disagree with you - pros do lift - Ferrer is another good example of lift and rotate. It is very common.

WildVolley
12-06-2012, 08:45 AM
The legs are always working, but yeah, you can hit a ball pretty hard without a lot of vertical movement from the legs and instead just by turning the hips a little.

In most cases, the legs are just the base of the kinetic chain and can add a little juice, but most of the power is coming from torso rotation (which leads to shoulder rotation) and arm speed. If you just swing your arm, you greatly limit the overall speed potential. If you rotate the torso to add speed to your arm, the legs are going to have to be involved at some level.

Also, the legs are used differently on different shots. The big servers use the legs to accelerate up and rapidly swivel the hips. The more powerful or rapid the jump, the deeper the racket drop loading tends to be. Guys like Dolgopolov will actually jump rapidly into the air to add extra topspin to his whip like forehand.

boramiNYC
12-06-2012, 09:02 AM
agree with WV. for more W grip swings could benefit from upward push of leg, but I get impression Fed mostly jumps to line up his shoulder to the ball height and swing remains fairly flat.

dominikk1985
12-06-2012, 09:23 AM
Sorry making such a statement based on youtube videos is stupid. you need force plates to study GRF. there have been plenty of studies proving GRF with force plates.

GRF are reality. no GRF means no kinematic chain. the push off is just not always the same strength. when they have time they will really load up on their leg and sometimes it might only be a slight push.

sureshs
12-06-2012, 09:52 AM
I have wondered about the same issue myself and see what the OP means. Very often - a majority of the strokes? - the pros are chasing a ball so hard that they seem to be doing all they can just to get there and the form of the stroke goes out the window.

This question could use some statistics for match play -

1) Given an easier ball to hit, what percentage of the time are the pros choosing to use leg thrust?

2) Overall, what percentage of the time, for given the match conditions, do they use significant leg thrust?

3) Under what circumstances are they leaving out the leg thrust?

An answer might be 90% of the time they use leg thrust on easy balls and 10% of the time they use it on difficult balls.

These percentages could be estimated using the stop-action of digital video recorders (DVR).

Possibly pros could also give a reasonable percentage estimate of what they are leaving out and why. ? An interview question. ?

It seems to me that what they maintain is the ability to contact the ball on a good part of a controlled racket face under very difficult incoming balls. A lot of the other form components seem optional for difficult shots.

(Unfortunately, for me the first thing that I leave out when rushed is looking at the ball - not good for where the ball is contacted on the racket face.)

I have also noticed that many pro strokes are hardly exemplary.

IMO, the "90% of easy balls" and "10% of hard balls" that you mention as when their strokes are correct, make all the difference.

It is like being able to return 20% of Karlovic's serves effectively versus 10% of them. That will make the difference in whether a pro can break him.

loci
12-06-2012, 10:50 AM
all world-class players get their power from their legs starting from their feet. their strokes are top-tier because of it and don't become that way by using faulty technique. take a look at someone like federer during his 2008 run to the US OPEN title.

http://www.youtube.com/watch?v=yo_zuz7bcLQ

his plant of that back foot on the forehand is the start of the kinetic chain, hence the lift of it as he begins his trunk rotation. power on that level comes only from the feet up.

TheCheese
12-06-2012, 01:53 PM
I think the kinetic chain is what is most important.

I think the degree of leg bend is really overrated when it comes to generating power. You can pretty much hit it just as hard as long as you have great timing with the kinetic chain.

dominikk1985
12-06-2012, 02:04 PM
I think the kinetic chain is what is most important.

I think the degree of leg bend is really overrated when it comes to generating power. You can pretty much hit it just as hard as long as you have great timing with the kinetic chain.

yes. the legs can generate a lot of power over a small range of motion (they are the strongest anyway when they are nearly extended-anyone can quarter squat more than full squat).

here is novak with not a lot of knee bend (maybe 120 degrees) but definitely pushing off (even leaving the ground)
http://www.youtube.com/watch?v=nbDzsGqqNYo

http://www.youtube.com/watch?v=PbsQ8gZLWyc

ramos77
12-06-2012, 02:21 PM
Andy is just hitting/warming up in that video. He's not going for power.

Not the best video IMO. Show a video of Pro's in a match and you will see them use their legs more.

edit: the fed video above shows it!

isilra
12-06-2012, 03:20 PM
Looking to improve my kinetic chain and think maybe I don't push off with my lower body enough.

When I look at pros, though, I see them using virtually no leg push on their strokes. I've seen juniors with very strong "sit and lift" motions, but not pros.

http://www.youtube.com/watch?v=-24o_0SPc8k

I know that's casual hitting, but Murray is generating a lot of pace and I see no leg push.

Can anyone shed light on the role the lower body plays in the kinetic chain?

Even in this video, Murray pushes off. Pushing off doesn't have to be like throwing a bullet to the sky all the time. Feet is the starting point of the kinetic chain if you want to start your kinetic chain from your feet. This is a practice session and he doesn't need monster power to hit the ball. So he doesn't go so close to the ground and push himself like a bullet but just takes some power from his feet by a relatively strong step. If he was playing Wimbledon final and need to crush a winner, than he would definitely lean and push himself so strongly to get that winner power. Also you don't throw yourself, even barely use your feet when you are playing at net because even if you start your kinetic chain from your shoulder, it will grant you enough power for your position. It's all about how much power you need and desire to take. Check this out;

http://www.youtube.com/watch?v=9dihL0_w6IM&feature=fvwp&NR=1

BU-Tennis
12-06-2012, 04:02 PM
The leg drive is highly overplayed by instructors, but is still vital in a complete stroke. The way tennis coaches talk about leg drive you would think 80% of the power comes from it, but this isn't the case. Very little power comes from the legs and the further you go up the body and along to the upper arm you greatly increase the amount of speed added to the stroke.

Plus, its more about rotation today, so you're not going to see people jumping up off the court too much unless its to hit a higher ball and they need to adjust the contact point. The legs are used to set the body position and provide a foundation for the stroke, and the legs push against the ground to help us generate more rotation in today's modern game.

tlm
12-07-2012, 02:38 PM
The leg drive is highly overplayed by instructors, but is still vital in a complete stroke. The way tennis coaches talk about leg drive you would think 80% of the power comes from it, but this isn't the case. Very little power comes from the legs and the further you go up the body and along to the upper arm you greatly increase the amount of speed added to the stroke.

Plus, its more about rotation today, so you're not going to see people jumping up off the court too much unless its to hit a higher ball and they need to adjust the contact point. The legs are used to set the body position and provide a foundation for the stroke, and the legs push against the ground to help us generate more rotation in today's modern game.

Not true just watch any pro video were they have time to set up on a forehand and you will see that they come off the ground almost every time. Just go to youtube and watch slow motion forehands of pro players. I am referring to the male players in match action not warm up strokes.

TheCheese
12-07-2012, 02:44 PM
Not true just watch any pro video were they have time to set up on a forehand and you will see that they come off the ground almost every time. Just go to youtube and watch slow motion forehands of pro players.

Just give it a try yourself. Does getting a really deep knee bend have a huge effect on the amount of power you can generate on groundstrokes?

Leg bend is hugely overrated. It's all about the kinetic chain. Adding a little extra leg bend will give you some boost in power, but it's not going to be night and day. If anything, the most important thing about using your legs is being able to adjust your strike zone to the ball.

LeeD
12-07-2012, 02:50 PM
Yes, legs are to get there, in position to hit the ball in your sweetspot.
Posture, solid torso, and arm stroke produces most of the power, in addition to speed/spin of incoming ball.
You still need both, unless your opponent hits right where you want, at the height you want, and the depth you want...spin, speed...

tlm
12-07-2012, 03:02 PM
Just give it a try yourself. Does getting a really deep knee bend have a huge effect on the amount of power you can generate on groundstrokes?

Leg bend is hugely overrated. It's all about the kinetic chain. Adding a little extra leg bend will give you some boost in power, but it's not going to be night and day. If anything, the most important thing about using your legs is being able to adjust your strike zone to the ball.

Here is an example of fed who other than when he is jammed comes off the ground or nearly does on most forehands.

http://www.youtube.com/watch?v=I_36O-nJUfQ

LeeD
12-07-2012, 03:17 PM
Looks to me, somewhere around waist high is where he'll jump or not, on his forehands.
E forehand grip.
What would he do with a stronger grip? Like strong SW?
And with the old conti forehand, most player's either sliced the high ball or jumped to get to the ball.

TheCheese
12-07-2012, 03:32 PM
Here is an example of fed who other than when he is jammed comes off the ground or nearly does on most forehands.

http://www.youtube.com/watch?v=I_36O-nJUfQ

Obviously you should do it if you can, because it helps. It's not the main source of power, is what I'm saying.

tlm
12-07-2012, 06:20 PM
Obviously you should do it if you can, because it helps. It's not the main source of power, is what I'm saying.

Thats true it is just one part of the power source.

5263
12-08-2012, 05:06 AM
Just give it a try yourself. Does getting a really deep knee bend have a huge effect on the amount of power you can generate on groundstrokes?

Leg bend is hugely overrated. It's all about the kinetic chain. Adding a little extra leg bend will give you some boost in power, but it's not going to be night and day. If anything, the most important thing about using your legs is being able to adjust your strike zone to the ball.

IMo what makes this confusing ...other than the OP vid was just a warm up that is
not a great reference for much about how they actually play... is how all these
items are strongly interrelated.

borami say legs are about stability which is largely true...but stability is about
great control, which is paramount for hitting big!
IMO the legs are more about TS and controlling the contact point....which are
also extremely important for hitting big; especially if you want to keep it in the court.

So maybe the leg drive doesn't contribute sooo much directly to generating
power, but contributes greatly to most things that help you generate and
control power.

SystemicAnomaly
12-08-2012, 12:31 PM
The legs can be a more significant contributor to power/RHS than some here give them credit for. Note that the leg muscles are some of the largest and most powerful in the human body. They are much more powerful/stronger than the arms -- easily twice as much or more power/strength in the legs than the arms. With that in mind, it does not require a huge leg action to produce a decent amount of power. A moderate amount of leg drive goes a long way.

It starts with GRF (ground reaction force). By moderately bending the knees, the legs can take this GRF and generate some leg drive that is subsequently transferred to the hips/pelvis for the start of a powerful rotation of the hips followed by a rotation of the torso.

Obviously, a wheelchair tennis player can generate a fair amount of power/RHS without leg drive and hip rotation. However, this puts more demands on the torso/shoulder and arms. With leg drive and hip rotation, we can generate power more efficiently -- with less demands on the upper links of the kinetic chain. These latter links do generate power on their own but they are also transferring accumulated power from previous links in a more efficient manner.

The following are quotes from some PhD's in the field of biomechanice -- Roetert, Knudson, Groppel & Kovacs...

"Vigorous extension of the lower extremity in classic closed stance forehands creates greater axial torques to rotate the pelvis and hips than not using the legs... in open stance forehands, it is logical that vigorous leg drive also transfers energy to trunk rotation... "

"Vigorous axial hip and upper-trunk rotation allow for energy transfer from the lower extremity to the upper extremity... "

"Some of the energy stored in this leg is converted to predominantly upward (vertical linear) momentum but also forward (horizontal linear) momentum. This leg drive utilizes ground reaction forces and is critical for linear to angular momentum transfer and the development of high racket speed... "

http://www.scribd.com/doc/46802858/Bio-Mechanics-of-the-Tennis-Ground-Strokes (http://www.scribd.com/doc/46802858/Bio-Mechanics-of-the-Tennis-Ground-Strokes)