A good forehand - trunk rotation stops before making ball contact

[directionals]

I was looking at a Fed fh video and noticed that his trunk rotation stops when he chest faces the target(opponent court). This lets his racket arm and racket catch up. After making contact with the ball, the arm swings across his chest and then drags his core and now the trunk rotation starts again until his chest somewhat faces the left fence. Is this a significant check point in a good fh? I always thought the trunk rotation was continuous from right to left (for a rightie).

See this Fed video: http://www.youtube.com/watch?v=EAE6AcxAGdA&t=38s

I watched Djokovic's videos and the check point is not as apparent.

 

[dominikk1985]

yes. energy is transfered by decelerating shoulder rotation and then have an independent arm.

if you use the WTA "pull" FH the arm/racket structure is pulled through (dragged) by the body rotation but if you use a segmented kinetic chain the rotation happens mostly during the load (while the racket lays back after PTD).

 

[Pet]

My advise is that don´t make it conscius or you will hurt your game.

 

[JohnMartin]

yeah - as many have mentioned - figure out the swing path first, the body will know how to generate power.

 

[Topspin Shot]

The Lock and Roll guy (Tae I think his name is?) likes to emphasize how the unwinding of the trunk precedes the forward swing. It's part of the whole kinetic chain; lift, then unwind, then swing from the shoulder, then make whatever movements are necessary with elbow and wrist depending on your grip. I personally wouldn't stress this overmuch in my teaching; I like to focus more on swing path and let the player discover the kinetic chain for himself.

 

[TennisCJC]

This is a good thread in my view. I don't know the proper terms but I agree that rotation fires from the legs upward in sequence - legs, hips, shoulders, arm and racket. But, there is stopping action of each segment and the energy is released into the next segment. You see some players who don't stop the core and spin the core and back leg around as they hit. I think this actually robs you of RHS, balance and control.

 

[RetroSpin]

I agree that this is a good thread topic. The rotation dynamic is not examined in very much depth in tennis instruction and often relies on vague descriptions of feel or assumptions that may not be born out by analysis.

What I see is a pretty significant difference in the FHs of Rafa and Nole. They may actually represent the polar extremes of technique. Rafa opens up early to get his left shoulder in extreme external rotation and seems to rely more on throwing the racquet at the ball. Nole moves his arm more in sync with his body and seems to rely more on rotation to power his swing. I think Fed is somewhere in between but more towards Rafa. Of course, they both use an extended elbow FH as well and Nole uses a bent elbow. I don't think Nole's rotational stroke would work very well with an extended elbow.

One would expect Nole's technique to be more consistent but less powerful, and that seems to be the case with these pros.

 

[directionals]

At 1:27 of the video, Fed hits an aggressive FH with a neutral stance. The stoppage in the torso rotation is very clear before the ball is struck. In watching Rafa's videos, his torso kind of stops before the ball is truck but it's less apparent then Fed's FH's.

 

[dominikk1985]

there is certainly decelation of rotation before ball strike in good forehands.

this is also known in other sports. track and field has known this for years. dicus throwers and shot putters call that move the "block".

it was also decribed in baseball.

from a dissertation (study on minor league hitters):

The batter’s maximum pelvis
rotation velocity was achieved early in the swing acceleration phase, rising to a peak of
581°/s by −70 ms, later slowing to 287°/s by BC. As the batter rotated his entire body
during swing acceleration, the lag between the pelvis and the upper trunk decreased from
−18° to −2° (global upper trunk angle: 2° to 75°), and this was facilitated by a maximum
upper trunk rotation velocity of 766°/s achieved at −57 ms. This value gradually fell to
430°/s by BC.

http://scholarlyrepository.miami.edu/cgi/viewcontent.cgi?article=1550&context=oa_dissertations

federer and especially nadal have the most prominent stopping. djokovic seems to rotate through more but I'm sure he is also decelerating a lot although not quite to zero like fed and nadal who seem to stop the body and really whip through the racket. female players also often rotate through more.

 

[WildVolley]

Think of it as cracking a whip. To maximize racket head speed, the earlier parts of the kinetic chain have to slow in order to pass the velocity on to the hand and ultimately the racket face.

So it optimally start with the hips and moves up to the torso and shoulder rotation which should be slowing if not necessarily stopped at contact to maximize arm and racket head speed.

 

[boramiNYC]

Imo, what's impotant about the rotation stopping is noticing that there is an optimal contact point relative to the pelvis orientation and how consistently good players control the pelvis orientation even while violently swinging the racquet. The legs (ankle, knee bend, weight shift to one hip joint) allow the pelvis to rotate quite a bit and this is an important piece of the chain that stretches the obliques for trunk rotation that allows powerful upper trunk and shoulder rotation. But the rotational potential becomes only useful as long as you can control the pelvis position relative to the contact point. And this control includes holding it firm to allow the rest of the chain to do their work and again release to absorb the shock of the swing and slow in controlled manner and recover for next move.

Many rec players don't have clear idea where this optimal position is relative to pelvis or don't care enough about it or just lazy hoping the strike zone is as big as their laziness or just don't have good control of legs and pelvis, etc.

So it's a good topic if it raises awareness of these issues.

 

[RetroSpin]

I thin the critical issue is how much the arm lags behind the body. Rafa clearly lags it a lot. Nole not so much.

I think concentrating on the body's rotation stopping is a mistake. The hips can only turn so far. When they get there,they will slow down and stop. If you try to stop them prematurely, you will end up arming the ball or worse.