generating backward rotation

6 comments ↓

#1 Chris on 11.08.12 at 10:37 am

Actually, I am a bit of a biomechanics “geek” and I am not sure that I agree with your concept of an “indirect” force. Honestly, the concepts of “direct” and “indirect” forces really aren’t used too often in the biomechanics texts/literature that I’ve read. I have seen these terms more in physics with an “indirect” force being defined as a force between two objects that aren’t touching – say like a magnetic force. In this situation, your body is in contact with the floor, tramp, etc. and so the vertical ground reaction force (vGRF) is direct. The muscle force or torque generated by the glutes/hamstrings/adductor magnus and any other contributing hip extensor could be considered as the “indirect” force, I suppose. What is really happening is that you are creating a torque by moving your center of mass away from the line of action of the ground reaction force while still in contact with the ground. This ultimately is what produces the rotation. Of course, this is a pretty simplistic overview neglecting the transfer of momentum that ideally occurs from the “stopping” of the upper extremity to the rotating body as a whole.

#2 blantonnick on 11.08.12 at 10:51 am

Reminds me of Arkaev’s book “How to Create Champions”:

“A well-mastered somersault technique (stretched somersault) for which judges make no deductions in the junior rankings will be a brake on mastering more complex somersaults (a double and a triple, for example) if during flight the arms are immediately let down, while the body is considerably ‘convex’ (bent). This pose is characterised by a smaller moment of inertia of the gymnast’s body in relation to his transverse axis by comparison with a fully straightened body and requires less angular momentum given from support. Ultimately less effort of interaction from support is required to perform this stretched somersault.

It is another matter when a gymnast performs a stretched somersault at maximum height with fully straightened body in flight and arms raised up.”

#3 coach Rick on 11.08.12 at 11:31 am

We’re using that term in the Canadian coach education system.

On take off, hips “press” forward … an equal, opposite and concurrent reaction force pushes the upper and lower parts of the body. Since the feet don’t move, there’s an equal, opposite and concurrent ground reaction force generating backward rotation.

In fact, that’s the major force rotating the body in a gainer backward somersault.

I doubt were disagreeing on anything, Chris.

But in Canada we’ve downplayed the importance of biomechanics as it so often generates more heat than light.

Many of the best coaches in the world couldn’t care less about mechanics.

#4 coach Rick on 11.08.12 at 11:35 am

I first saw layout with arms up used off Horizontal Bar — perhaps 1972.

It was prep for double back, of course.

It’s ideal for beginners to learn how to use their hips on takeoff, too.

#5 Valentin on 11.09.12 at 1:21 am

I feel like I have to chime in here

1- Overall if this drill can help a kid understand a correction and make improvement as a result, than regardless of how its done or ideals then it all good. I personally don’t care if it is this drill or them standing on their head clucking like a chicken that will do the trick.. I would use it if it is in their best interest and in the name of progress in their goals.

However! I personally don’t feel that looking at the way the drill is performed, that it will have the same level of benefit as it is portrait. Actually she is whipping her head and shoulders back quite considerably to be able to generate that rotation and, losing quite a bit of height a result. I have to assume that the drill is performed as intended by Marvin Sharp, or why would he use it as an example.. And if he doesn’t have anyone who can do the drill perfectly, than that leads me to think the drill is not as good as it seems.
So basically the coach in me says, I would use it to help the gymnast understand the concept of the hip involvement, but I would be cautious to allow my gymnasts to continuously perform the drill in the way it was done. Plus the twisting version is definitely not teaching tilt twisting. And I would dare someone to use this method to teach twisting from start. If someone does please report, and I will try myself.

2- I disagree with you Rick that
“Many of the best coaches in the world couldn’t care less about mechanics “. I highly doubt that many of the so called best (Which in itself needs clarification) ” could not care less “. Amy coach who does not understand his sport and the material that he is teaching, I cannot! possibly see them being a good coach. And in order to be able to understand those things you got to know to some degree your gymnastics mechanics. From my experience many coaches use mechanics to try and sound like the know what they are talking about more so than anything. When in reality many simply don’t. I myself don’t know 1/2 as much as I would like too but that is why I work on studying it.

Personally however, I don’t feel that the need to talk detailed mechanics is of much actually coaching use. They key if for the coach to have a very good grasp of the correct knowledge, so he can pass on to the gymnast in terms they can understand (we usually do this with drills, diagrams, explanations, metaphors etc). Like Einstein said ” If you can’t explain it simply, you don’t understand it well enough ”

Valentin Uzunov
TheGymPress.net

#6 coach Rick on 11.09.12 at 1:55 pm

Most famously, Steve Nunno coached Shannon Miller to become one of the best gymnasts in the world. No apparent knowledge of biomechanics.

Bela always claimed he doesn’t know much about mechanics.

Perhaps the era of the hollering, motivation coaches — like those — is ending.

I hope you’re right.

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