High flying kicks

[miked]

Check out the knockout jump hook kick used in competition at the tkd tutor web site.

It is sweet!



Mike

[Bill Glasheen]

Although it first seems the wrong way to do it, when performing a jump-spin kick, you must first jump, then spin, and then kick. Most beginners, and many advanced students, try to spin first. This means they barely get off the floor with the jump. If you start the kick before the spin, your leg will move away from your center of balance and throw you off balance. Keep the arms in a tight guard position; if they move outward, you will be thrown off balance, and, since you will not see your opponent for a moment when the head is turned, you need to protect yourself against a counter attack. Also, if the spin is done properly, your head will snap around quickly at the beginning of the jump-spin. When the head suddenly stops after the spin, it takes a moment for the brain to settle down and the vision to clear.

Bill, what do you make of this advice?

This seems counterintuitive.

Mike

What I make of it is that the person doing it isn't able to articulate what he does very well. There's something to what he is saying in the beginning, but it's not quite right.

The most important part of a jump kick is the jump. This is core muscle energy that you eventually must send into the opponent. Getting that right is important.

When you jump, it is possible to generate BOTH translational and rotational energy.

• Any translational energy put into the jump sends your center of gravity in a parabolic path, with the plane of the parabola orthogonal to the plane of the floor.
• Any rotational energy put into the jump will cause you to rotate about your center of gravity. That rotation can be changed somewhat by the movement of your arms and legs.

Now it IS true that you get the best snap out of a jumping, spinning kick if you apply a little bit of sequential summation of motion. In other words you twist one part of your body which stores energy in your biological torsion spring. You can subsequently release the energy of that spring into the kick. But because you're now in the air, there's no free lunch. You don't have the ground to push against in rotating. Consequently getting a good "jump/spin" before you execute the kick is important.

To understand how this is done, watch an ice skater do jumping spins. That generally is a pretty simple way to view it all.

There's one other principle of physics to consider here. That would be conservation of angular momentum. Basically when you start your spin, you will spin slower if your mass is distributed far away from the center, and faster if you pull the mass closer to the center. Consequently the load (torque) which you feel when you do the spin will vary by the degree to which the mass is spread away from the rotating center. In other words the angular (spinning) momentum is conserved, so redistributing the mass will change the appearance of things.

Ice skaters take advantage of this principle by having their mass out when they spin, which gives them a higher resistance to push against in the spin. If you match the load right, you get the maximum angular momentum with your push. Then when they pull arms and legs in to the center, the speed of the spin increases. It can create some very stunning effects.

When it comes time for a karateka to spin with back to the bad guy, you want to have your arms and your kicking knee tucked in close. This will get you around really fast so you can see your target quickly and not expose your own. Then at the last second you can extend your leg out again which allows you to hit the target and maybe even add more energy with the hamstring if it's a spinning hook.

It is true that it takes a fraction of a second to reorient when your spin your head fast. But most people don't need to read The New York Times when they do a spinning kick. If you more-or-less see the target, you are good to go. You can admire your work in greater detail after the bad guy drops.

- Bill

[Bill Glasheen]

Mike

Study this picture, and you see some of the principles I talked about above. This is future hall-of-famer Greg Maddux, who as an "old fart" on the day of this picture (Sunday, August 13, 2006) threw 8 innings of no-run, 2-hit ball. The Dodgers subsequently won 1-0 against the Giants in the bottom of the 10th

• Note that he has just finished heaving his body both forward and around. The "jumping" foot here is the right leg he drives off of. It is effectively done. He is now delivering both translational (down the mound) and rotational (towards his left) energy.
• Look at the arm holding the ball. It has yet to do anything. What you see here is the point of maximum stored (potential) energy in his biological torsion (twist) spring. The spring in his trunk is even flexed like a truck leaf spring. Many muscles in his trunk and some in his arm now have rapidly lengthened. His torso is so stretched that it looks like a sail catching wind. The viscoelastic property of soft tissue (rubber-band-like property) is now causing them to "snap" back. And the neuromuscular mechanisms (dynamic stretch reflex) are now kicking into high gear.
• A fraction of a second before this shot, his navel was facing 90-degrees to his right, and both arms were straight out. Why? He's taking advantage of the conservation of angular momentum. By spreading his mass out like that, he was able to get a higher load against all his core muscles as they applied rotational energy. It's a bit like pressing middle finger against thumb before you allow it to fly to the palm to "snap." Then as he drive forward and is now letting "the wave" of energy go to his extremity where the ball is (sequential summation of movement), he's now starting to pull that glove into his chest. It will be right up against the chest when he begins to release the ball, where he will add a last bit of velocity and a touch of spin with a final wrist flick. That shift of mass towards his spinning center maximizes the velocity of his throwing hand.

All the principles you need to know are applied here, albeit in a different venue.

- Bill

[miked]

Bill,

Your explanations and examples are quite helpful!

Thanks for taking the time to write in an understandable yet scientific manner.

All the besst,

Mike D.