Slapping the mat in Judo
R.Devor
In judo, one is told to "slap the mat" at the moment of impact when one
has been thrown. How does it work? The effect is partly
pscychological, but I know that for the most part it is real. I was
always hurt when I missed the slap or when my timing was off. When I
slapped the mat properly, my discomfort was only mild.
Andrew C. Plotkin
Conservation of momentum. If you throw your arms down, you throw the
rest of your body up, reducing the speed of your fall. Your palms are
nice and large and padded, so it's much more confortable to take the
impact there. As opposed to, you know, your collarbone or something.
--Z
"And Aholibamah bare Jeush, and Jaalam, and Korah: these were the borogoves..."
Vincent Mulhollon
R.Devor (pros...@flash.net) wrote:
: In judo, one is told to "slap the mat" at the moment of impact when one
: pscychological, but I know that for the most part it is real. I was
: always hurt when I missed the slap or when my timing was off. When I
: slapped the mat properly, my discomfort was only mild.
Depending upon how much of a weightlifter you are, your arms probably
weigh about 30 pounds. So, when you throw your arms downward, you
accelerate your body upward, which lowers your the speed of your
landing a little bit.
It doesn't (in one sense) matter if your arms hit the mat or not.
Your using the recoil (newtons third law, etc) of throwing your
arms, the slapping your arms on the map is just what happens later.
With conservation of energy and stuff, realize that you're just
moving the damage from your back, butt and head to your arms.
Your arms are designed to take alot more punishment than your
neck, etc, so thats why you "aren't hurt"
I'll bet you get bruises on your arms once in a while though.
--
Vince Mulhollon N9NFB
Paul A. Delaney
"R.Devor" <pros...@flash.net> wrote:
>In judo, one is told to "slap the mat" at the moment of impact when one
>has been thrown. How does it work? The effect is partly
>pscychological, but I know that for the most part it is real. I was
>always hurt when I missed the slap or when my timing was off. When I
>slapped the mat properly, my discomfort was only mild.
>pros...@flash.net
I was told the same for karate. Slapping just ensures that most of
the force from the floor breaking your falls occurs on your hand, and
much of the shock is absorbed by the time it reaches your shoulder.
Something also about it's effect on your body's rotation as well.
Read a paragraph about it somewhere, I'll post tomorrow.
----------------------------------------------------------------
Paul A. Delaney, Biomedical Physicist (Anesthesiology)
U of MD Medical Systems and Medical School
R Adams Cowley Shock Trauma Center
Baltimore, Maryland 21201
Daniel W. Goodale
I'm not sure if is the same, but during "Combatives" in RANGER school, we
were taught to expose as much surface area to the ground as possible during
throws and take downs. Lots of bruises, but no broken bones. Distributing
force over large area saves bones.
Daniel Goodale (yes that is my real name)
Si
In article <31D89B...@flash.net>, "R.Devor" <pros...@flash.net>
writes
>In judo, one is told to "slap the mat" at the moment of impact when one
>has been thrown. How does it work? The effect is partly
>pscychological, but I know that for the most part it is real. I was
>always hurt when I missed the slap or when my timing was off. When I
>slapped the mat properly, my discomfort was only mild.
>
>pros...@flash.net
jump.
Dont know why though
See ya later Si.
Art Kotz
R.Devor wrote:
>
> In judo, one is told to "slap the mat" at the moment of impact when one
> has been thrown. How does it work? The effect is partly
> pscychological, but I know that for the most part it is real. I was
> always hurt when I missed the slap or when my timing was off. When I
> slapped the mat properly, my discomfort was only mild.
It is definitely real. Any momentum that you transfer to the mat by
slapping will not have to be transfered to the mat by your shoulder or
back...
If you slap too early, you will contact only with your hand, and you
could injure your hand, and you can't transfer as much momentum (small
contact area, long torque arm). If you slap too late ... well, you can
fingure that one out. If the slap is just right, you have a larger contact
area, and the momentum transfer is spread out over the length of the arm
and into the shoulder blade and side.
I remember the right *and* the wrong way well (ouch) -- not from Judo, but
from Akido and Hap Ki Do (Korean version).
--
Art Kotz <alk...@mmm.com>
"Narf!" - Pinky in "Pinky and the Brain"
Opinions expressed herein are my own and may not represent those of my employer.
Mark Tarka
In article <31D89B...@flash.net>, "R.Devor" <pros...@flash.net> writes:
>In judo, one is told to "slap the mat" at the moment of impact when one
>has been thrown. How does it work? The effect is partly
>pscychological, but I know that for the most part it is real. I was
>always hurt when I missed the slap or when my timing was off. When I
>slapped the mat properly, my discomfort was only mild.
>
Spread the pain.
Is this concept that difficult to understand?
SLAP THAT MAT, DANG IT!
Mark gmt...@msu.oscs.montana.edu msu-bozeman USA
M. T. McGeough
Si <si...@sico.demon.co.uk> wrote:
>In article <31D89B...@flash.net>, "R.Devor" <pros...@flash.net>
>writes
>>In judo, one is told to "slap the mat" at the moment of impact when one
>>pros...@flash.net
>Thge same principle is used when doing a roll at the end of a parachute
>jump.
>Dont know why though
>See ya later Si.
Could both of these methods work by prolonging the time of impact
(deceleration), thereby decreasing the forces involved and resulting in
less injury ? Sort of like using muscles as shock absorbers, in the judo
case, at least.
mtm
Jennifer O'Brien
I think you are on the right track, but everyone is missing one very
important element that might help explain what's happening. You don't
just slap the mat as hard as you can, you are supposed to let your
slapping hand relax and come up (recoil) after you hit. If the hand and
forearm don't come up, your whole body bounces and you know you've done
it wrong. It hurts. Most of the time it happens when the person is too
stiff or tense. My mental image is of the toy made of balls suspended
from strings -- the one where you drop a ball on one end and the ball on
the other end pops up.
Also, as other people have pointed out, it's important to spread the force
of the impact out over as much surface area as possible. The force is
spread over the entire side of one's body (slightly to the rear, but more
to the side), from the foot up to the armpit, then down the arm. The foot
on on the other leg will take some of the impact too. But you have to
time the slap so that everything hits at the same time. If the slap is
early or late, whatever hits first will hurt. After you've done it a few
hundred times, it's easy to time.
But the best falling technique won't absorb all the impact of a really
hard throw. That's why we practice on mats (like wrestling or gymnastics
mats). And of course if your mats are on a somewhat flexible subsurface,
all the better. Hardwood floors make a great substrait for judo mats.
Concrete sucks. The cushiest mats I've ever practiced on were on a wood
floor that had old tires under it.
--
Jennifer O'Brien
Reston Communications
Jim Carr
"R.Devor" <pros...@flash.net> writes:
}
} In judo, one is told to "slap the mat" at the moment of impact when one
} pscychological, but I know that for the most part it is real. I was
} always hurt when I missed the slap or when my timing was off. When I
} slapped the mat properly, my discomfort was only mild.
It is real, just as it is better to get the body to hit at the same
time rather than whiplashing one part down after another part hit first.
You are distributing the impact over a larger area so the local pressures
are less. I suspect you have to "slap" to get your arm to hit at least
as fast as your body is already going and to get the timing right.
Si <si...@sico.demon.co.uk> writes:
>
>Thge same principle is used when doing a roll at the end of a parachute
>jump.
This distributes the impact over small areas in a longer time, rather
than a larger area in a fixed time. This is feasible because you have
more control when landing a parachute jump than when being thrown by
an opponent. You have time to prepare for it.
I (snow) ski, and there it is almost always safer, with the exception
of some extreme places where falling can be fatal, to give it up and
take a nice even judo-style fall. All sorts of injuries, like ACL
tears or shoulder and wrist injuries come from fighting a fall.
My, all this sports stuff. Good thing Sunday is on tap for some
applied physics of tire adhesion under extreme turning forces.
--
James A. Carr <j...@scri.fsu.edu> | The Coca-Cola Olympic Flame passed
http://www.scri.fsu.edu/~jac/ | through Tallahassee on 2 July 1996.
Supercomputer Computations Res. Inst. | See a photo at http://ourworld.
Florida State, Tallahassee FL 32306 | compuserve.com/homepages/kcarr/
Michael Kowalik
Relaxed body will collide with the surface (mat) with maximum contact
area. Stiff body will expose shoulders, elboes etc. to point impact
pressure. The mat slap aims to accumulate as much as possible of the
fall energy into the palm of the hand and to discharge it during the
slap. The palm of the hand can take far stronger impact than other parts
of the body.
James Gillespie
Si <si...@sico.demon.co.uk> wrote:
>In article <31D89B...@flash.net>, "R.Devor" <pros...@flash.net>
>writes
>>In judo, one is told to "slap the mat" at the moment of impact when one
>>pros...@flash.net
>Thge same principle is used when doing a roll at the end of a
>See ya later Si.
Not when I learned to jump (eight years ago, round canopy): knees
and ankles together, hands on the steering toggles and arms in a
position to protect the face. Brace yourself and try to hold the
position until you've stopped moving. Feet should (!) hit first,
followed by calf, thigh, hip, side and a roll across the shoulders so
you end up lying on your other side. Works very well when you get it
right.
Jim
Jim Gillespie ,'_
j...@sbil.co.uk / -.--. ___ Calvin: "Cool people wear dark glasses!"
+44 171 721 2672 _~\ \__`--'_,-' Hobbes: "It's cool to bump into things?"
/ /\\ `--'_-\\
'94 ZZR600 \__/ `----' \__/
R.Devor
>OUCH!!!
>Thanks everyone for replying to the above observation.
I have seen no studies on the physics of judo, but the amount of e-mail and answers to
this question were both interesting and thought-stimulating.
I would have to agree with everyone re: increase the contact area of the body with the
floor at the moment of impact, thereby decreasing the impact force per unit area.
This decrease is especially desirable on the rib cage.
Paul Delaney even mentioned something about the body's rotation in order to lessen the
fall's force. I would also suggest that the slap may rotate the trunk of the body away
from the impact and further protect it (conservation of angular momentum).
All I know is that if you slap the floor as you fall it certainly hurts a lot less than
if you don't! I've been doing the sport since I was 10. Once during a practice
routine (age 16), I was having a tough time with one opponent. In my frustration I
wanted to take the fall without slapping the mat and be able to bounce back up ready to
defend myself. Only this time, I landed on my right side (no slap) and cracked a rib!
I've never forgotten to slap the mat since! FWIW
+++++++++++++++++++++++++++++++++++++++++++++++++++++
Lawrence R. Mead
R.Devor (pros...@flash.net) wrote:
: In judo, one is told to "slap the mat" at the moment of impact when one
: has been thrown. How does it work? The effect is partly
: always hurt when I missed the slap or when my timing was off. When I
: slapped the mat properly, my discomfort was only mild.
: pros...@flash.net
You are spreading out the stopping force of impact over a larger area - the
two hands (and muscles of course) combine to slow the body; the bodily
impact is thus less.
--
Lawrence R. Mead (lrm...@whale.st.usm.edu)
ESCHEW OBFUSCATION ! ESPOUSE ELUCIDATION !
http://www-dept.usm.edu/~scitech/phy/mead.html
Wulf Corbett
In article <4s0ath$2...@thorn.cc.usm.edu>, "Lawrence R. Mead"
<lrm...@ocean.st.usm.edu> writes
>R.Devor (pros...@flash.net) wrote:
>: In judo, one is told to "slap the mat" at the moment of impact when one
>: has been thrown. How does it work? The effect is partly
>: pscychological, but I know that for the most part it is real. I was
>: always hurt when I missed the slap or when my timing was off. When I
>: slapped the mat properly, my discomfort was only mild.
>:
>: pros...@flash.net
>
>You are spreading out the stopping force of impact over a larger area - the
>two hands (and muscles of course) combine to slow the body; the bodily
>impact is thus less.
>
and back, which can absorb the impact better.
--
Wulf Corbett