Judo Ron 41_ Power Associated With Movements_docx

Judo Discussion and Investigation of Selected Topics by Ronald Désormeaux

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Judo Ron 41. The power associated with movements in judo

In a previous essay called the “Discovery of Judo, Yield to overcome”, I made references to the

ten fundamental elements associated with Judo known as Kihons.

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Of these fundamentals, I

think that it is now opportune I undertake a quick review of some of the basic elements

contained in the principle of “Ju no RI “or flexibility. On that subject, the late professor Jigoro

Kano said in one of his early lectures that:”factors such as how best to apply a technique, what

one should avoid, how to attack in a given situation and to topple one’s opponent are skills

developed not only through one’s own training but by carefully observing the actions of

others…people with advanced skills of observation will progress quickly! “

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When we analyze the principles with the moving about on the tatamis, we discover that these

basic elements are associated with the natural posture and the light and swift movements of the

body as we adapt to changing situations. As such, we need to observe more carefully how we

perform the Shintai or posturing, the Tai sabaki or the art of placing the body at the right

distance and angle, the Tsukuri or the method of entry and the Kuzushi, the means to

accomplish the unbalance of the opponent devoiding him of the opportunity to take the

offensive.

Pursuing our goal to continuously strive to do our best in Shiai or Randori we need to sharpen

our intuitive senses and our power of observation. I would like to explore some observations

pertaining to the improved usage of natural power and to the increase of our efficiency as we

perform those essential elements to realize the maximum benefits with minimum efforts, thus

making intelligent use of our energy.

“The noble man seeks what he wants in himself; the inferior man seeks it from others.”

Confucius

“Judo is not a simple sport practiced by a majority; it is an art that is practiced by those who

observe, think, judge and act accordingly as a way of life”

Jigoro Kano

The judo tachi locomotion methods

When we embark upon a judo match, contest or Randori, we first evaluate the opponent and

the surroundings, make appropriate judgment as what constitute strength and a weakness and

then decide to act quickly to assume control or mastery of the situation. We thereafter begin to

adjust our posture to ensure the maintenance of our stability and to maximize our chances of

success and take advantage of the situation. In making the necessary adjustments, we make use

of the terms "Tsuri ashi" or “Ashioto” to describe the general and delicate suspended

footwork/footstep normally taken to move about.


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Judo is made up of all kinds of dynamic processes. If we wish to overcome the opponent, the

onus is upon us to maintain our equilibrium while placing the opponent in a weak state and take

the initiative. Let us use try to make greater use of our mind to dictate what actions we should

take. Seizing the right opportunity for an attack or a defense and continuously moving about to

profit from such a moment is in my view, the gist of judo. `

Realizing that both contestants can be placed off-balance (Kuzushi) by simply moving about, it is

important that we understand what causes our stability and how we can reinforce it or improve

both our balance and power of locomotion. We should be concerned with the placement of our

feet as anchors with the ground and the positioning of the arms in gripping the opponent

costume.

Our temporary stability is obtained when our body is properly and naturally aligned along the

gravity line which passes through the support base (the triangular position of the feet) in touch

with the mat. It is reinforced when we increase the dimension of the support base and when we

lower our centre of gravity such as when adopting Jigo-tai. Likewise, a soft grip on the Kumi-Kata

will permit more flexible responses while a hard seizure of the kimono will not only announce

our movement but may prevent us from a quick escape from potential danger.

Other means at our disposal to increase our stability is to make greater use of the increase

friction with the ground such as when walking in Tsugi-ashi method or moving about in a swift

and circular or spherical design (Tai-Sabaki) accompanied with increasing speed. As we increase

our rotational speed, we increase our velocity and make greater use of the natural power of the

body weight especially when the latter is combined with an appropriate torsion of the

abdomen.

We have to realize that whenever we change position, we influence the position of our centre of

gravity. Judo’s moving techniques have been refined to group the kinds of displacements into

several categories of maneuvers we use during the attack or defense, to entice or to apply a

counter-technique during the various phases of the engagement.

We normally have the on-line movements, which serve to advance with variable amplitudes

according to our objective and known as Ayumi-ashi and Tsugi-ashi. Then, we have some

systems to make side movements, of small or great amplitude, which serve essentially to evade

and are known as Sakeru or Yoko-ashi. Finally, we have the pivots, and rotational/spherical

maneuvers which allow us to quickly change directions of the entire body in all the angles and

known as Tai-Sabaki.

As most of us know, there are lots of opportunities to affect proper Kuzushi on the opponent

while engaged in a standing position. The general processes are known as Happo no Kuzushi or

using eight preferred directions. Of course, we can observe that there are infinite positions to

apply Kuzushi around a 360 degree surface. Notwithstanding, the possibility of applying mental

pressure to exercise a Kuzushi, the opponent can easily be destabilized when he places his body

weight disproportionately over one leg, cross over his feet, over stretch his reach, change his

gait or cadence, hesitate to move in a given direction and rest his body weight over a reduced

support base or on the outer edge of his feet. All of these instances can be transformed into the

right opportunity (Koki) to overcome the opponent.


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Ayumi-Ashi sequence

We can induce the opponent to adopt a vulnerable position by taking the initiative, thus forcing

him to react and move about. This is normally done by making use of proper Tsuri ashi and

Ashioto footwork/footstep we can choose either the Ayumi ashi / normal walk/ step or the Tsugi

ashi systems of shuffling/gliding towards the initial step with which we maintain both the

initiative and keep our own balance while enticing the opponent to make mistakes and be

overcome.

Tsugi-Ashi sequence

In addition, to these moving tactics or locomotion systems, I would like to share some

interesting findings which emanate from past and current research papers and from which we

can extrapolate some benefits towards improving our judo practice.

Impetus and momentum

Centuries ago, the French independent physicist Jean Buridan (1300-1356) who was a critique of

Aristotle’s physics observation began to examine scientifically the nature of “motion.” He

challenged the previous concept held about motion which stated that a body was only

maintained in motion by the action of a continuous external force, and that in the absence of a

proximate force, the body would come to rest almost immediately.

Jean Buridan proposed that motion was maintained by some property of the body, imparted

when it was set in motion. He named the motion-maintaining property "impetus." He rejected

the view that the impetus dissipated spontaneously, asserting instead that a body’s movement

would be arrested by the forces of air resistance and gravity opposing its impetus. Buridan

further held that the impetus of a body increased with the speed with which it was set in

motion, and with its quantity of matter. He saw impetus as "causing" the motion of an object.

Buridan’s theory preceded to some extent, the theory outlined by Sir Isaac Newton ( 1643-

1727)in his work the Principia Mathematica published in 1687 where he stated his three

universal laws of motion. As we shall see, the understanding of these laws is paramount in judo.


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Lets us review the Newton’s concepts pertaining to motion, gravity and acceleration.

Newton's First Law states that an object at rest tends to stay at rest and that an object in

uniform motion tends to stay in uniform motion unless acted upon by a distinct external force.

Newton's Second Law states that an applied force on an object equals the rate of change of its

momentum, with time.

As with Buriden’s theory, the first and second laws of Newton represent a break with the

Aristotle’s concept in which it was believed that a force was necessary in order to maintain

motion. The new concepts now reaffirm that a force is only needed in order to change an

object's state of motion and need not be applied constantly.

Newton's Third Law states that for every action there is an equal and opposite reaction. This

means that any force exerted upon an object has a counterpart force that is exerted in the

opposite direction back onto the first object. Since the objects in question do not necessarily

have the same mass, the resulting acceleration of the two objects can therefore be different.

In the case of human movement, the force needed to make a change in position or stability can

come from within (produce by the nervous system in collaboration with muscles and the joints

structures) as well as from an external force being applied against us.

Recent biomechanics research papers presented by Dr Attilio Sacripanti

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and others have made

good use of this past universal knowledge and concentrated their efforts upon particular issues

which may help us to better understand the mechanics in the various motions of a judoka.

Energy generation and absorption

Several researches conducted within academic and sports-related establishments illustrated the

distribution of energy and the degree of stress absorption during different walking patterns of

humans. It is understood that the human’s displacement force is the force that can be applied to

an external environment through the body’s working points (joints) or contact points with the

external entity thus producing linear or kinesthetic momentum and energy (translation and

rotation motions). We are somewhat more familiar with the force of the arms and forearms as

used in the Kumi kata and the power of the legs when moving about. Such force or energy is the

resultant of some coordinated actions or systems of leverage emanating from the contraction or

extension of some 200 joints involving over 1000 muscles and tendons.

The human machine that we are is mainly dependent upon our muscular and skeleton systems.

Everyone of our motion comes from the cooperation between three muscular functions:

eccentric, isometric and concentric.


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In other words, we have the muscles contraction that fights against resistance and start a

motion in a given direction; the muscles that balance and break the agonistic action and provide

the speed of motion; and the fixing muscles that guarantee the bones stabilization giving it the

right fixedness for the motion. It is important to realize that the power of each muscle will vary

depending on the relationship between those three components: length, velocity and time

relative to activation (impulse).

In his biomechanical thesis, Dr Sacripanti gives the following opinion about muscle

coordination:”Normally the agonistic contraction gives the motion direction while the

antagonistic gives the speed, but in determined complex motion like judo throws, the muscles

function could change with time. This role interchange is due by the reason that it is not possible

to obtain a perfect balance of contractions with every muscle group, unless one is embarking

into a long and constant conditioning and training regime.”

We also know from observing the actions-reactions occurring in Kansetsu Waza (arm locks) that

there are joints restricted in their motion to one plane such as the flexion-extension of the

elbow. Yet, this joint is very powerful if the muscles group and the alignment of the angle are

properly used in sequence to push, pull of lift. Other joints are capable of more freedom such as

the knee joint performing limited rotation and flexion-extension actions to displace the body in

various directions. There are also some joints that can move in multiple planes such as the wrist

and ankle joints which can absorb, rotate, twist, lift and push etc.

To that effect, I recall reading an article in the Journal of Clinical Orthopedics in 1983 which

pertained to the actions produced at the ankle and knee regions. It indicated that during slow

natural and fast cadences, the ankle area produces two mechanical power phases: first, a

negative work phase occurring during the body weight acceptance (action) and followed by a

positive work phase expressed through a dominant burst produced (reaction) during the push-

off period. It seems that we normally accept these phenomena and that this muscle reflex of

action-reaction is not consciously practice in the preparation of a technique.

The sequences occurring at the knee level is reported to be more complicated in that four

power phases were observed : a negative work phase at the time of weight acceptance, a small

positive work phase during mid-stance, a major negative work burst during push-off and early

swing, and a final energy absorbing phase at the end of the swing. This observation reaffirms the

need to walk with slightly bent knees (similar to a skater) in order to maximize the positive work

phases taken place at that joint level and thus complementing the dominant and positive work

burst occurring at the ankle zone which is propel by the plantar flexors muscles. It is also

important to move quickly and swiftly as the energy absorption by the quadriceps muscles

around the knee joint and during the weight acceptance phase seemed to decrease more

rapidly both when the speed decreases and during the late stance period.


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It seems that the angles of action by the joint determine the degree of freedom, the power level

and the kind of motion to be expected. At zero angles, there is no motion expected since the

system is totally balanced. The energy distribution appears to be changing with the demand

caused by the variation of the angle of push. The retention of a flexible stance and the

placement of the foot-leg combination at the right angle must be considered more frequently

when entertaining a throw in judo.

The activators of the ankle, drawings by Giovanni Civardi in Drawing Human Anatomy, 2003

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The study reported that the energy absorption by the ankle plantar flexors muscles during

weight acceptance remains fairly constant at all walking speeds while the absorption by the

knee flexors during the end-swing drops slightly as cadence decreased.

We can make use of these observations in teaching the importance of the foot placement on

the mat and the role of the toes for both maintaining equilibrium and propelling the body

upwards when doing the Tsukuri phase of the throw. Consequently, if we can jump-start at the

right time in order to profit from the maximum natural power of our lower extremities we will

gain from the augmented power and execute better Kuzushi.

Displacement preferences and adaptations

In judo, we sometime associate the judoka’s efficiency with his or her release of energy from a

quick burst, the speed of movement and endurance displayed during the short period of

engagement (less than five minutes, a normal time period for a contest bout). I identified similar

situations reported by several researchers involved in the areas of sports and physical education

such as Krzysztof Maćkała and Ryszard Michalski whose work was reported in 2010 in volume 25

of the Journal of Human Kinetics. These researchers conducted some analysis about the

importance of asymmetry in step length with regards to the deployed leg strength used by short

distance runners involved in the 200 meters dash. That study is akin to judo activities in that,

both the judoka and the runner need a combination of excellent departure power, high level of

speed endurance over a short duration and some technique or strategy to adequately cope with

an external force.


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The researchers found that the choice of a preferred leg expressed by differences in step length

during walking and running is probably occasioned by a natural selection. That selection being

made intuitively to prefer either the left or right leg will result in its use for the weight support

and body weight transfer during walking while the contra lateral limb contributes more to the

body propulsion. They argued that the inside leg (the chosen one) is likely responsible for a

stronger take-off, (in judo, we can equate this to the support leg) and thereby a longer step,

thus contributing more to produce accrued forward propulsion.

Illustrations originated from Ju Jitsu-Jkl.ch

However, considering their limited data, the authors suggested that further investigation was

needed to ascertain the true relationship between the use of asymmetry and the speed of

movement. We can extrapolate some of their limited findings to declare that: the optimal step

will most likely depend on the subject’s standing height, leg length and explosiveness of his or

her muscular contractions, the speed of movement of the lower limb and the range of motion in

the main joints. There is enough evidence to suggest that the preferred choice of support or

departure leg is primarily determined by natural genetic. (Characteristics of the right or left

hand persons)

Not every judoka is at ease with performing on either side. In my view, there is no need to force

him to adopt one side over the other and make him act out of character or perform from a weak

base. There is enough evidence to conclude that once the judoka has made his choice, there are

sufficient natural motor-skills abilities to carry the motion forward. Should the support leg be in

need of reinforcement, it is suggested to reinforce the muscle group with special strength

exercises such as weight training, rope skipping, drills for jumping on one leg and practice uphill

running.

Muscle mechanical advantages and costs in energy

Another opinion about muscle advantages was expressed in 2004 by Andrew A. Biewener and

his team in a paper presented to the department of Organism Biology and Anatomy of the

University of Chicago entitled Muscular forces generated during locomotion. He demonstrated

that the effectiveness of our locomotion was dependent upon the speed, the gait, and our

physical size (mass) as a moving object as compared to other animals. He used inverse dynamics

based on a force plate and some kinematic recordings of humans as they walked and ran at

steady speeds.


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Biewener examined how chemical changes occurring in muscle affect the muscle force-

generating requirements. He noted that the muscular forces generated during locomotion are

depended upon

speed, gait and size. He also observed that there was a substantial decrease in

the knee extensor capabilities to produce effective mechanical advantage (EMA) when humans

changed their gait from a walk to a run. The speed of the displacement played an important part

in the balance of chemical changes occurring. With increasing speed, there was an 18% increase

in the hip extensor EMA accompanied by a 23% increase in ankle extensor EMA. He concluded

that changes in EMA during running are likely to contribute to the

higher metabolic cost of

transport during running than in walking. We can conclude that It is important to regulate our

speed of displacement in order to consume only the necessary energy to accomplish the task.

Abdominal energy

In another article called Judo Ron 22, we discussed the internal power emanating from the

abdomen region known as the Hara Gei. Dr Jigoro Kano the founder of judo mentioned its use

several times but had not clearly described it as a technique to add power. He left its

interpretation and discovery to those who persisted in their technical research. Avoiding a

repetition, we will simply restate the importance of its power as a result of the coordinated

action of the abdominal muscles and the displacement of internal organs being placed at the

junction of the two principal body masses, the lower and upper limbs. These two entities can

rotate one unto the other while being connected by the most powerful muscles of the body,

namely the abdominal rectus, external oblique and the great latissimus dorsi muscles.

Drawing from Giovanni Civardi in Drawing Human Anatomy


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Dr Sacripanti made references to anterior research on Hara Gei by the imminent Japanese

physiologists K. Harumitsu and K. Hirata and he reports the following: “In fact, the abdomen

plays a determinant part in the making of a throwing technique…as it allows to transform kinetic

energy of a motion of rotor-translation from the first chain-(pelvis-lower limbs) into potential

energy of elastic contraction using the abdomen to re-transform it into a kinetic rotational

energy within the second chain (trunk and upper limbs). The transfer of the energy through the

abdomen has to emerge in an optimal way to obtain maximum energy in the second chain. This

is possible only if the body of Tori is not still or stiff, but remains loose, elastic and make use of

the hips.”

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With proper use of the energy found in the abdominal region, we can accomplish a greater

economy of effort since the subsequent movements needed for a throw will be accomplished in

proper succession and will assist each other in the sharing of the workload to be accomplished.

We must therefore study attentively the various phases of Kuzushi, Tsukuri and Kake to take

advantage of these combined forces.

The examples given above pertaining to energy absorption and distribution, the preference of

using the right support leg, the displacement with stability and the use of the abdomen region

should be exploited and repeated if we wish to improve our motion power in Judo.

Lessons learned

From the above, we understand that there are resources to be tapped to produce added power.

When we seek more dynamic plays, we require searching for ways to increase our impetus and

speed by measuring the length of our stride, the frequency of steps taken and seeking the

shortest distance to attack or enter into a defense. For added vertical power, we need to flex

the knee at the right angle and exercise more push on the ground with the toes. To maximize

the use of natural power, we have to identify how and when to apply the force of the abdomen

region. Now is the time to experiment, to ask more questions to our respected Sensei and to

seek continued ways to make improvements.

Ronald Désormeaux

Technical Director, Chikara Dojo

November, 2011

i

Ronald Désormeaux, The Discovery of Judo, ISBN-2-9806269-0-2, Canada, September, 2006

ii

Alex Bennett, Jigoro Kano and the Kodokan , Bunkasha International Corporation, 2009, page 12

iii

Attilio Sacripanti, Advances in Judo Biomechanics Research, VDM Verlag, Saarbrücken, Germany, 2010

iv

Giovanni Civardi, Drawing Human Anatomy , Cassell Illustrated, Octopus Publishing, 2003

v

Attilio Sacripanti, Advances in Judo Biomechanics Research, page 58-59

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Judo Ron 41_ Power Associated With Movements_docx