Aikido Sensei
Of course, in aikido training the actual aikido techniqe is done by tori, the defender (also callednage), while the attack of the uke is merely a service so that tori can train. Therefore, it is quite common in aikido training that both partners focus almost completely on the tori role, and neglect that of the uke. It can go so far as to a state very near sleep, when an attack is done, as if this is a moment for rest, until again it is time to be tori.
Such a way of training is unfortunate in so many ways. Mainly, one's focus soon becomes blurred also in the tori role, and without increasingly advanced attacks it is impossible to advance in one's aikido. We need to be more skilled as attackers, to be able to teach ourselves and each other higher skills in the defense.
I do not primarily mean the self defense aspect, but the way (do) of aikido. When attacks get more precise, focused and sophisticated, then they stimulate the refinement of one's aikido, and one's understanding of its nature. When you show just as much care about your uke role, as you do about your tori role, then it will truly be aikido.
It's more fun, too, if you devote yourself to be uke, an attacker with the attacker's mind and strategy, when your partner is tori - and then switch to tori mind when it's your turn to do aikido techniques. The shift of behavior is good mental training, indeed, sort of instant acting: immediately switching from one role to its opposite. You'll have twice the fun.
Below, I present the most common attack techniques (kogeki or kogekiho) in aikido, and say something about what I try to think about when training them. I don't try to be complete. For example, kicks and some rare and odd grips are missing, as well as armed attacks. I may add them later. What is included, though, I hope you find of some interest.
In the photos, I do the attacks, and Tomas Ohlsson at my dojo Enighet in Malmö, is the tori.
You find an edited and expanded version of all this in my book Attacks in Aikido.
Attacks
Ai hanmi relation
KOGEKI. Attacks in aikido.
The aihanmi relation is when both persons have the same foot and arm forward. This is the traditional and typical guard between two adversaries in almost any martial art. Most right-handed persons want to stand with their left leg and arm forward, in unarmed combat. In the sword arts, though, it is usually the right side forward.
Aihanmi katatedori
Aihanmi katatedori is a right hand grip of tori's right wrist, or a left hand grip of tori's left. In the basic form, the same hand and foot should be forward in the stance of both tori and uke.
You get the best posture and relation to the partner if you compare it to the chudan kamae sword guard. Extend your hand from your center (tanden), not to the side, and face tori straight on. Think of it as an initial attack, fully alert, which can easily be followed up by other attacks.
It is very important not to think of it as only a grip of tori's wrist, but as a connection to control his or her whole body. You grip the arm, but you focus on tori's whole body, in particular his or her center. There should be a rather straight line from your center, through the grip and to tori's center.
Your grip on tori's wrist should also be very similar to that on a sword: the upward angle between your hand and arm, the back of your hand up and your fingers below. Some people grip from the side, which is weaker and less of a protection, since tori can easier move his or her arm up, toward your face. You should not press down, but hold so that the most difficult direction for tori to move the arm is upward.
Again, the grip is like on a sword when it comes to the roles of the fingers. Concentrate on gripping with your little finger, and don't worry about the rest. This way, your grip will be better anchored in your center. If you grip with the most force in your index finger, your shoulder will stiffen and you will lose the connection between your center and your grip.
A good way of describing the ideal grip on a wrist (as well as on a sword) is to think that the little finger is leading the wrist into the palm of your hand. When your palm is tightly connected to the wrist, so to speak air tight, your control of tori through the grip is optimal.
This attack form is unreasonably neglected in many aikido dojos. It may seem almost awkward as a grip, compared to gyakuhanmi, but the aihanmi relation is by far the most common between the adversaries in any other Martial art. With the grip you have a clear and concrete way of getting familiar with this relation.
You may also be surprised by how practical it can be as an attack. For example, when the adversaries stand in karate or boxing style guards against each other, one can quite easily snap the opponent's wrist, which is a good way of penetrating the opponent's guard.
Shomenuchi
Shomenuchi is a strike to the top of tori's head, with the ridge of the hand. It is done as a symbol of a sword attack, where the hand is tegatana (hand sword) with the hand ridge as the sword's edge. The relation to tori is of aihanmi nature, so that both have the right or the left foot forward, in the basic form. Also, uke has the same foot forward as the striking hand.
In the shomenuchi strike, it is recommendable to hold the other hand slightly behind the striking one, so as to resemble the two-hand swordgrip. This also helps you to remain centered through the attack. The strike should be done with the whole arm, in the unbendable arm extension, and not just the forearm - again, to resemble the sword cut.
Lift the hand to above your head, like the jodan kamae position with the sword, before the strike, but don't do that before advancing toward tori. To advance in a jodan kamae position gives less protection than to do so in chudan kamae (in front of your center). You raise the hand at the end of your final step toward tori, so that the strike follows almost immediately.
Don't relax the striking hand, but stiffen it - especially the little finger, so that the hand ridge muscle hardens. Otherwise the hand is quite fragile in such a strike. Remeber also to approach to actual striking distance. Tori cannot learn timing and distance properly, if the strike is done too far away, where it would not reach tori even if he or she remained at the spot.
I have noticed that many aikidoka shift front hand in their shomenuchi attack, so that they start with one hand in front but do the strike with the other. This is simply not possible when you hold a sword - you would just strike yourself with it (try it, if you don't believe me). Therefore, I strongly recommend that you keep the same hand forward through the attack. If you begin with your right hand forward, then that is the hand you strike with.
Of course, the shomenuchi attack has no meaning when done with an unarmed hand. The head is hard, especially at the forehead, so there are not many tegatana that can hit it without more damage being done to the hand than to tori's head. This is simply a way of training aikido against the sword attack, or any other armed attack to the head from above, in a safe way.
Shomenate is a strike to the front of tori's head, with the ridge of the hand. It is done as a symbol of a sword or knife forward strike (tsuki). The relation to tori is of aihanmi nature, so that both have the right or the left foot forward, in the basic form. Also, uke has the same foot forward as the striking hand.
In this attack (just like with shomen), it is recommendable to hold the other hand slightly behind the striking one, so as to resemble the two-hand swordgrip. Begin from chudan kamae, in front of your center, and thrust the hand forward and upward, to tori's face.
This is not really a basic attack form in aikido, but it is anyway used quite frequently in training - often as a substitute for shomenuchi, which is unfortunate, since the two attacks cannot always be treated the same way by tori. It is also frequently used by tori as an atemi technique. For example, some practice shomenate so that tori initiates by a shomenate toward uke, who blocks with the same movement. Tori then does the technique on uke's blocking arm. I am not too fond of that, since it comes very near to making tori an attacker.
Make sure to stiffen the hand, just like with shomenuchi, and make sure that you advance so that you reach an actual striking distance. Use the idea of the unbendable arm to make the attack strong.
Unlike shomenuchi, this attack is meaningful even when done unarmed. You only need to change the form of the hand to make it a very effective attack indeed. No need to get into detail about that here, you're sure to figure it out.
Tsuki
Tsuki is a fist strike either to the face (jodan tsuki) or to the solar plexus (chudan tsuki). It needs to be trained substantially, to be a good attack for tori to work on with aikido techniques. Much more can be said about it, than what is room for here. In karatedo the constant training of tsuki can be compared to the training of the basic cut in the sword arts. It takes time to learn well.
A few pointers: The power of the strike is in the acceleration of it, which is reached by relaxing in the movement, to harden your fist and arm only at impact. The direction of the strike must be straight, and end so that the fist is directly in front of your center. This means that you need to angle your body a bit, but not much, so that the side of your body with the striking arm is slightly more forward than the other. This body turn is done so that it adds force to the strike.
Moreover, it is the index finger and middle finger knuckles that are aimed at the target, so that they hit first. Form the fist by most firmly closing your little finger - the other fingers are not as important - and make sure that the thumb is tightly connected to the fist, for its protection.
The fist is held in an angle that prevents it from bending on impact. In traditional karatedo, the fist rotates some 180° during the strike - from fingers up to fingers down. This increases stability and effect (somewhat like the spinning bullet from a gun). At full extension of the tsuki, there should be a 90° angle between the arm and the body, again for stability. The arm should not be completely stretched, since that can damage the elbow when you miss the target (and you should miss, if tori is doing taisabaki properly).
Remember to advance so that the tsuki would really reach tori properly, if he or she were to stay on the spot (see the picture above). Otherwise, tori has no chance of learning the right timing and distance. When you advance, don't strike until you have reached tori, that is at the end of your last step.
There are two basic forms of tsuki in karatedo, depending on the foot position compared to that of the striking arm. To the left here isoitsuki, where the foot forward is the same as the striking arm. This is most common in aikido - in some dojos no other tsuki is ever trained. Surely, this is because the arm and foot relation here is the same as in the most common sword techniques and gripping techniques. In aikido it is rare to attack with one arm and the opposite foot forward, for reasons of balance and reach (and habit).
However, in karatedo the most appreciated tsuki is gyakutsuki, where the foot forward is the opposite from the striking arm. If you strike with your right arm, then the left foot is forward, and vice versa, like the picture to the right here. The gyakutsuki is very practical and popular in kumite, karate contest, because by this you can approach the opponent slightly to the side and thereby avoid his or her attack.
I think that the aikidoka should practice gyakutsuki as well as oitsuki, because it's there - and also because uke ends up in a slightly different position depending on what tsuki is used. This is particularly evident with the feet. Some aikido techniques take for granted that the same arm and leg are forward, and can become awkward when this is not the case. That needs to be experienced.
Attacks
Gyaku hanmi relation
GYAKUHANMI RELATION
The gyakuhanmi relation is when the two opponents have differing arms and legs forward, such as the left on one and the right on the other. This can happen when a left-handed person meets a right-handed one, which is particularly awkward for right-handed persons, since they are in a vast majority. In a gripping attack, though, it is the most common relation.Gyakuhanmi katatedori is when uke grabs tori's nearest grip, so that the right hand grabs the left wrist, or the left hand grabs the right wrist. In the basic form, their foot positions are the same - when uke grabs with the right hand, his or her right foot is forward, and so is tori's left foot - as opposed to what is the case in aihanmi katatedori.
This grip is the most common in aikido - so much so that it is usually just called katatedori (gyakuhanmi taken for granted). Indeed, it is the most convenient way to grab an opponent's wrist, but the gyakuhanmi relation between the two is not that common in normal Martial arts guards, where the aihanmi relation is almost always the case. Therefore, I am not sure that gyakuhanmi should be allowed such a dominant role in training - they are both needed.
Anyway, regarding the grip itself, it should be done in very much the same way as aihanmi katatedori - the little finger being the most important one, the angle and position of the hand, the tight contact with the palm on tori's wrist, and so on. See the text on aihanmi katatedori, above.
The difference from aihanmi katatedori is that gyakuhanmi is by necessity off center. Both for uke and tori, the grip is to the side of the body, not straight in front of it. Still, it is necessary to feel the connection with the center, and not to regard the grip as something applied from the shoulder down. Also, uke should apply the grip as an initial and not a final attack, that means alertness and a continued focus on tori.
An important key to understanding the gyakuhanmi relation as well as its katatedori application, lies in carefully considering the potential of the free hand - of both uke and tori. If this is neglected, the attack is of little value.
Ryotedori
Ryotedori is when uke grabs both of tori's wrists. It can simply be described as a double gyakuhanmi, and what goes for the latter applies also here. Since ryotedori is connected to gyakuhanmi, in the basic form the stance of uke and tori should relate in the same way - that is, if one has left foot forward, the other should have right foot forward, and vice versa.
An interesting aspect of ryotedori, and other two-hand grips on both sides of tori, is the deviation from a single line connection with the center. Here, both uke and tori are so to say split, in regard to their center. Uke must still feel his grips as extensions of power from the center, and still regard the grips as a means to contact with and control over tori's center.
Because of this "split from the center", I would say that ryotedori relates more to jo (the staff) than to ken(the sword). With the staff, the hands are usually separated, and should be able to move freely up and down the full length of the staff - one should still be able to maintain one's center, and to fetch the source of each movement from there.
For the training of awareness of both uke and tori, it is also good to carefully consider the potential of the legs in this position. The arms are locked in the grips, but the legs are not.
Katadori
Katadori is a grip in tori's keikogi (training jacket) by the shoulder. Uke should have the same foot forward as the hand gripping tori. The stance is a gyakuhanmi relation, which means that if uke stands with left foot forward, then tori has right foot forward, and vice versa.
When you grab tori's dress, make sure that it is done mostly with your little finger, which anchors the grip in your center and makes you more flexible than if done with your power in the index finger. Don't let your thumb get too nestled into the cloth of tori's jacket. Actually, you should be careful about all your fingers, since some aikido techniques really tie them into tori's jacket in a way that might harm them during the technique.
Some aikidoka tend to grip on top of the shoulder, instead of to the side of it. This is rather meaningless, since it is very difficult to control tori that way. The grip should limit tori's ability to use the arm, which is not accomplished at all with a top shoulder grip. Try both ways out, and you see what I mean.
Of course, the grip should be done in the spirit of being an initial attack, with a readiness to continue with other attack forms (like in katadori menuchi, below).
Ryokatadori is when uke grips tori's jacket by both the shoulders, simply a double katadori. The stance is a gyakuhanmi relation, which means that if uke stands with left foot forward, then tori has right foot forward, and vice versa.
Do the grabbing in the same way as described above about katadori - with the little finger, careful not to get your fingers too much nestled into the cloth of tori's jacket, and by the sides of the shoulders instead of on top of them. In this position you really need to be able to control tori's arms to some extent, since both of your own arms are locked in the grip you applied.
The grip should be done in the spirit of being an initial attack, with a readiness to continue with other attack forms (with the legs, or by pulling or pushing tori). Actually, it is not a very practical attack at all, if not some continued attack is intended.
Notice that this attack needs you to face tori straight on, to have a good control, so avoid anyhanmi kamae turn of your body (hanmi kamae is when you stand with one side of your body slightly more forward than the other). Notice also that this is an attack form which is a bit awkward to apply if tori stands in an accentuated hanmi kamae. Therefore, it makes the most sense if tori, too, stands straight forward.
Munedori
Munedori (sometimes spelled munadori) is when uke grips tori's jacket by the front, right on the chest. Because of its similarity with katadori, the stance is a gyakuhanmi relation, which means that if uke stands with left foot forward, then tori has right foot forward, and vice versa. Of course, uke should stand with the same foot forward as the hand doing the grip.
Do the grabbing in the same way as described above about katadori - with the little finger, careful not to get your fingers too much nestled into the cloth of tori's jacket. Your hand should be positioned so that your little finger is down and your thumb up, which keeps a good link to your center and your elbow down. When your elbow is down, tori will have the most difficulty in applying a technique on your arm.
Also, try to apply the grip directly with just one hand - don't start by adjusting the collar of tori's jacket with the other hand. If you do, then tori should really act on the first hand coming, not wait for the next one.
The grip should be done in the spirit of being an initial attack, with a readiness to continue with other attack forms. What makes this attack particularly interesting for tori is its firmness - correctly applied, this grip is not easy to get out of. An additional difficulty is the fact that tori doesn't have too much room for applying an aikido technique, since uke is so close and blocking much of the space in front of tori.
This is an attack form which is a bit awkward to apply if tori stands in an accentuated hanmi kamae. Therefore, it makes the most sense if tori stands straight forward.
Sodedori
Sodedori is when uke grips tori's jacket by the end of the sleeve. It is closely related to gyakuhanmi katadori, so in the stance, if uke stands with left foot forward, then tori has right foot forward, and vice versa. Of course, uke should stand with the same foot forward as the hand doing the grip.
Do the grip mainly with the little finger, and with the same angle of the hand as in katatedori.
The grip should be done in the spirit of being an initial attack, with a readiness to continue with other attack forms. It is not a very interesting attack form, except for its lack of physical contact body to body, which makes it a little more difficult for tori to gain control of uke, than in katatedori. Usually, this grip is mostly trained in the double form, ryosodedori. Still, it's not one of the major attack forms in aikido.
Ryosodedori
Ryosodedori is when uke grips tori's jacket by the end of both the sleeves. It is closely related to ryotedori (and to sodedori, of course), so in the stance, if uke stands with left foot forward, then tori has right foot forward, and vice versa.
Do the grips mainly with the little finger, and with the same angle of the hand as in katatedori. Stand straight toward tori, not in a hanmi kamae angle, for better control. Also, if tori stands in too much of a hanmi kamae angle, this grip is awkward to apply for uke. Therefore, it's best if both stand straight toward each other.
The grips should be done in the spirit of being an initial attack, with a readiness to continue with other attack forms (with legs, pushing or pulling). It is not a very interesting attack form, except for its lack of physical contact body to body, which makes it a little more difficult for tori to gain control of uke, than in for example ryotedori. Usually, this grip is mostly trained in the double form, ryosodedori, and not in the single version sodedori. Still, it's not one of the major attack forms in aikido.
Ryohijidori
Ryohijidori is when uke grips both of tori's elbows. It is closely related to ryotedori and to ryosodedori. The stance is the same: if uke stands with left foot forward, then tori has right foot forward, and vice versa.
Grab around the elbows. Stand straight toward tori, not in a hanmi kamae angle, for better control. Also, if tori stands in too much of a hanmi kamae angle, this grip is awkward to apply for uke. Therefore, it's best if both stand straight toward each other.
The grips should be done in the spirit of blocking tori from attacking. It's not easy to control somebody's elbows, which are strong even on persons who are not very muscular. This grip is mostly trained in the double form, ryohijidori, and not in the single version hijidori. It is not one of the major attack forms in aikido.
Yokomenuchi
Yokomenuchi is when uke strikes at tori's temple with the ridge of the hand. The attack is related to shomenuchi, but here the stance has a gyakuhanmi relation, that is if uke has left foot forward, then tori has right foot forward, and vice versa. Uke should have the same foot forward as the hand that strikes.
Like shomenuchi, this is really a sword attack, but done with an unarmed hand. The hand in this form is called tegatana (hand sword). The angle of the strike is not horizontal, but diagonal - in kendo the difference between shomen and yokomen is not much at all.
Form and use your hand the same way as in shomenuchi, keeping it hardened especially at the hand ridge. Make sure to swing your whole arm in the strike, not just the forearm. Let your other hand follow a bit behind, to resemble the two-hand sword grip.
Don't allow yourself too much of a hanmi angle to your stand, although it's tempting as the attack is a bit from the side, but you lose a lot of power and sharpness in the strike if you do not face tori straight on.
There is an unarmed attack similar to yokomen, in karatedo. It is done with shuto, the hand ridge, in a circular horizontal strike. Usually, this technique is not the one intended in aikido, but the sword cut. Of course, it is possible to train both.
When you do the karatedo shuto technique, allow your elbow to extend to your side, so that you can swing the forearm forcefully in the horizontal strike - but when you do the sword form, it is not correct to open yourself up with your arm out to the side. Unfortunately, the latter is done by so many aikidoka, that they allow tori's defense technique to adapt to it - and be practically impossible if a correct sword style yokomen is done.
Katadori menuchi
Katadori menuchi is a combination of two attacks: katadori and shomenuchi. Uke grabs tori by the shoulder, and immediately follows up with a shomenuchi strike. Since the initial attack is katadori, the relation between uke and tori is that of gyakuhanmi, so that if one has the left foot forward, then the other has right foot forward. For how to apply the katadori grip and the shomenuchi strike, see the texts about those, above.
In most aikido dojos, the students are taught that tori should wait for the second attack, the shomenuchi. I am not really fond of that, since a basic principle of aikido should be to act on what comes first. It is far better for tori to treat the attack as a katadori, and a correct initial taisabaki should result in the shomenuchi missing its target, anyway.
But that is of little concern to uke, of course. Uke should just make sure to do the attack so, that there is no pause between the katadori grip and the shomenuchi strike.
Katadori yokomenuchi
Katadori yokomenuchi is a combination of two attacks: katadori and yokomenuchi, very similar tokatadori menuchi above. Uke grabs tori by the shoulder, and immediately follows up with a yokomenuchi strike. Since the initial attack is katadori, the relation between uke and tori is that of gyakuhanmi, so that if one has the left foot forward, then the other has right foot forward. For how to apply the katadori grip and the yokomenuchi strike, see the texts about those, above.
This is not a very common attack form in aikido - usually the katadori menuchi is used, with a shomen strike, and rarely a yokomen strike. The yokomen is a bit more awkward to do, since it is to the other side of tori, from where the katadori grip is applied. In the sword arts, though, there is actually little difference between shomen and yokomen, so where one is easy to to do, the other should be almost as easy.
Just like with katadori menuchi, most aikido students are taught that tori should wait for the second attack, the shomenuchi. I prefer to act directly on the first attack, the katadori. Anyway, uke should make sure to do the attack so, that there is no pause between the katadori grip and the yokomenuchi strike.
Of course, it is also possible to combine katadori with other follow-up attacks, for example jodan tsuki, a fist punch to the head. That is not a basic attack form in aikido, but worth trying anyway.
Kata katatedori
Kata katatedori is a combination of two attacks: katadori and katatedori. Uke grabs tori by the wrist and the shoulder, either simultaneously or in very quick succession. Usually this is done with the same foot forward as the hand that applies the katadori grip, since it is otherwise difficult to reach the shoulder. Because of this, the relation between uke and tori is gyakuhanmi - that is, if one has left foot forward, the other has right foot forward.
For how to apply the katadori and the katatedori grip, see the texts about those, above. Notice that the katatedori grip is like aihanmi, but the stance is like gyakuhanmi.
This is a rare attack form in aikido - I have not even found it in a Google search (maybe another name is used for it, than kata katatedori). It is not very practical if uke is alone in doing it, since both arms will be locked, while tori has one arm free. Infutari (two attackers), though, it is a practical holding technique, if done on both arms of tori.
Attacks
Ushiro relation
The ushiro relation is when the attacker comes from behind, or goes to the rear of the defender. In training, it is usually done so that uke starts from the front of tori, and steps behind him or her - often after initially grabbing one wrist or shoulder, as explained below.
Morotedori
Morotedori (also called katate ryotedori) is when uke grabs one of tori's arms with both of his or her hands. Normally, it is not regarded as an ushiro form, and many aikidoka simply grab the arm in front of tori - but I see little meaning in such an attack form. Uke locks both of his or her arms, but only one of tori's, and still stands right in the way of tori. Not wise.
I prefer it when uke grabs the arm and immediately steps behind tori, to the position showed on the photo above. There, uke is reasonably protected from tori countermeasures. Also, with such a grip on tori's arm, uke can quite easily block tori from spinning around.
If the attack starts from the front, uke begins by grabbing tori's wrist in aihanmi style (right hand grabs right wrist, or left hand grabs left wrist). Immediately after that - preferably in a flowing movement - uke steps behind tori and applies the other hand.
The morotedori grip is similar to that used in theyonkyo aikido technique. Actually, uke can increase the control of tori by applying yonkyo, if tori tries to spin around to that side. If tori tries to spin around to the other side, uke can stop that by moving tori's arm in that direction. If tori tries to kick, uke can block it my moving the arm down. Correctly applied, this is quite a good control grip.
Observe that, because of the position of tori's arm and uke's hands on it, aikido techniques need to be done a bit differently from if uke grabs the arm straight in front of tori.
Just like with any grip, it is important for uke to focus on the little fingers, and to have the sword grip style upward angle on the hands. Read more about the grip on aihanmi katatedori, above.
To maximize power and control, it is also important for uke to have hands and feet in a correct position: when tori's right arm is grabbed, uke's left hand should have the highest grip (closest to tori's elbow), and uke's left foot should be in front. If tori's left arm is grabbed, then uke's right hand should grab above the left, and uke's right foot should be in front. This gives the best stability, and stops tori from easily lowering his or her elbow.
Finally, uke should keep his or her elbows tight to the body, and not extended. Again, this increases the power of the grip significantly.
Ushiro ryotedori
Ushiro ryotedori is when uke grabs both of tori's wrists from behind. Normally, this position is reached by uke first grabbing one of the wrists from the front, in aihanmi style (right hand grabs right wrist, or left hand grabs left wrist), and then stepping to tori's back to grab the other.
Because of the way uke moves to get behind tori, and the way tori moves in taisabaki steps while uke proceeds, they will end up with opposite feet forward - if uke has left foot forward, tori has right foot forward, and vice versa. See the photo above.
For example, if uke starts by grabbing tori's right wrist, then tori has right foot forward, and uke will round tori on tori's right side, to grab tori's left wrist from behind and stand with left foot forward. It seems complicated, but it's the most natural way of doing it, since uke will want to have the best balance for grabbing the second wrist, and that is accomplished by the foot on that side being forward.
Regarding how the hands should do their grips, see aihanmi katatedori above.
When uke has grabbed the first wrist, it is important to lower it, before going behind tori - or tori could easily hit uke with the elbow.
In aikido, ushiro is never trained with katatedori, gripping just one wrist, since that is a very impractical attack form. The idea with most ushiro atacks, is that uke controls tori from behind and tries to stop tori from turning around - with just katatedori that is virtually impossible.
For uke to try ushiro ryotedori, starting from in front of tori, tori's other arm must be reasonably available from the back. That is, tori has to let that arm drop to the side, or even hold it a bit backward, for uke at all to want to do ushiro ryotedori. If tori holds both of the hands in front of him or her, uke would be much more likely to grab ryotedori from the front, than to try for ushiro.
Ushiro ryokatadori
Ushiro ryokatadori is when uke grabs both of tori's shoulders from behind. Similar to ushiro ryotedoriabove, this position is usually reached by uke first grabbing one of the shoulders from the front, and then stepping to tori's back to grab the other.
The second shoulder is easier to find and grab from behind than the wrist, so here it is of little concern how tori positions him- or herself beforehand. Regarding the katadori shoulder grip itself, see katadori above.
In aikido there is no ushiro training of katadori, gripping just one of the shoulders from behind, since that is impractical - just as stated above aboutushiro katatedori (in the text about ushiro ryotedori).
Kubishime
Kubishime is when uke locks tori's neck from behind, which is almost always done toegther with a katatedori grip on tori's wrist. Therefore the attack is also called katatedori kubishime. Since it is from behind, the full name of the attack would be ushiro katatedori kubishime, but the ushiro is taken for granted, since kubishime is not done from the front in aikido.
If uke starts from the front, it begins with gripping one of tori's wrists, ai hanmi style (right hand grabs right wrist, or left hand grabs left wrist). Then, uke moves behind tori and applies the neck lock.
The neck lock can be done in a number of ways, for example with or without grabbing tori's collar. On the photo above, it is done with a grip on the collar. Uke will have the best balance and stability, if the same foot is forward as the arm applying the neck lock. Also, uke should not position him- or herself right behind tori, but a little to the side of the wrist grip. This way, it is more difficult for tori to reach uke with the free hand.
The reason for the katatedori grip is to lock one of tori's arms, so that tori has greater difficulty to counter the neck lock. Uke should strive to force tori back with the neck lock, so that tori stands in a backward arch. For maximum stability in the katatedori grip, uke should press tori's wrist toward his or her hip. See the photo above.
Eridori
Eridori is when uke grabs tori's collar from behind. Therefore, the complete name would be ushiro eridori, but the ushiro is taken for granted. To reach the back of the collar from the front, uke would have to be in a judo type clinch with tori - and then, surely, there must have been a preceding attack form for tori to act upon.
Since the back of the collar is so difficult to reach from the front, even if uke starts by moving around toward tori's back, this might as well be trained by uke initially standing behind tori.
For the best stability, uke should stand with the same hand and foot forward. Normally, but not necessarily, tori and uke will stand with the same foot forward. As with any grip, most of the power should be in the little finger, and the elbow should be pointing downward.
Eridori is not a tremendously practical attack technique, but it is trained in aikido because it creates some complications for tori in doing the usual aikido techniques.
Kakaedori
Kakaedori is when uke grabs tori's body from behind. The complete name would be ushiro kakaedori, but the technique is rarely trained from the front in aikido, so the ushiro is taken for granted. In wrestling, grabbing the opponent from the front is common, so it could be interesting to practice in aikido. I guess that it is not done, because normally in aikido, one should act before uke gets near enough to apply the grip.
This also means that the attack is regarded as a surprise from behind, so it might as well be trained with uke initially standing behind tori, instead of uke beginning in front of tori and moving to behind him or her.
There are two ways of doing kakaedori. The most common one in aikido, is where uke grabs around tori's arms, too, as on the photo above. The other one is when uke grabs inside tori's arms, that is just the body. This is shown in the photo below. I have never heard that they have separate names - I guess mostly the first one is taken for granted. I recommend aikidoka to practice both forms, since they lead to quite different solutions for the aikido techniques.
For the best stability, uke should stand with one foot back, not with feet together. The hands clasp in front of tori, at about solar plexus height, pressing him or her tightly toward uke. The clasp of hands can be done in many different ways, such as one hand grabbing the other by the ridge or the wrist, or the fingers of both hands hooking. It makes little difference.
When doing the first form of kakaedori, apply it approximately at elbow height of tori's arms. If higher, it is too easy for tori to sneak under the grip, and if lower, too easy to get the arms out upward. With the second form of kakaedori, that has no significance, but you may want to apply it on tori's chest, not lower, otherwise he or she can turn around rather easily.
Ushiro ryosodedori
Ushiro ryosodedori is when uke grabs both tori's sleeves from behind. Similar to ushiro ryotedori, it usually starts from the front, so that uke grabs one of the sleeves and then moves behind tori for the other one. Also the steps are done in the same way as for ushiro ryotedori, as well as how the foot positions of uke and tori are.
This attack form is not done much in aikido, although it belongs to the curriculum. As mentioned about sodedori above, it is mainly of interest because of its lack of contact between uke and tori, compared to for example ryotedori.
In ushiro, sodedori is never practiced with a grip on just one sleeve, since that is an impractical attack form. It is always both sleeves. Regarding the actual sleeve grip, see the text about sodedori, above.
I would say that ushiro ryosodedori is the most interesting sodedori attack form to train in aikido. Tori will find it more tricky to do the aikido techniques, compared to ushiro ryotedori, and uke will find that gripping both sleeves actually makes for good control of tori.
Ushiro ryohijidori
Ushiro ryohijidori is when uke grabs both tori's elbows from behind. Similar to ushiro ryotedori, it usually starts from the front, so that uke grabs one of the elbows and then moves behind tori for the other one. Also the steps are done in the same way as for ushiro ryotedori, as well as how the foot positions of uke and tori are.
This attack form is rarely done in aikido. In ushiro, hijidori is never practiced with a grip on just one elbow, since that is an impractical attack form. It is always both elbows. Grab the elbows firmly. It's not easy to hold on to elbows, since they are strong also on less muscular people.
The ushiro form of this attack is more interesting to train than its frontside version, since the grab makes more sense from behind for uke. Also, it is interesting for tori to make sort of "narrow" versions of the ushiro ryotedori techniques, because uke is much closer and grabs higher on tori's arms.