During a keiko Saito Hitohira sensei talked about Aikido training. He talked about being a good uke and what points you should remember...
"When we practice Aikido we should not be competitive. We shouldn’t try to hold our partner as hard as we possibly can. Everyone has a limit as to how much power they can deal with. If we are capable of holding our partner beyond their limit then this is not training, it becomes a competition. Aikido is not a martial art. It is Budo. The purpose is not only to make you physically stronger but also to make you mentally stronger. Aikido’s goals are achieved through keiko. By constantly testing and pushing your limits further and further. But, in order to push that limit we have to train at the limit. Not above it.
Think of how a bodybuilder gains muscle. On their first day in the gym they don’t pick up 30kg dumbbells and start doing bicep curls. This would be pointless. They would not be able to do one rep without swinging it up, using tons of momentum and completely wrecking their form. Aikido is the same. If we train beyond our limit we will wreck our form.
As a good uke you should try to hold our partner at the edge of their limit. Just at the point where they find it hard to move freely. If they cannot do the technique then lower your power level and find where their limit is. You are not a bad uke if you start above their limit. But you are a bad uke if you stay there when you know it is beyond them."
Sensei went on to say.....
"Good Aikido keiko is actually much harder to practice than that of competitive martial arts. In a competition based martial art we don’t know what technique our opponent will do. We are constantly trying to guess what they will do and counter it. It is easy to be an honest uke in Judo. If the throw is good you will be thrown, if the throw is bad you will not.
However in Aikido you already know where our partner will step or in which direction your partner will move or push. It is easy to counter them and regain your balance. But this is not keiko. You are basically escaping from the technique. If you continually try to escape your partner will have to continually change the technique in order to throw you. This is not keiko.
An uke should set their position at the start of a technique and try not to move from it. If their balance is broken then they should accept that and go. However do not intentionally turn your back on your partner. What we are doing is BUDO not martial arts. If you turn your back on someone in Budo you’re dead. You need to keep this in mind when you practice techniques and when you’re an uke. You need to have this feeling when you practice.
When O sensei would demonstrate techniques he would not tell people what technique he was about to do. He would just do it. This would mean they would not be able to adjust to it or spoil it.
If your partner is trying to escape from your techniques then you don't need techniques. Why would you want to throw someone who is trying to get away from you. An uke should set their feet and hands and try not to move. Just like a punching bag in a boxing gym. The bag does not try to get away from the boxer. It just hangs there, definitely. A good uke should be the same. Once we have an unmoving uke we can study how to break their balance and control them with a set technique.
When the partner becomes reactive to what is happening then the Nage must also react to this reaction. This is a different kind of study. This is not traditional Aikido Keiko. It becomes Jiyu waza."