This is yazhang, applied to a partner. The technique is a yazhang, and when applied, the power is anzhang.
This trains the principles of whole body strength settling down and scooping up, the method of training the deep skill of whole body strength, the method of sticking with whole body strength.
1. Players stand in turned mabu or mabu with the same side forward, palm to palm. They take turns doing yazhang on each other, putting enough force to make the partner need to find the right lines of power and direction.
Do not put too much power into your yazhang. If you lock it out your partner cannot lift your arm. Put enough power to make him/her work very hard. Remember that your partner can also lock you down if you go too hard.
Don't fight too hard, use enough power to help your partner find the right line for this specific technique. If you really couldn't lift someone you would change your technique – do a shoulder strike for example. When you lift your partner's arm keep as close to a vertical circle as you can. You cannot possibly lift something up far away from your body. Use your legs, but do not fool around in them 'searching for power'.