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.
Don't fight too hard. 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 can't possibly lift something up far away from your body. Use your legs, but do not fool around in them 'searching for power'.