Any form of formerly known strength conditioning is encouraged so long as it does not result in restriction of body flexibility. Many butoh practices automatically will provide strength such as any form of crawling. The following are recommended exercises.
Exercise 1: Tree Hugging
Bear hug a tree with all your might and then pull up with your entire body as if you are trying to uproot the tree. Hold the position until you no longer can (muscular failure). A variation involves also hugging the tree with your legs.
Exercise 2: Tree Climbing
Much whole body strength building can be accomplished by climbing trees.
Exercise 3: Butoh push-up
Engage in push-ups, except, change the various positions of the arms and also the speed and direction of the push-up. Feel body scribbles when going down.
Exercise 4: Jumping Centipede
Get into a low push-up position. If this position is too difficult already, do it from the knees. Suddenly jump forward with your entire body catching yourself and pliéing (softening the landing) with your elbows and shoulders. Feel circular rotations forward (Up, over, down, back, etc.). The momentum will help you. Use the palms for landing until you are ready to increase the difficulty, then use fingers, then subtract fingers, etc.
Exercise 5: Locomoting Bridge
Once enough strength is cultivated to keep a bridge (a backbend on all fours), you can locomote. Increase difficulty by walking in the X pattern (see section Walk) and changing density such as into Ash Walk.