- Moving and Coordinating; running, jumping, rolling, lifting, stretching, etc.
- Static Structure; The ability to hold a static shape for a long period of time, and transfer force applied on any part of the body to the feet, the back or another limb.
- Continuous Structure with Movement; All muscles must move in twists and spirals following the flow of the bones and ligaments. Muscles weaken and become sensitive. Force can be applied in motion at any angle from any part of the body. Force can be avoided without losing whole body integration.
- Empty and Full at the Same Time; All muscle tension must be discarded along with all intention to move. Any solid concept of body structure must be discarded or melted away. Muscles function like liquid and air. (Power becomes unstoppable but unfocused and difficult to direct.)
- Whole Body Becomes a Ball. Resistance training for big muscles only. Small muscles are used mainly for sensitivity and force transfer (ligament support). Muscles move only by "ten directions breathing," they move in all directions using expansion and condensation, not lengthening and shortening.
The separation of jing and qi, which happens automatically in stillness, needs to be available in motion to enter level 4.
In order to act through a body, that body must be felt as a dream. Dreaming is not like the conscious mind. If you think about running, you are likely to stumble. In order to run, speak, or do any of these types of muscle training, you must first dream it. In order to reach level 5, levels 1 through 4 must be felt as dream. In other words, they can be done spontaneously by feeling, without thinking, or willing.
From my experience, this order is essential. Each level takes a minimum of two years training. Some internal traditions attempt to start their training at level 4 and then go back and fill in gaps in levels 1 and 2 through diligent forms practice. The attempt to fill gaps in level 3 through push-hands training. That seems like a mistake.
The quickest way to get level one skills is through rough play or dance (forms with speed and rhythm).
Level 2 can only be learned through a teacher/partner who tests your structure.
Levels 3 and 4 will be inhibited by strength training.
The key to transitioning from level 3 to level 4 is non-aggression, wuwei. Aggression is refined to perfection and then discarded. This transition probably requires working with emotionally mature partners.
Applications do not work at level 4. Period. But paradoxically, the ability to use weight and momentum improves.
The good news! Yes, it takes at least ten years (two years for each level, and a minimum of three hours everyday), but levels 2 through 5 can be practiced at any age. Levels 2 through 5 actually get easier with age because muscles become weaker and skin becomes looser!