In this excerpt from his book Xing Yi Quan Fighting Skills, Master Shang Ji discusses the attacking and defending methods and the life nourishing (Yang Shen) aspects of Drilling Fist.
Application – Attacking and Defending Methods
Zuan Quan is fundamentally an elbow strike. Therefore Li (Force) is in the elbow. The force of the elbow wraps (Guo) and squeezes (Ji)[1] inward toward the 
centerline of the body. The whole body is tightly guarded, looking for a hole in the opponent’s defense. You must bind up (compact or shrink the body) and enter with spiraling, rotating power in order to attack the opponent. The Boxing Classic (Quan Jing) says: First strike, and then defend. The front hand intercepts (Jie), covers (Gai), holds down (Ya) and pats (Fu), the opponent’s forearm or wrist in order to control him. The rear hand follows closely and the fist turns upward and drills outward to his nose or chest. In this way it can be used as an entering step that strikes the opponent to lift and throw him out.
If the opponent is big and heavy and I afraid my strike will not be strong enough, I can first use the foot by turning it outward and treading on his instep, as I drill outward to strike his cheek. I can also not enter and just kick the groin. One can enter in linked stages, step by step; one step and one drill; shaking his foundation and then with one blow gaining victory.
Boxers commonly say: Even a brave hero cannot withstand three Zuan Quan; Zuan above, Beng below; one Zuan, one Beng; the feet go forward in half step or inch steps. This is called the “ring linked concentrated hammer.”[2] It should be pointed out that when using Zuan Quan to enter and strike, no matter the size of the opponent, no matter if one uses half steps or inch steps, the foot must tread (stamp) to the opponent’s center, so that your center strikes inside his center. You cannot enter from the side door. Entering obliquely is useless.
Dispelling Illness and Nourishing Life (Yang Sheng) Method
When practicing Zuan Quan in order to dispel illness and nourish life, do not train it quickly and suddenly like a “flash of lightning,” and do not think of striking with hand and foot whole body power. Instead one should be gentle and yielding, coordinated and harmonious. Make sure that the movements and the respiration are coordinated and unified. The body, waist and spine rotate and turn, expand and contract. Zuan Quan moves and opens, circulating the One Qi. Its Qi emits from the kidney, like water gently curving, turning and evenly flowing. Where are the kidneys? They are the zang organs located in the back, one on the left and one on the right. The upper part is connected to the brain and muscle and the lower part from inside to outside is connected in sequence to the big muscle, the side waist muscle, and the adjoining transverse waist muscle. This preserves and maintains the body’s internal environment, harmonizes the blood and determines sexuality.
Notes:
[1]挤 Ji: squeeze, crowd, push, jostle. To crowd or cram – like shouldering or squeezing one’s way onto a crowded bus or train.
[2]连环攒子锤 Lian Huan Zan Zi Chu
