A discussion on the G+ forums back in 2013 May led to the subject of fa jing, or “exploding force.” This is the usual term used by kung fu practitioners to describe manifesting their force in various ways, usually an explosive or powerful strike.
There are many different ways to train fa jing (exploding force, however schools decide to call the term). A lot of Southern Shaolin influenced kung fu sets, for example, will have a special section right at the beginning of the set (called ta chong, or “force training on stance”; it literally translates to “hit stance”) to develop the type of internal force application called for in that certain set. This is relatively less common in Northern Shaolin influenced kung fu sets and styles (e.g. Tantui, Eagle Claw, Taizuquan, and Lohanquan) where there was more of an emphasis on developing internal force and the skill to “explode” that force either through set practice itself or, more commonly, with other special force training sets like the Eighteen Lohan Art (different from the more famous Eighteen Lohan Hands qigong set).
It most certainly takes time to learn how to do this effortlessly in application. At the beginning, students are occupied just making sure their feet, waist, body, and hands are in the right position and getting the form correct, and then they move on to the transitional movements which help propel force from the dan tian to the striking surface (weight transition, waist rotation, etc.) Being able to explode and manifest force in application is one of those skills separating a student from an adept. Being able to manifest force even in seemingly impossible situations is a hallmark of a master.
Naturally (and interestingly), different schools have different opinions on how to properly manifest force. In Shaolin Wahnam, we get the form right, add flowing energy, and explode the force from the dan tian. The school I trained at before, Chinese Taoist Martial Arts Association, the emphasis was getting the form right and then using our physical structure to root and propel ourselves from the ground (the emphasis was on the balls of the feet, as opposed to the abdominal dan tian; in fact, this school does not believe in cultivating internal force or energy for fa-jing through classical methods like stance training; they rely exclusively on physical structure, which has its own advantages and disadvantages).
My first Taijiquan master’s emphasis was on using Reversed Breathing to cultivate energy at the abdominal dan tian and later to “fill” or “charge” the entire body with energy for fighting (he also had some emphasis on waist rotation). Another Taijiquan master that I met and briefly trained with emphasized Silk Reeling exercises to loosen the body in order to effortlessly transmit force into an opponent.
I wasn’t taught any particular breathing method from Shaolin Wahnam other than to ‘breathe naturally.’ I have noticed that I occasionally will unconsciously use Reverse Breathing in my strikes, but I don’t make any particular effort to do so.
My grandmaster once mentioned in one of his trimonthly Q&A’s that, all other things being equal, someone using Abdominal Breathing would have more stamina while someone using Reversed Breathing would have more power. I may experiment with this during my evening practice session.
My current kung fu goals are increasing my internal force for sparring, which for me (at my current developmental level as well as what I’ve been taught by my various masters) is best met by stance training (e.g. Baguazhang stances and Golden Bridge) and force training on stance exercises (e.g. One Finger Shooting Zen and Lifting Water).
I’ve met and trained under two masters who used Reverse Breathing for some time and they both had impressive internal force. As an aside, they both also looked like they had a very firm watermelon for a belly; one of them was able to bounce me away several feet by body-checking me off of his belly!