For all martial arts there is a common set of requirements that need to be addressed when it comes to success in combat. They can be broadly classified into 5 catagories:

1. Power
2. Speed
3. Placement
4. Technique
5. Sensativity

The Internal martial arts place their main emphasis on training the internal factors of a person as a means of preparing the body to be effective in combat. The three internal elements trained are Jing (essence), Qi (vital energy - akin to life force) and Shen (spirit). The body needs to be strengthened and healthy before it can engage in combat. The internal methods train the body for the improved generation of Jing (essence) through keeping the body at the optimum stress level for its healthy functioning which means also the removal or dealing with destructive stress. This returns the body to its natural relaxed state which encourages the proper smooth circulation. This forms the basis for a regulated and healthy endocrine system which leads to the improved generation of Jing.

This in turn leads to the improved output of Qi which is a result of the improved metabolism through the abundance of Jing. Qi is derived from the nutrients we eat and the air that we breath. Qi itself flows with the blood and both can be controlled through mental focus. Proper mental focus leads the qi round the body improving vitality through improved blood flow and sufficient supply of nutrients, gaseous exchange and vital energy. The breath is very important in qi generation and deep breathing efficiently utilising the capacity of the lungs is important but never to the point where it becomes unnatural. This leads to an improved tonus in the musculature and ultimately leads to a healthy body.

The mind leads the qi. The Shen (spirit) which is a manifestation of consciousness is thus trained and is an indispensable part of this cyclic system.

In martial arts, its not how great the power is but how efficiently it is generated and how appropriately it is used that is the key to success. Great power without control, focus and a clear mind having sufficient information to apply it appropriately is quite useless. The frame work for power generation is a good root born of a lowered centre of gravity for stability and the efficient structure for force to flow from it to the ground to form a base of resistance for the power generated to push against. Also important is proper body alignment so that the force is efficiently transmitted through the structure. We should note that these two factors do not constitute internal strength and are present in most martial arts, both internal and external.

Internal strength is a result of training the Jing, Qi and Shen and is a combination of efficient physical power (Jing - not the same as essence, its a different Chinese character) generated through muscular tonus, appropriate application through mental focus and stability, and a healthy body capable of handling the stress of combat which forms a basis for both of the former. Mental focus determines how efficient this is since it is the focus that defines whether the the action is efficient or not. The resultant motion is smooth because it does not have any retained power in the form of tension and rounded because of the nature of motion of the joints and their efficient usage. Because of its mode of generation Internal Strength (Nei Jing) can flow even without apparent outwardly visible motion.

The speed striven for is effective speed. In internal martial arts, the faster technique may not be the victorious one. Efficient motion is essential for speed, as is a structure that is conducive to quick motion (i.e. no double weighting). There are two main points on speed when it comes to combat. The first is to get out of the way of the attack, the second is to counter the attack with the minimum speed requirement. The speed trained in the internal martial arts is the speed of the whole body which is a co-ordinated whole. In Taijiquan, the speed of training is mainly slow, this allows one to train the body to move in an efficient fashion with no tension. It also allows obstructions to the flow of movement due to structure or tension to be detected and removed.

The placement and position of the body and body structure in relation to the opponents is very important in martial arts. It allows one to be in the optimum position to counter or to attack with minimum effort with maximum effect and to be difficult for the opponent to counter. This minimises the danger to the exponent while giving him a good vantage point to initiate his counter or attack.

Proper placement is a result of knowing the opponent(s) centre and structure. It also requires knowledge of effective attacking angles and inherent flaws in body structures in each type of posture. Placement changes in relation to the opponent and so there is more or less constant change in a combat situation.

The technique of the art is how the body is used effectively in combat. A technique is only good if it is applied appropriately. Each martial art has its own set of techniques to deal with the different combat situations. Each conforming to the principles governing and defining each individual martial art style.

In the internal martial arts, the techniques are grounded in efficient structure and motion. The movements are naturally rounded, this turns aside incoming force from reaching and affecting the centre of mass of the body and the body itself to cause damage. The incoming force is either redirected out of its intended focus or turned against itself or to the attacker's disadvantage.

Sensitivity is key to Taijiquan as a martial art. The ability to stick and adhere to the opponent allows the Taijiquan exponent to 'listen' to the opponent's structure and to detect its flaws, to locate and effectively control his centre of mass from which all his body motion ultimately relies on. Sensitivity is trained in the form when it is done slowly. This teaches sensitivity to one's own structure and centre as well as sensitivity to the environment as one does 'push hands' with the air, being so relaxed that it can even react and neutralise air. In push hands, one trains sensitivity with a reactive opponent able to take over the initiative. This is knowledge of self and knowledge of opponent from which victory will come.

Neigong is more properly translated as Internal Work and internal strength refers to nei li or nei jing. The term neigong is defined as follows by the following sources:

• Refers to martial arts' specialised techniques and methods to train the human body's internals to attain the goal of a strong internal and robust external. It is martial arts basic skill but also martial arts highest attainment. In the book 'Taijiquan Methods Truth', it states: "This specifically trains the hollow and solid organs (zhang fu), the nervous system (shen jing), sensitivity/feelings (gan jue), the so referred to Essence (jing), vital energy (qi) and spirit (shen) is called internal work (neigong)'. 'The Encyclopedia of Chinese Martial Arts' (zhong hua wu shu shi yong bai ke), ISBN 7-81003-403-0
• Martial arts, qigong term. Refers to activities that focus on the internal aspects of the human body (intent [yi nian], breath [qi xi], hollow and solid organs [zhang fu], meridians [jing luo], blood flow [xue mai]) in training, in the bid to attain a robust internal (nei zhuang). For example, silent work (ching gong), sinew changing internal robust work (yi jin jing nei zhuang gong), pile standing (zhan zhuang), eight trigram turning revolving work (ba gua zuan xuan gong), etc, are all forms of neigong. 'The Big Dictionary Of Chinese Martial Arts' (zhong guo wu shu da ci dian) ISBN 7-5009-9463-0
• Refers to the specialised system of training of a martial artist to increase Essence (jing), vital energy (qi) and spirit (shen) beyond normal quantities to attain internal robustness. 'Chinese Martial Arts Dictionary' (zhong hua wu shu ci dian), ISBN 7-212-00042-6
• Nei Jing - Martial arts jing method term. Refers to the kind of strength obtained after martial arts training that is able to change direction in accordance to the mind's intent, able to be great or little. Because its movement is within and not external it is called Internal Jing (Neijing). This kind of Jing gathers the whole strength of the body to a single point of power and is called Coordinated/Neat Jing (Zheng Jing). 'The Big Dictionary Of Chinese Martial Arts' (zhong guo wu shu da ci dian) ISBN 7-5009-9463-0

Jing, as referred to in Chinese martial arts, is a coordinated, rooted, efficiently focused strength. A clear definition of this kind of strength is found in Li I Yu's Five Word Formula. At this point, Jing still has not been defined into Internal or External types. This definition of Jing applies both to Internal and External types of martial arts.

1. Rooting: For strength to be properly generated, it needs to have a base to provide the resistance to form a base for it to push against. The emphasis on pile standing in many martial arts is to build up this base by lowering the centre of gravity of the body to enhance stability and the efficient transfer of force from the centre of gravity to the ground. This means that the centre of gravity should first be identified by the practitioner and isolated so that it can be distinguished clearly. The stress is on strong support with the minimum of effort utilising the efficient structure. Lowering the qi to the Dan Tien which roughly corresponds to the body's centre of mass helps achieve this.
2. Coordination: The different joints and muscles in the body must be coordinated to work together to produced a strength born of the whole body working efficiently together. When antagonistic groups of muscles do not work in a coordinated fashion, tension is created which lessens the resultant force. The coordination is also with breathing which affects the state of the body. Coordination using the centre of mass as a base which is supported by efficient structure allows an efficient path for strength to flow. Hence the importance of the Dan Tien not only as a origin point of the root and the exertion of strength but also as a region where qi is stored and emitted from.
3. Alignment: The proper alignment of the bones in the body provides the structure by which the force is transmitted and provides a clear path for strength to flow from the point of focus to the ground. With the bones efficiently bearing the stress of the reaction force, the musculature can work efficiently without unnecessary exertion.
4. Focus: The above three characteristics are dependent on the focus of the strength which determines its efficiency. Focus denotes a point where all the body's potential is directed at and also to the task to be accomplished by the resultant force.

With the above four factors in place, one is capable of generating Jing which means that one can properly Fa-Jing or emit Jing. Fa-Jing is present in both internal and external martial arts and simply denotes an emission of strength. It should be noted that in Taiiquan, the aim is not great strength but beating a great force with a smaller one. The ability to Fa-Jing does not denote ability in Taijiquan or other martial arts since no art is based on Fa-Jing alone. Knowing when and where to appropriately Fa-Jing is far more important. Fa-Jing inappropriately can be disastrous.

External Jing is where the Jing is derived from the three external elements of musculature (jin), bones (gu) and skin (pi). This kind of jing is delivered through the exertion of the muscles, hardness of the bones and the toughness of the skin. It relies on hard physical impact and physical exertion to bring its effects to bear.

Internal Jing is where Jing is derived from the three internal elements of essence (jing), vital energy (qi), and spirit (shen). This kind of jing is effected through the strengthening of the essence to provide the generation of qi which nourishes both the musculature, bones, organs and the mind which is the seat of the spirit.

The body's essence (jing) is built up to ensure a plenteous supply, this is transformed into qi which nourishes and provides the vitality to the musculature, bones, organs and also the mind. Qi in traditional Chinese medicinal theory is the basis of life in the body and its presence and relative volume determines the health and vitality of the body. Qi itself is directed by the Mind/Spirit which is itself dependent on qi for its mental capability. The Spirit is an expression of the thought, knowledge, feelings and intent (mental focus) of the mind. A strong spirit makes for clear thought, enhanced perception, better intent (Yi) which are assets to all situations, including martial ones. Intent brings about the physiological changes which opens the blood and qi flow along the path and at the point of focus. Hence the theory the mind leads and the blood and qi follows.

With increase circulation and qi flow, the musculature assumes a better tone, which results in the 'filled' feeling that is experienced by those who do some form of internal work (nei gong). It is this increased tonus and tenacity that serves as the origin of Internal Jing. It gives Internal Jing its 'propelled' and 'hydraulic' characteristics. This increase qi flow is directed by the mind which results in the creation of Internal Jing. The musculature remains relaxed with no undue tension.

Internal Jing transfers the strength smoothly into the opponent, not relying on hard impact to damage. This transfer of energy/force into the opponent's body and structure can cause injuries that are not obvious externally.

Visible Jing is also called Ming Jing. It denotes Jing (internal or external) that is obviously visible when it is utilised. The motion of the limbs and the point of focus is exhibited physically. One can also discern if the jing is hard (ying jing or gang jing) or soft (rou jing).

Hidden Jing: the opposite of Visible Jing is Hidden Jing which is also called An Jing. Whereas Visible Jing is easily observed, Hidden Jing is hard to discern. It is based on the internal flow of strength within the body rather than the external manifestation. Like the flow of air inside a beach ball, it is certainly present but it is not obvious when observing it externally yet it provides a reaction upon contact. Contact with someone using Hidden Jing often shows that his external movements may not correspond to his internal flow of strength and its focus.

Hard Jing: manifested rigidly to the point of focus. Its path is fixed and exhibits hardness and stiff resistance.

Soft Jing: has a pliable path which shifts to to accommodate changes in the structure which is in contact without losing the point of focus.

In all internal practices, correct breathing is of utmost importance. Deep breathing also massages the internal organs, ensuring that there is smooth flow of blood and lymph through them, this aids in the creation of essence (Jing). Breath itself is intricately tied to the exertion of strength. The body exhales when exerting strength.

Moving exercises, have the same principles as standing except that instead of still standing, the body is in motion but without losing any of the requirements of the standing. Taijiquan's boxing set is an example of such moving internal strength exercises. These can be trained on their own but full benefit is derived from first attaining the necessary attributes from still standing and then transferring them into moving exercises as it is much easier to cultivate them in standing.