Below are some definitions from Chinese sources concerning Internal Strength. Whilst important, Internal Strength is not the sole purpose of Internal martial arts.
1) 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
2) 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
3) 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
4) 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
The same process is mentioned in 'The Principles Of Taijiquan' by Yue Tan (his father Yue Huan Zhi was famous for his Kong Jing in his Taijiquan), 1991, Shanghai Translation & Publishing Centre, Inc, ISBN 7-80514-779-5/G.222
Chen Wei Ming mentions the same process in his Taijiquan Da Wen (Questions & Answeres On Taijiquan) which unfortunately is not completely translated by Ben Lo, I have the original book which has this statement and will fax the relevant section to anybody who wishes to verify it (its in Chinese unfortunately).
Cheng Man Qing mentioned the process in his 13 Chapters (last part of treatise 2). English translation: Cheng Tzu's Thirteen Treatises on T'ai Chi Ch'uan, North Atlantic Books, 1985, ISBN 0-938190-45-8
Chen Xin refers extensively to TCM material that which has as its basis the 3 treasures in his book 'Chen Shi Taijiquan Tu Shuo'.
Chen Zhen Lei also refers to the same medical qi in a disseration on it in the book 'Taijiquan Ming Jia Tan Zhen Di', 1992, China Television Broadcasting Publishing, ISBN 7-5043-2032-3/G.757 I translate this portion: 'The Qi mentioned in Chen style Taijiquan...It does not refer to the oxygen we breath into the chest and the human body's different kinds of strength (li), but refers to the widely known in Chinese Medicine's Correct Qi (Zhen Qi), Original Qi (Yuan Qi), Meridian Qi (Jing Luo Zi Qi), Refined Qi (Zhen Qi), etc kinds of Qi; also includes martial arts and qigong study's Internal Jing (neijing), Internal Work (neigong), etc kinds of Qi.
Hao Yue Ru (Wu Yu Xiang style) mentions it in his 'Wu style Taijiquan Important Points', his first point was 'hand, eye, body, step, Jing, Qi, Shen'. This reference is found in Hao Shao Ru's book 'Wu shi Taijiquan', 1992, Peoples Physical Education Press, ISBN 7-5009-0756-7/G.725
There is a whole chapter on the 3 essences in the book 'Cheng Pai Gao Shi Ba Gua Zhang Pu' edited by Liu Feng Cai, Tianjin Scientific Technology Publishers, 1991, ISBN 7-5308-0997-0/G.234
Jing (Essence) is said to come from the kidneys and if we equate that to the Western adrenal hormones, some of which regulate metabolism as well as blood flow within the body, we get an idea of how this might energise the body for health and further development. Deep abdomenal breathing not only brings in air to the body for good gaseous exchange but also messages the organs in the abdomenal cavity and the kidneys.
Promotion of good circulation in the internal organs (zhang fu) forms a good basis for bodily development. Such bodily development is usually attributed to Qi which is, for the Chinese at least, the lifeforce of the body. It is consists of the jing of the kidney, refined food transported and digested by the spleen and the stomach and clear air taken in by the lungs. In other words it is the vehicle for bringing nutrients and energetic elements (the result of good organ function) to the body, including the bones and musculature. Good circulation means a healthier body and mind. The deep breathing and mental focus to bring physiological changes to improve circulation are a result of the mind which is a part of the conciousness (Shen).
Raised levels of conciousness also means raised levels of perception and awareness which in a combat situation is certainly relevant. Differences in levels of perception is crucial in combat and is a major determining factor in the outcome of any encounter. The efficient structure of the body reduces internal 'noise' in the nervous system and the increased metabolism and efficient functioning of the organs in the body all form a good basis for developing the brain's capabilities. With a more efficient and effective mental process and focus linked intimate with physical control of the body the cycle repeats and forms of basis of even greater development. The Jing, Qi and Shen paradigm is therefore cyclic in nature and the robust body and mind formed by this process is a result of such internal work and strength.
Even removing the terms and concepts that are regarded as esoteric by some, it still forms a good method to build up a foundation through good areobic respiration, good circulation, proper/enhanced organ function to form a basis for mental and physical development.
With a robust body and mind formed, then comes the question of how to efficiently use it, or in the case of Taijiquan, how to efficiently use it in combat.
Paramount is the conciousness (Shen) which forms the intent which leads the body. The generation of physical power via mental intent brings together both the mind and the body in combination with the physiological changes in the musculature caused by mental focus being the foundation. To support efficient transfer of such power, a good efficient structure is needed. For such power to be transmitted out the centre of mass should be isolated and a good root (line of force transmission from the centre of mass to the point of resistance, usually gravity) is required. In combat, here is where method, strategy, technique and positioning come in. Techniques and body usage in a martial art can be based on internal or external generation of the movements. This determines the place internal work has in the martial arts system and its usage.
The training sequence, principles and practices behind it, etc, for Taijiquan can be found on the other pages on this website. Each stage in the training sequence builds up and trains the art in a progressive manner. The form training trains the body and mind's focus and structure as well as the efficient execution of the techniques. It also enables the practitioner to be more aware of his body and what its doing, this eventually helps him understand what the opponent is doing in his body. Push hands is more than just merely training sensitivity, it also teaches how the 13 techniques work technically, how they feel like and how they are countered. The 8 techniques and 5 directions which form the thirteen techniques represent the 8 was which a attacking force and structure is dealt with and turned to one's own advantage and the 5 directions direct the positioning and spatial awareness to be in the right place at the right time to execute it (I believe the Aikido people call it Ma-ai).
In addition to the combative elements delineated in some pages on this website, I think I'll elaborate a little on the mechanism of push hands here. Contact is the means by which sensitivity to the opponent is cultivated, maintaining that contact through continuous sticking, adhering and following is achieved by cultivating zhan nian jing (adhering sticking jing) which is distinct from peng jing (ward off jing) which is an outward and upward type of jing. This kind of jing maintains contact even when the structure is 'disconnected' from the centre of mass to prevent the opponent from detecting it and controlling it via contact (a very possible case when in contact with another Taijiquan exponent). The structure only connected to the centre when using jing in any of the techniques to blend, redirect, take initiative, counter, strike, etc. The centre and root always being kept out of harms way through information gleaned through this sensitivity. This allows the centre to 'suddenly appear and disappear'. It also conforms to the principles of 'not resisting and not losing contact' and the opponent ends up entering into emptiness, finding no purchase for his techniques. This sticking and following without resisting brings forth the characteristic of softness in Taijiquan. There aim is to beat a greater force with a lesser one appropriately applied and to beat a faster one with a slower more effective one and of course not getting hit in the process. All the while keeping good structure and not exposing one's weaknesses to the opponent.
Its not just the opponent's structure, centre, root and strength that can be sensed but also his intent and his 'reading pressure'. This allows one to actually present a false centre, one that can be moved out of focus quickly, or an illusion of a centre by emulating it via structure and so 'entice' him into emptiness. This is a form of trap. Neutralisation need not be linear, one can actually flow around the structure to get behind it and the strength in it to add to it and so take over control of it though control of the centre is paramount since in controlling that you effectively control the whole body.
Efficient power and its flow should be smooth and unimpeded by structure and generation. This brings out the Taijiquan characteristic of 'sung' which can is both 'relaxed' and 'without tension'. It also brings out the fluidity and multidirectional capability of the flow of power in a technique.
In my view this mode of traditional training can bring results in both combat, health, even mental and spiritual (due to elevated awareness/conciousness) development.
All comments are most welcome.