Whenever someone new comes in the Dojo it is usual to have the first part of the class focus on learning about their center. Without knowing your center it can be very difficult to know where to begin with any of the movements or breathing concepts in traditional martial arts. This center point is just a couple inches below the navel or belly button. Called the Dantien in Chinese, Hara in Japanese, and in Yogic Traditions it is known as the sacral chakra. This specific spot on the body is of supreme importance to Karate, Tai Chi Chuan, Jujutsu, Aikido, and every other traditional martial art. So why is this spot of such importance, well first it's best to establish just what all these arts and exercises are designed to achieve.
The basic premise from a purely physical standpoint is to focus on the idea of achieving the maximum potential the human body is capable of. This can be in terms of balance, overall strength and endurance, as well as feats of awareness. The pursuit of achieving the perfection of the possibilities of the body is where Yoga, Tai Chi Chuan, and Karate all begin from. It is also why the Hara/Dantien/sacral chakra is of such importance.
It sounds logical then to say that in order to achieve the highest potentials of the human body a person must develop all the movements and expressions of their body to it's maximum levels. To do that all the movements must be coordinated to work together as one powerful and fluid whole. This is why the martial artist is constantly striving to connect the turning of their ankles with the twisting of their torso and to carry the movement through into the rotation of their forearm, and finally ending with the clenching/snapping/twisting/pushing/punching of their hand. It is an old saying that to have a strong punch you need a strong leg. What connects the legs to the arms is the torso and the Hara is the center of exchange point between the two.
Throughout history there has been numerous warrior castes. The Sparta, Maori, Inca, and Norse peoples all had powerful warriors in a variety of expressions and fighting skills. Yet they all had the same basic body movements to work with. They all had to obey the limitations and dynamics of having two arms and two legs connected by a torso with a head on top. No other way is possible. This knowledge of how to properly transfer kinetic energy through the entire body via the Hara must have been known by all highly trained warriors throughout time to varying degrees. It is simply the product of seeing things as they are. You can see this when a baseball pitcher throws their pitch, or a hockey player shoots a slapshot. They have to use the torquing of their hips in perfect coordination with their arms and legs. And whether they are aware of it or not they also have to coordinate those motions through their hara.
In Karate and other traditional martial arts this observation of the Hara being the center of all powerful physical movements is only one facet of the importance of that spot. The Hara is also considered to be the center of ones qi flow and therefore the center of ones entire being.
In all traditional martial arts the idea of qi, or chi or in Sanskrit prana all refer to a kind of energy that has numerous characteristics and descriptions. The most common theme however is to call it "life force energy" as it tries to identify the very energy of life itself. A person with great qi is healthy and full of vitality while a person who's ki is low is likely ill or at risk of disease. The masters of old recognized the relationship between physical health and ki and so designed their arts to also increase a persons level of ki as it flows throughout the body. This increase of ki flow was found to also dramatically increased the power and abilities of the the person's self defense. Something anyone can come to know personally but only as a result of ones own training and effort.
The increasing of ki as it flows through the body is done by a specific kind of breathing technique. In the total scope of what's available there are dozens of various breathing techniques that all claim to increase vital energy but they all start with, and are based on, deep diaphragm breathing.
If you take your hands and connect the thumbs then align the fingers to cross over each other sort of triangle, then place yours thumbs in your belly button the spot where the fingers cross (it should be a couple inches below the navel) is your Hara. Sit or stand in a comfortable position then breathe into this spot. Focus on keeping a straight spine in whatever position your in and breathe deeply into your belly or Hara. Feel the incoming air expanding that area like a balloon while your exhalation contracts the stomach inwards with mindful and subtle flexing of the abdominal muscles. Breath in through your nose and out through the mouth allowing the tongue to rise to the roof of your mouth on the inhalation and then lower to the floor of your mouth on the exhalation. Do this while releasing all tension in the body and you will begin to cultivate ki. This kind breathing is the starting point for all physical body-mind meditations like Karate or Yoga but also the beginning point for the sitting meditations of Zen and Taoism. All the masters of these arts say to aim at breathing like this all the time.
By breathing like this a person can develop the ability to alter their state of consciousness. Past studies have shown practitioners of Zen and Yoga display an alpha wave activity during periods of meditation. A martial artist develops the alpha wave state in the practice of Kata but all are linked to breathing with the Hara. So we come full circle and see that this center point has many layers of purpose and meaning. It really is a critical concept for anyone seeking to develop themselves physically or spiritually.
By simply being aware of your center you gain a position to grasp the power of your total being and you then will have seen the goal of the martial arts practitioner. To seek for total perfection of their entire being is is an infinite path to follow as perfection cannot be achieved but only sought after. So Like the beautiful mandala art of Buddhism it all begins with the center point and spirals out to infinity suggesting that to develop a relationship with your center allows the universe to follow.