What is long movement or Changjin in Tai Chi (Taijiquan)? People translate Changjin as “long energy”. I think that “energy” is always a bad translation for jin and it’s better to leave all kinds of energies out. At least for this discussion. “Quality” is a much better translation. Changjin means that there must be a “long quality” in the medium and large frame practice of Yang style Taijiquan. Long quality is in the shenfa or body method. In Yang style “just making movements large” is not enough. Long movement must have quality. Long movement is a “stretching quality”.
But the arm does not visually have to be fully stretched. The secret is not in the arms. Instead, the stretching quality starts from the lower back and here, it’s supported from the dantian. The stretching movement goes from the lower back, the whole way up from the lower ribs, spine, through the scapula and it’s carried out through the whole arm, right out to the fingertips. The arm can have a certain firmness but can not be tensed. If the movement of the wrist is coordinated with the movement of the waist, there should be a twisting sensation felt through the whole arm. Connected with the dantian, this is practicing what is called “twisting silk reeling” in Chen style. The movement should be smooth and uninterrupted. The movement is very strong. In movement, an opponent can not fold the practitioners arm or in any way compromise it’s structure.
If all of this you feel uncomfortable and tense, well, you might tense too much. Focus more on the legs and the waist/dantian and try to stabilize your movement from the roots and up. Successful and relaxed long movement in Yang tai chi demands a very strong base and great waist movement. If the stance is lacking or the roots are not fully developed, the practitioner is suggested to focus more on relaxation and comfortable movement instead of the stretching quality.
Take a look at these two Yang masters. If you have practiced for a while and is acquainted with form practice, can easily see that they have a “stretching quality” through out the arms, all of the time and in any movement. You should also be able to see that the strength of the arms comes from the back and legs.