When training focus on the waist movement. As the tailbone relaxes and sinks the waist drops and loosens. The loose waist can twist more easily. The twisting waist causes the energy the limbs and especially to the arms to move as the torso moves. The arms do not move without the waist movement. Feel the waist connected to the mingmen, the kidney, in the back as if there were a force connecting the back to the dantian. The tail bone drops and with it the waist drops and loosens and allows the energy to sink to the feet. A dropped waist is loose and allows twisting to occur and for energy to circulate.