Grandmaster Chen Qingzhou is the key person to revive the ancient training method of Taiji Ball to achieve “dantian bounce” (丹田自弹, dantian zitan), the ability to store and release power at the dantian area. This is a high-level martial skill where the internal energy and the external energy become one. Through years of diligent training, a practitioner’s dantian becomes the center of (automatic) sensing and reacting to incoming energy. The internal dantian rotation not only leads external movements in the arms and legs, etc., but can also generate enough local energy to bounce off a 20g rock 10 centimeters high when lying on one’s back.
In the following video, GM Chen Qingzhou, at age 76, demonstrates “dantian bounce” with rocks of increasing size and weight.
 According to GM Chen Qingzhou (《陈氏太极拳功夫荟萃》，中华书局，2002), this level can be achieved after practicing Taiji Ball 10 times a day for about a year. Readers can adjust their own estimation since we all know there is no one formula that fits all.